Research Interests: Theories and experiments on nonlinear optics/photonics and optical physics of liquid crystalline materials in achiral or chiral phases. Studies of nonlinear optical self-actions and coherent optical wave mixing, beam/image/signal processing, optical switching and modulation, optical limiting and sensor protection applications enabled by unique properties of these novel optical materials. I am also interested in incorporation of such highly nonlinear optical liquid crystals in nanostructures (plasmonic, metamaterials/metasurfaces, waveguides/inverse opals photonic crystals), or embedding nanoparticles in these LCs, to fashion tunable/reconfigurable photonic devices for applications in the spectral region spanning the visible, near IR and IR.

Summary of Technical Publications/Patent
*Author/co-author/editor of 8 books and 15 book chapters.
* Editor of 28 Proceeding volumes [Liquid Crystal Conference I –XXVIII]
* Founder & Editor-in-Chief of 28 Volumes-year of Journal of Nonlinear Optical Physics and Materials [JNOPM 1991-2019].
* H-Index: 60; # of citations: ~15275 [Goggle Scholar].
* Authored and co-authored ~ 737 Technical Publications/Conference Presentations
[296 Refereed Journals and Proceedings; 441 Conference Presentations (including ~236 invited and 36
Keynote/Plenary)
* Awarded three U.S. patents:
– US Patent # 5,552,915 “Liquid Crystal Nonlinear Photorefractive Electro-Optical Storage Device Having
a Liquid Crystal Film including Dopant species of C60 and C70” [9/3/1996]. Sole inventor.
– US Patent #5,589,101“Liquid Crystal Fiber Array for Optical Limiting of Laser Pulses and for
Eye/Sensor Protection” [12/31/1996]. Sole inventor. Invention featured in Innovation to Watch section
of Business Week [May 5, ‘97 Issue], Discovery magazine [3/2000] and Photonic Spectra [6/2000], MIT
Technology Review [4/2000] and several National Newspapers [New York Times, Philadelphia Inquirer,
Houston Chronicles]
– US Patent # 9,140,914 “Apparatus and Method for Stabilizing the Temperature of a Photonic Circuit”
[9/22/2015]. List of co-inventors: Joanna Ptasinski, Lin Pang, Iam Choon Khoo, Yeshaiahu Fainman,
Sungwoon Kim.

Books
1. Author – Liquid Crystals. 3rd Edition (Wiley, NY 1/2022).
A 400-page reference/text book intended for optical engineers, research scientists and graduate students interested in the optical physics, electro-optics and nonlinear optics and photonics of liquid crystals. https://www.wiley.com/en-us/Liquid+Crystals%2C+3rd+Edition-p-9781119705826
2. Author – Liquid Crystals: Physical Properties and Nonlinear Optical Phenomena (Wiley, NY, 1995).
A 300-page reference/text book intended for graduate students, optical engineers and research scientists interested in liquid crystal nonlinear optics and basic physics.
3. Co-author – Optics and Nonlinear Optics of Liquid Crystals (World Scientific Publ. Inc., NJ, 1993).
A 500-page reference book that provides a comprehensive treatment of the fundamentals of optical, electro-optical and nonlinear-optical properties of liquid crystals, devices and nonlinear optics.
4. Co-editor – Nonlinear Optics and Optical Physics (World Scientific, Singapore, 1993).
A 400-page reference book, with 16 authors, intended for advanced research scientists.
5. Co-editor – Physics of Liquid Crystalline Materials (Gordon & Breach, NY, 1991).
A 600-page reference book, with 26 authors, intended for advanced researchers.
6. Co-author – Principles of Optical Engineering (Wiley, NY, 1990).
A 260 –page junior/senior year Electrical Engineering textbook.
7. Co-editor – Novel Optical Materials and Applications (Wiley, NY, 1996).
A 320-page reference book for research level optical scientist/engineers.
8. Co-editor – Novel Optical Materials (World Scientific, 2023).

Book Chapters
1. “Nonlinear Optics of Liquid Crystals,” Progress in Optics, Vol. XXVI, ed. E. Wolf (North Holland,       Amsterdam, 1988).
2. “Nonlinear optical processes and applications in the infrared with nematic liquid crystals,” in      Nonlinear Optical and Electroactive Polymers, ed. P. N. Prasad and D. R. Ulrich (Plenum, NY,        1987).
3. “New theoretical and experimental results on multi-wave mixing and phase conjugation in          liquid crystals and semiconductors” in Nonlinear Optics of Organics and Semiconductors, ed.      T. Kobayashi (Springer Verlag, Heidelberg, 1988).
4. “An overview of Nonlinear Optics of Liquid Crystals,” in Solid State Materials eds. S.           Radhakrishna and A. Daud (Narosa Publishing House, New Delhi, 1991).
5. “Non-resonant Optical Nonlinearities of Liquid Crystals,” in Nonlinear Optics and Optical Physics, eds. I. C. Khoo, J. F. Lam and F. Simoni (World Scientific, NJ, 1993).
6. “Liquid Crystals Nonlinear Optics vs. Photorefractives,” in SPIE Critical Review Series, ed. Pochi  Yeh and Claire Gu (Bellingham, WA, 1994).
7. “Liquid Crystal Nonlinear Optics,” in Frontiers of Polymers and Advanced Materials, ed. P. N. Prasad (Plenum, NY, 1994).
8. “C60-Doped Isotropic Liquid Crystal Cored Fiber Structures For All-Optical Switching and Limiting
Application” in Novel Optical Materials and Applications, ed. I. C. Khoo, F. Simoni and C.Umeton (Wiley Inter Science, NY 1996).
9. “Liquid Crystal Photorefractivity for Recording Holographic Gratings” in Proceedings of 4th International conference on Frontiers of Polymers and Advanced Materials. ed. P. N. Prasad and Z. Kafafi. (Plenum, NY 1998)
10. “Nonlinear Optical Properties of Nematic Liquid Crystals”, in Physical Properties of Liquid Crystals Ed. D. A. Dunmur, A. Fukuda and G. R. Luckhurst (INSPEC, IEE, London, UK, 1999)
11. “Liquid Crystals Photorefractivity” in “Photorefractive Materials, Devices and Applications” ed. F. T. S. Yu and S. Yin [Wiley Inter Science, NY 1999]
12. “Nonlinear Optics – materials: Liquid crystals for NLO” in Encyclopaedia of Modern Optics, ed. Bob. D. Guenther et al [Academic Press, 2004].
13. A. Diaz and I. C. Khoo, “Liquid crystalline nano-structured optical metamaterials,” in Comprehensive Nanoscience and Technology, Vol. 3, pages 225-261 eds. David Andrews, Gregory Scholes and Gary Wiederrecht [Elseier, 2011]
14. N.V. Tabiryan and I. C. Khoo, “Recent Advances in Nematic Liquid Crystal Nonlinear Optics,” Chapter 16, Vol. 7 in Handbook of Liquid Crystals: 7 Volume Set, 2nd Edition edited by J. W. Goodby, P. J. Collings, T. Kato, C. Tschierske, H. Gleeson, and P. Raynes. Wiley-VCH Verlag GmbH & Co. (2013).
15. T.-H. Lin and I. C. Khoo, “Liquid crystals for displays, smart windows, tunable metamaterials, plasmonic nanostructures, micro-ring resonator and ultrafast laser manipulations,” in Novel Optical Materials, ed. I. C. Khoo, F. Simoni and C. Umeton [World Scientific Publishing, 2023].

Journals and Proceedings
1. Editor-in-Chief – J. Nonlinear Optical Physics and Materials, Vol. 1- Vol. 28 [1992 – 2019]
2. Editor – Liquid Crystals I -XXVII [1997- 2023] – 27 Proceedings Volumes of Liquid Crystals Conference in the Annual SPIE Optics and Photonics Symposium.

Research areas and publications- summary and exemplary publications
I. Fundamental studies of optical, electro-optical and nonlinear optical properties of liquid crystals
Discovering and uncovering mechanisms for optically [without or with bias ac/dc field] induced index and birefringence changes and modulations in liquid crystals and developing original theories for underlying material/optical physics. Fundamental mechanisms include field induced liquid crystalline reorientations, photorefractivity and beam coupling effects, short-pulsed laser induced thermal/density/order-parameter modulations, transverse nonlinear phase shift and bistability, stimulated orientation scattering leading to self-starting optical phase conjugation, dynamics of interface switching, two- and multi-photon absorption and molecular energy level population dynamical evolution leading to self-regulated transmission.
These mechanisms can be activated by optical fields from light sources of a very wide temporal range and spectral region spanning visible to infrared. The intensity dependent index changing coefficients characterizing these nonlinear optical responses of liquid crystals in the nematic phase used in conventional display screens [TV, computer, cell phone], as well as in the photonic crystalline phase used in advance optical systems, are in the range of 10-10 to over 10 cm2/Watt – several orders of magnitude larger than most known materials. The response times range from conventional display screen speed of milliseconds for birefringent crystalline reorientation, through micro- to nano-seconds typical of laser induced order parameter modification, to ultrafast [picosecond-femtoseconds] time scale arising from optical field induced electronic wave function modifications.

II. Studies of self-action, wave mixing, transmission switching, nonlinear coupling and propagation, pulse compression and tunable (plasmonic, metamaterials) nanostructure with CW – femtosecond pulsed lasers
Conducting feasibility demonstrations of wide-ranging nonlinear optical processes and operations such as dynamic and storage holography, aberration-free and visible/infrared imaging/wavelength conversion, polarization- and intensity- switching, and self-action devices for modulating and controlling light.
Extremely photorefractive properties of LC enable storage and dynamic holography and aberration-free image recording and processing at very low operation power threshold with a wide spectrum of light spanning the visible to infrared. Ultrafast electronic optical nonlinearities of LC in the form of a single optical element have been successfully utilized in picoseconds- and femtoseconds- pulsed laser modulation (compression, stretching recompression, polarization rotation of complex laser vector fields) LC-cored fiber arrays have also been demonstrated to allow vision/viewing/detection, while protecting eye/sensor against harmful/unwanted intense lights [sun glares, lasers …etc.] by passive optical limiting and control with two- and multi-photon absorptions and order parameters changing mechanisms in liquid crystals. In collaboration with colleagues around the world, we have also demonstrated optical spatial soliton, tunable metamaterials and plasmonic nanostructures and waveguides/ring-resonators.

Exemplary Refereed Journals and Proceedings [from a total of ~293]
Review journal articles
1. I. C. Khoo and Y. R. Shen, “Liquid crystals–nonlinear optical properties and processes,” Optical Engineering 24, 579-585 (1985).
2. I. C. Khoo, “Nonlinear optics of nematic liquid crystals,” Progress in Optics, Vol. XXVI ed. E. Wolf, North Holland (1988).
3. I. C. Khoo, “Extreme nonlinear optics of nematic liquid crystals,” J. Opt. Soc. Am. B28, pp. A45-A55 (2011). Invited paper in Focus Issue dedicated to 50th Anniversary of Nonlinear Optics.
4. I. C. Khoo, “Nonlinear Optics, Active Plasmonic and Tunable Metamaterials with Liquid Crystals,” Progress in Quantum Electronics, Volume 38, Issue 2, Pages 77–117 (2014)
5. I. C. Khoo, “Nonlinear Optics of Liquid Crystalline Materials,” Physics Report 471, pp. 221-267 [2009].
6. D. N. Christodoulides, I. C. Khoo, G. J. Salamo, G. I. Stegeman, and E. W. Van Stryland, “Nonlinear refraction and absorption: mechanisms and magnitudes,” Adv. Opt. Photon. 2, 60-200 (2010)
7. I. C. Khoo (2018) Cholesteric and blue-phase liquid photonic crystals for nonlinear optics and ultrafast laser pulse modulations, Liquid Crystals Reviews, 2018. DOI: 10.1080/21680396.2018.1509387

Exemplary Journal articles by areas
A. Mechanisms for optical nonlinearities and field induced index and birefringence changes in liquid crystals; fabrication of extraordinarily thick/massive liquid crystalline chiral photonic crystals.
1. I. C. Khoo, “Optically induced molecular reorientation and third order nonlinear optical processes in nematic liquid crystal,” Phys. Rev., A23, 2077 (1981).
2. I. C. Khoo, “Theory of optically induced molecular reorientations and quantitative experiments on wave mixing and the self-focusing of light,” Phys. Rev., A25, 1637 (1982).
3. I. C. Khoo, “Nonlinear light scattering by laser and dc field induced molecular reorientations in nematic liquid crystal film,” Phys. Rev., A25, 1040-1048 (1982).
4. I. C. Khoo, “Re-examination of the theory and experimental results of optically induced molecular reorientation and nonlinear diffractions in nematic liquid crystals: spatial frequency and temperature dependence,” Phys. Rev. A27, p.2747-2750 (1983).
5. I. C. Khoo and R. Normandin, “Nanosecond laser-induced transient and erasable permanent grating diffractions and ultrasonic waves in a smectic film,” J. Appl. Phys., 55, pp.1416-1418, (1984).
6. I. C. Khoo and R. Normandin, “Nanosecond degenerate optical wave mixing and ultrasonic wave generation in the nematic phase of liquid crystals,” Opt. Letts., 9, pp. 285-287 (1984).
Nonlinear guided Waves
7. I. C. Khoo and R. Normandin, “The mechanism and dynamics of transient thermal grating diffraction in nematic liquid crystal films,” IEEE J. Quant. Electronics, QE-21, Pages: 329-335 (1985).
8. I. C. Khoo, T. H. Liu and R. Normandin, Nonlocal transverse dependence of molecular reorientation induced in a nematic liquid crystal by a Gaussian laser beam. Mol. Cryst. Liq. Cryst. 131, p. 315 (1985).
9. I. C. Khoo, P. Y. Yan and T. H. Liu, “Nonlocal transverse dependence of optically induced director axis reorientation of a nematic liquid crystal film–theory and experiment,” J. Opt. Soc. Am., B, Vol. 4, Pages: 115-120 (1987).
10. I. C. Khoo, J. Y. Hou, T. H. Liu, P. Y. Yan, R. R. Michael and G. M. Finn, “Transverse self-phase modulation and bistability in the transmission of a laser beam through a nonlinear thin film,” J. Opt. Soc. Am., B4, pages:886-891 (1987).
11. I.C. Khoo, S. Slussarenko, B. D. Guenther and W. V. Wood, “Optically Induced Space Charge Fields, DC Voltage, and Extraordinarily Large Nonlinearity in Dye-doped Nematic Liquid Crystals,” Opt. Letts 23, pp 253 – 255 (1998).
12. I. C. Khoo, P. H. Chen, M. Y. Shih, A. Shishido, S. Slussarenko, “Supra Optical Nonlinearities of Methyl-Red and Azobenzene Liquid Crystal –doped Nematic Liquid Crystals,” Mol. Cryst. Liq. Cryst. 358, 1-13 [2001]
13. I. C. Khoo, M. Y. Shih, A. Shishido, P.H. Chen and M. V. Wood, “Liquid Crystal Photorefractivity – Towards Supra-Optical Nonlinearity,” Opt. Mate. 18, 85-90 (2001).
13. I. C. Khoo, C. W. Chen, K. L. Hong, and T. H. Lin, and S. Zhao “Nonlinear Optics of Nematic and Blue Phase Liquid Crystals,” Molecular Crystals Liquid Crystals, 594:1, 31-41, [2014]
15. I. C. Khoo, “Dc-field assisted grating formation and nonlinear diffraction in Methyl-red dye-doped blue-phase liquid crystals,” Opt. Lett. 40, pp. 60-63 (2015)
16. Chun-Wei Chen, Tsung-Hsien Lin and I. C. Khoo, “Dynamical studies of the mechanisms for optical nonlinearities of methyl-red dye doped blue phase liquid crystals,” Optics Express 23 pages 21650-21656 (2015)
17. I. C. Khoo, Shuo Zhao, Tsung-Jui Ho and Chun-Wei Chen, “Maxwell Stress induced flow- deformation and optical nonlinearities in liquid crystals,” Progress in Electromagnetic Research [Invited paper for commemorative issue on 150 years of Maxwell Equations] Vol. 154, 51-63, 2015.
18. I. C. Khoo, Chun-Wei Chen, and Tsung-Jui Ho, “Observation of photorefractive effects in Blue-phase liquid crystal containing Fullerene-C60,” Opt. Letts. Volume: 41 Issue: 1 Pages: 123-126 (2016).
19. Chun-Wei Chen, et al, Timothy J. Bunning, Iam-Choon Khoo and Tsung-Hsien Lin “Large three-dimensional photonic crystals based on monocrystalline liquid crystal blue phases”. Nature Communications 8, Article number: 727 (2017) doi:10.1038/s41467-017-00822-y
20. Chun-Wei Chen, et al, Timothy J. Bunning, Iam-Choon Khoo and Tsung-Hsien Lin “Large three-dimensional photonic crystals based on monocrystalline liquid crystal blue phases”. Nature Communications 8, Article number: 727 (2017) doi:10.1038/s41467-017-00822-y
21. Chun-Wei Chen and I. C. Khoo, “Extraordinary polarization rotation of vector beams with ultrahigh-period-number chiral photonic crystals,” Optics Letters 44, pp. 5306-5309 (2019).
21. Duan-Yi Guo, Chun-Wei Chen, et al, Timothy J. Bunning, Iam Choon Khoo*(contact author) and Tsung-Hsien Lin, “Reconfiguration of three-dimensional liquid-crystalline photonic crystals by electrostriction,” Nature Materials. 19, pages 94–101 (2020). DOI:10.1038/s41563-019-0512-3 [https://www.nature.com/articles/s41563-019-0512-3]
22. Chun-Wei Chen and I. C. Khoo, “Optical vector field rotation and switching with near-unity transmission by fully developed chiral photonic crystals,” Proceedings of the National Academy of Sciences (PNAS) 2021, 118 (16). https://www.pnas.org/content/118/16/e2021304118
23. Chun-Wei Chen, Ting-Mao Feng, Chih-Wei Wu, Tsung-Hsien Lin, and Iam Choon Khoo*(contact author), “Massive, Soft, and Tunable Chiral Photonic Crystals for Optical Polarization Manipulation and Pulse Modulation,” Applied Physics Reviews 10, 011413 (2023); https://doi.org/10.1063/5.0139168
24. Lin, TH., Guo, DY., Chen, CW. et al. Directed crystalline symmetry transformation of blue-phase liquid crystals by reverse electrostriction. Nat Commun 15, 7038 (2024). https://doi.org/10.1038/s41467-024-51408-4

B. Optical switching and bistability, self-phase modulations, wave mixing, stimulated orientation/thermal scatterings and self-starting optical phase conjugations; nonlinear guided waves
1. Optical bistability in nematic film using self-focusing of light. I. C. Khoo, Appl. Phys. Letts., 41, 909 (1982).
2. Optical bistability in a nematic liquid crystal film inside a Fabry Perot cavity. I. C. Khoo, R. Normandin and V.C.Y. So, J. Appl. Phys., 53, 7599 (1982).
3. I. C. Khoo, J. Y. Hou, R. Normandin and V.C.Y. So, “Theory and experiment on optical bistability in a Fabry-Perot interferometer with an intracavity nematic liquid-crystal film,” Phys. Rev., A27, 3251 (1983).
4. I. C. Khoo, P. Y. Yan, T. H. Liu, S. Shepard and J. Y. Hou, ‘Theory and experiment on optical transverse intensity bistability in the transmission through nonlinear thin (nematic liquid crystal) film,” Phys. Rev., A29, Pages: 2756-2764 (1984).
5. Observation of intensity-dependent guided waves, H. Vach, C. T. Seaton, G. I. Stegeman and I. C. Khoo, Opt. Letts., 9, 238 (1984).
6. Infrared to visible image conversion capability of nematic liquid crystal film. I. C. Khoo and R. Normandin, Appl. Phys. Letts. 47, 350 (1985).
7. Nonlinear optical properties of liquid crystal films for optical imaging processes. I. C. Khoo, Optical Engineering, 25, 198 (1986).
8. Wave front conjugation with gain and self-oscillation with a nematic liquid crystal film. I. C. Khoo, Appl. Phys. Letts., 47, 908 (1985).
9. I. C. Khoo, “Dynamic gratings and the associated self-diffractions and wave front conjugation processes in nematic liquid crystals,” IEEE J. Quant. Electronics, QE22, Pages: 1268-1275 (1986).
10. I. C. Khoo, G. Finn, R. R. Michael and T. H. Liu, “Passive optical self-limiter using laser induced axially symmetric and asymmetric transverse self-phase modulations in a liquid crystal film,” Optics Letters, 11, Pages: 227-229 (1986).
11. Probe beam amplification via degenerate optical wave mixing in a Kerr medium. T. H. Liu and I. C. Khoo, IEEE J. Quant. Elect., JQE 23, 2020 (1987).
12. Nanosecond laser amplification via degenerate multiwave mixing in silicon. I. C. Khoo and R. Normandin, Appl. Phys. Letts, 5, 525 (1988).
13. I. C. Khoo, P. Y. Yan, G. M. Finn, T. H. Liu and R. R. Michael, “Low power (10.6µm) laser beam amplification via thermal grating mediated degenerate four wave mixings in a nematic liquid crystal film,” J. Opt. Soc. Am., B5, Pages: 202-206 (1988).
14. Stationary and moving thermal grating mediated infrared laser wave mixing and amplification in nematic liquid crystal films. P. Y. Yan and I. C. Khoo, IEEE J. Quant. Elect., JQE25, 520 (1989).
15. Dynamics of total-internal-reflection to transmission switching in a dielectric-cladded nonlinear film. I. C. Khoo and Ping Zhou, J. Opt. Soc. Am., B6, 884 (1989).
16. I. C. Khoo and T. H. Liu, “Theory and experiments on multiwave mixing mediated probe beam amplification,” Phys. Rev., A39, Pages: 4036-4044 (1989).
17. Optical switching by a dielectric cladded nematic film. I. C. Khoo, et al., IEEE J. Quant. Elect., JQE25, 1755 (1989).
18. Nonlinear liquid crystal fiber-fiber coupler for switching and gating operation. I. C. Khoo and R. Normandin, J. Appl. Phys., 65, 2566 (1989).
19. Probe beam amplification and phase conjugation self-oscillation threshold in a thin Kerr medium. I. C. Khoo and Y. Zhao, IEEE J. Quant. Elect., JQE25, 368 (1989).
20. Transient multiwave mixing in a nonlinear medium. I. C. Khoo and P. Zhou, Phys. Rev., A41, 1544 (1990).
21. The infrared optical nonlinearities of nematic liquid crystals and novel two-wave mixing processes. I. C. Khoo, J. Mod. Optics, Vol. 37, 1801 (1990).
22. Stationary equal frequency two-wave mixing with gain in a bipolar birefringent nonlinear medium. I. C. Khoo and N. V. Tabiryan, Phys. Rev. A 41, 5528 (May 1990).
23. Optical amplification and polarization switching in a birefringent nonlinear optical medium: An analysis. I. C. Khoo, Phys. Rev. Lett. 64, 2273 (1990).
24. Theory and experiments on stationary and nearly degenerate optical wave mixing and ring-laser oscillation in a Kerr-like medium: Stationary regime. I. C. Khoo and Wei Wang, J. Opt. Soc. of Am., B8, 1433 (1991).
25. Effects of diffractions and self-phase modulations on phase conjugation self-oscillation in Kerr media. I. C. Khoo and W. Wang, J. Quantum Electronics, JQE27, 1310 (1991).
25. Multiwave mixing mediated optical bandpass filter with thin Kerr medium. Wei Wang and I. C. Khoo, J. Opt. Soc. Am. B, pp. 2088-2093 (1992).
27. Dynamics of transient probe beam amplification via coherent multiwave mixing in a local nonlinear medium-nematic liquid crystal. I. C. Khoo, Hong Li, and Yu Liang, IEEE J. Quant. Electronics, 29, 12 (1993).
28. Self-starting phase conjugation with cross-polarization stimulated orientational scattering in liquid crystal. I.C. Khoo and Yu Liang, Optics Letters, 20, 130 (1995).
29. Holographic grating formation in dye- and fullerene C60-doped nematic liquid crystal film. I. C. Khoo, Optics Letters, 20, 2137 (1995).
30. All Optical switching of infrared optical radiation using isotropic liquid crystals. P. G. LoPresti, P. Zhou, R. G. Lindquist and I. C. Khoo, IEEE J. Quantum Electronics, JQE 31, pp. 723 (1995).
31. M. Peccianti, A. De Rossi and G. Assanto, A. De Luca and C. P. Umeton and I. C. Khoo, “Electrically assisted self-confinement and waveguiding in planar nematic liquid crystal cells,” Appl. Phys. Letts. 77, pp 7-9 (2000)
32. Malgosia Kaczmarek, Min-Yi Shih, Roger S. Cidney and I. C. Khoo, “Electrically tunable, optically induced dynamic and permanent gratings in dye-doped liquid crystals”, IEEE J. Quantum Electronics 38, pp 451-457 (2002)
33. Malgosia Kaczmarek, Andrey Dyaduysha, Sergei Slussarenko and I.C. Khoo, “The role of surface charge field in two-beam coupling in liquid crystal cells with photoconducting polymer layers,” J. Appl. Phys. 96, pp. 2616-2623 [2004].
34. I. C. Khoo and T. H. Lin, “Nonlinear optical grating diffraction in dye-doped blue-phase liquid crystals,” Opt. Lett. 37, 3225-3227 (2012)
35. Chun-Wei Chen, Hung-Chang Jau, Chun-Ta Wang, Chun-Hong Lee, I. C. Khoo and Tsung-Hsien Lin, “Random lasing in blue phase liquid crystals,” Optics Express, Vol. 20, No. 21, pp. 23978–23984 (2012)
36. Iam Choon Khoo, Kuan Lung Hong, Shuo Zhao, Ding Ma, and Tsung-Hsien Lin “Blue-phase liquid crystal cored optical fiber array with photonic bandgaps and nonlinear transmission properties,” Optics Express Vol. 21 Issue 4, pp.4319-4327 (2013)
37. C. W. Chen, H. C. Jau, C. H. Lee, C. C. Li, C. T. Hou, C. W. Wu, T. H. Lin and I. C. Khoo, “Temperature dependence of refractive index in blue phase liquid crystals,” Optical Materials Express 3 Issue: 5 Pages: 527-532 [2013]
38. Ho TJ, Chen CW, Khoo IC. Polarisation-free and high-resolution holographic grating recording and optical phase conjugation with azo-dye doped blue-phase liquid crystals. Liq Cryst. 2018. doi.1080/02678292.2018.1491068.
39. Iam Choon Khoo, Chun-Wei Chen & Tsung-Jui Ho, “High efficiency holographic Bragg grating with optically prolonged memory,” Sci. Rep. 6, 36148; doi: 10.1038/srep36148 (2016).
40. Haiyu Chen, Haowen Liang, Wei-Hung Lai, Cheng-Chang Li, Jiahui Wang, Jianying Zhou, Tsung-Hsien Lin, Iam Choon Khoo, and Juntao Li, “A 2D/3D Switchable Directional-Backlight Autostereoscopic Display Using Polymer Dispersed Liquid Crystal Films,” J. Display Technology, VOL. 12, NO. 12, pp: 1738-1744 (2016)
41. Chen, CW, Brigeman, AN, Ho, TJ, Khoo, IC, “Normally transparent smart window based on electrically induced instability in dielectrically negative cholesteric liquid crystal,” Opt. Mat. Exp. 8, Pages: 691-697 (2018).
42. Wang, C.-Y. et al. All-optical transistor- and diode-action and logic gates based on anisotropic nonlinear responsive liquid crystal. Sci. Rep. 6, 30873; doi: 10.1038/srep30873 (2016).

C. Photorefractive effects, beam amplification and two beam coupling, dynamic/storage  holography
1. Coherent beam amplification and polarization switching in a birefringent medium-photorefractive crystals. I. C. Khoo, Yu Liang, and Hong Li, IEEE J. Quantum Electronics, JQE 28, pp. 1816-1824 (1992).
2. Onset dynamics of self-pumped phase conjugation from speckled noise. I. C. Khoo, N. Beldyugina, H. Li, A. V. Mamaev, and V. V. Shkunov, Optics Letters, 18, pp. 473-475 (1993).
39. Optically induced extraordinarily large negative orientational nonlinearity in dye-doped-liquid crystal. I. C. Khoo, H. Li, and Y. Liang, IEEE J. Quant. Electron, JQE29, pp. 1444-1447 (1993).
4. Self-starting optical phase conjugation in dyed nematic liquid crystals with a stimulated thermal-scattering effect. I. C. Khoo, H. Li and Y. Liang, Opt. Letts. 18, 1490 (1993).
5. Observation of orientational photorefractive effects in nematic liquid crystals. I. C. Khoo, H. Li, and Y. Liang, Optics Letts, 19, 1723 (1994).
6 I. C. Khoo, “Optical-dc-field induced space charge fields and photorefractive-like holographic grating formation in nematic liquid crystals,” Mol. Cryst. Liq. Cryst, 282, pp.53-66 (1996).
7. Orientational photorefractive effects in nematic liquid crystal film. I. C. Khoo, IEEE J. Quantum Electronics JQE 32, pp. 525-534 (1996).
8. Coherent beam amplification with photorefractive liquid crystal. I. C. Khoo, Brett D. Guenther, M. V. Wood, P. Chen and Min-Yi Shih, Opt. Lett. 22,1229 (1997).
9. Photorefractivity, Optical Wave Mixing and Holographic Grating Formation in Nematic Liquid Crystals. I. C. Khoo, Brett D. Guenther, S. Slussarenko, Mol. Cryst. Liq. Cryst., Vol. 321, pp 419- 438, 1998.
10. I. C. Khoo, M. V. Wood, B. D. Guenther, Min-Yi Shih, P. H. Chen, Zhaogen Chen and Xumu Zhang, “Liquid Crystal Film and Nonlinear Optical Liquid Cored Fiber Array for ps-cw Frequency Agile Laser Optical Limiting Application”. Optics Express, Vol. 2, no. 12. pp 471-82, (1998)
11. I. C. Khoo, M. V. Wood, M. Y. Shih and P. H. Chen, “Extremely Nonlinear Photosensitive Liquid Crystals for Image Sensing and Sensor Protection,” Optics Express, Vol. 4, no. 11, pp 431-442 (1999)
12. I. C. Khoo, Min-Yi Shih, M. V. Wood, B. D. Guenther, and P. H. Chen, F. Simoni, S. Slussarenko, O. Francescangeli, L. Lucchetti “Dye-doped photorefractive liquid crystals for dynamic and storage holographic grating formation and spatial light modulation” IEEE Proceedings Vol. 87, no. 11, pp 1897 – 1911 (1999).
13. M. Y. Shih, I. C. Khoo, A. Shishido, M. V. Wood, P. H. Chen, “All-Optical Image Processing with A Supra Nonlinear Dye-Doped Liquid Crystal Film”, Opt. Letts. 25, 978-980 (2000).
14. I. C. Khoo and Y. Liang, “Stimulated Orientational and Thermal Scatterings and Self-Starting Optical Phase Conjugation with Nematic Liquid Crystals,” Phys. Rev. E62, pp 6722 –6733 (2000).
15. I. C. Khoo, M. Y. Shih and A. Shishido, “Supra Optical Nonlinearities of Photosensitive Nematic Liquid Crystals,” Mole. Cryst. Liquid. Cryst. 364, 141-149, (2001).
16. I. C. Khoo and J. Ding, “All-optical cw laser polarization conversion at 1.55 micron by two beam coupling in nematic liquid crystal film,” Appl. Phys. Letts. 81, pp. 2496-2498 (2002).
17. I. C. Khoo, J. Ding, Y. Zhang, K. Chen and A. Diaz, “Supra-Nonlinear Photorefractive Response of Single-wall Carbon Nanotube- and C60-Doped Nematic Liquid Crysta1s,” Appl. Phys. Letts. 82, pp. 3587-3589 (2003).
18. I.C. Khoo and A. Diaz, “Nonlinear dynamics in laser polarization conversion by stimulated scattering in nematic liquid crystal films,” Phys. Rev. E68 pp 042701-1 to -4 [2003]
19. Iam Choon Khoo, Jianwu Ding, and Andres Diaz, “Dynamics of Cross-polarization Stimulated Orientation Scattering in Nematic Liquid Crystal Film,” J. Opt. Soc. Am. B 22, pp. 844-851 [2005]
20. I. C. Khoo, Yana Zhang Williams, B. Lewis and T. Mallouk, “Photorefractive CdSe and gold nanowire-doped liquid crystals and polymer-dispersed-liquid-crystal photonic crystals,” Mol. Cryst. Liq. Cryst. 446: 233-244 (2005).
21. I. C. Khoo, Kan Chen and Y. Zhang Williams, “Orientational Photorefractive Effect in undoped and CdSe Nano-Rods doped Nematic Liquid Crystal – Bulk and Interface Contributions,” IEEE J. Selected Topics in Quantum Electronics JSTQE 12 (3), pp. 443-450 [2006].

D. Tunable Photonic crystals, metamaterials, waveguide, micro-ring resonator, Purcell factor of quantum emitter in plasmonic structures
1. H. Vach, C. T. Seaton, G. I. Stegeman and I. C. Khoo, “Observation of intensity-dependent guided waves,” Opt. Letts., 9, 238-240 (1984).
2. I. C. Khoo, Yana Williams, Andres Diaz, Kan Chen, J. Bossard, D. Werner, E. Graugnard and C. J. Summers, “Liquid-Crystals for optical filters, switches and tunable negative index material development,” Molecular Crystal Liquid Crystal 453, pp.309-319 (2006).
3. I. C. Khoo, D. H. Werner, X. Liang, A. Diaz and B. Weiner, “Nano-sphere dispersed liquid crystals for tunable negative-zero-positive index of refraction in the optical and Terahertz regimes,” Optics Letts. 31, 2592 (2006)
4. D. H. Werner, D-H Kwon, I. C. Khoo, A. K. Kildeshev and V. M. Shalaev, “Liquid crystal-clad near-infrared metamaterials with tunable negative-zero-positive refractive indices,” Optics Express Vol. 15, No. 6, pp 3342-3347, 2007.
5. Shoichi Kubo, Andres Diaz, Yan Tang, Theresa S. Mayer, I. C. Khoo and Thomas E. Mallouk, “Tunability of the refractive index of gold nanoparticle dispersions,” NANO Letts. 7, pp. 3418-3423, (2007)
6. X. Wang, D. H. Kwon, D. H. Werner, I. C. Khoo, A. Kildishev and V. M. Shalaev, ‘Tunable optical negative-index metamaterials employing anisotropic liquid crystals,” Appl. Phys. Lett. 91, 143122 (2007).
7. I. C. Khoo, A. Diaz, S. Kubo, J. Liou, Mike Stinger, T. Mallouk and J. H. Park, “Nano-dispersed Organic Liquid and Liquid Crystals for All-Time-Scales Optical Switching and Tunable Negative- and Zero- Index Materials,” Molecular Crystals Liquid Crystals 485:1, pp. 934-944 (2008).
8. Bossard, J. A., Liang, X., Li, L., Werner, D. H., Weiner, B., Cristman, P. F., Diaz, A., & Khoo, I. C. (2008), “Tunable Frequency Selective Surfaces and Negative-Zero-Positive Index Metamaterials Based on Liquid Crystals,” IEEE Transactions on Antennas and Propagation, 56, pp. 1308 – 1320 (2008).
9. E. Graugnard, J. S. King, S. Jain, C. J. Summers, Y. Zhang-Williams and I. C. Khoo, “Electric field tuning of the Bragg peak in large-pore TiO2 inverse shell opals,” Phys. Rev. B72, 233105 (2005).
10. Shumin Xiao, Uday K. Chettiar, Alexander V. Kildishev, Vladimir Drachev, I. C. Khoo and Vladimir M. Shalaev, “Tunable Magnetic Response of Metamaterials,” Appl. Phys. Lett.Vol. 95 Issue: 3 Article Number: 033115 (2009).
11. A. Diaz and I. C. Khoo, “Liquid crystalline nano-structured optical metamaterials,” in Comprehensive Nanoscience and Technology, Vol. 3, pages 225-261 eds. David Andrews, Gregory Scholes and Gary Wiederrecht [Elseier, 2011]
12. Yan Jun Liu, Qingzhen Hao, Joseph S. T. Smalley, Justin Liou, Iam Choon Khoo, and Tony Jun Huang, “A Frequency-Addressed Plasmonic Switch Based on Dual-Frequency Liquid Crystal,” Appl. Phys. Letts. 97, issue 9, article #: 091101 (2010)
13. Antonio d’Alessandro, Rita Asquini, Marco Trotta, Giovanni Gilardi, Romeo Beccherelli, and Iam Choon Khoo, “All-optical intensity modulation of near infrared light in a liquid crystal channel waveguide,” Appl. Phys. Letts. 97, issue 9, article #: 093302 (2010)
14. Tony J. Huang, Y. J. Liu, B. Yue, J. Liou and I. C. Khoo, “All-Optical Modulation of Localized Surface Plasmon Coupling in a Hybrid System Composed of Photo-Switchable Gratings and Au Nanodisk Arrays,” Journal of Physical Chemistry 115 Issue: 15 Pages: 7717-7722 (2011)
15. Li Jia; Ma Yi; Gu Ying; Q. Gong and I. C. Khoo et al, “Large spectral tunability of narrow geometric resonances of periodic arrays of metallic nanoparticles in a nematic liquid crystal,” Appl. Phys. Letts., 98 Issue: 21 Article Number: 213101 (2011)
16. Zhang Bingxin; Zhao Yanhui; Hao Qingzhen, I. C. Khoo, “Polarization-independent dual-band infrared perfect absorber based on a metal-dielectric-metal elliptical nanodisk array,” Opt. Express 19 Pages: 15221-15228 (2011)
17. Smalley Joseph S. T.; Zhao Yanhui; Nawaz Ahmad Ahsan; I. C. Khoo; Tony Huang, “High contrast modulation of plasmonic signals using nanoscale dual-frequency liquid crystals,” Opt. Express 19, Pages: 15265-15274 (2011)
18. Hao Qingzhen; Zhao Yanhui; Juluri Bala Krishna, I. C. Khoo and tony Huang, “Frequency-addressed tunable transmission in optically thin metallic nanohole arrays with dual-frequency liquid crystals, J. Appl. Phys. Volume: 109 Issue: 8 Article Number: 084340 (2011).
19. G. Pawlik, K. Tarnowski, W. Walasik, A.C. Mitus and I.C. Khoo, “Infrared cylindrical cloak in nanosphere dispersed liquid crystal metamaterial,” Optics Letters 37, pp. 1847-1849 (2012)
20. I. C. Khoo, A. Diaz, J. Liou, M. V. Stinger, J. Huang and Y. Ma, “Liquid Crystals Tunable Optical Metamaterials,” IEEE J. Selected Topics in Quantum Electronics, Special Issue Vol. 16, pp. 410-417 (2010)
21. Y. Zhao, Q. Z. Hao, Y. Ma, M. Q. Lu, B. X. Zhang, M. Lapsley, I. C. Khoo and T. J. Huang, “Light-driven tunable dual band absorber with liquid-crystal-plasmonic asymmetric nanodisk array,” Appl. Phys. Letts.100, Article # 053119 (2012)
22. G. Pawlik, W. Walasik, K. Tarnowski, A. C. Mitus, I. C. Khoo, “Liquid crystal hyperbolic metamaterial for wide-angle negative-positive refraction and reflection,” Optics Letters, Vol. 39, Issue 7, pp. 1744-1747 (2014)
23. Rui Luo, Ying Gu, Xiankuo Li, Luojia Wang, Iam-Choon Khoo, and Qihuang Gong, “Mode recombination and alternation of surface plasmons in anisotropic mediums,” Appl. Phys. Letts. 102, 011117 (2013)
24. Joanna Ptasinski, Sung W. Kim, Lin Pang, Iam-Choon Khoo, and Yeshaiahu Fainman, “Optical tuning of silicon photonic structures with nematic liquid crystal claddings,” Optics Letters Vol. 38, Iss. 12, pp. 2008–2010 (2013).
25. Joanna Ptasinski, Iam-Choon Khoo and Yeshaiahu Fainman, “Passive Temperature Stabilization of Silicon Photonic Devices Using Liquid Crystals,” Materials 2014, 7(3), 2229-2241
26. Joanna Ptasinski, Iam-Choon Khoo, and Yeshaiahu Fainman, “Enhanced optical tuning of modified-geometry resonators clad in blue phase liquid crystals,” Optics Letts. Volume: 39 Pages: 5435-5438 (2014)
27. Hao, He; Ren, Juanjuan; Chen, Hongyi; Khoo, Iam Choon; Gu, Ying; Gong, Qihuang, “Tunable enhanced spontaneous emission in plasmonic waveguide cladded with liquid crystal and low-index metamaterial,” Optics Express 25(4) 3433-3444 (2017).
28. He Hao, Juanjuan Ren, Xueke Duan, Guowei Lu, Iam Choon Khoo, Qihuang Gong and Ying Gu, “High-contrast switching and high-eciency extracting for spontaneous emission based on tunable gap surface plasmon”, Sci. Rep. | (2018) 8:11244 | DOI:10.1038/s41598-018-29624-y.

E. Nanoseconds-picoseconds-femtoseconds nonlinear optical processes and ultrafast all-optical switching
1. Theory and experiment on optically induced nematics axis reorientation and nonlinear effects in the nanosecond regime. I. C. Khoo, R. R. Michael and P. Y. Yan, IEEE J. Quant. Electronics, QE23, 267 (1987).
2. Simultaneous occurrence of phase conjugation and pulse compression in stimulated scatterings in liquid crystal mesophases. I. C. Khoo, R. R. Michael and P. Y. Yan, IEEE J. Quant. Elect., QE23, 1344 (1987).
3. A quantitative analysis of picosecond transient multiwave mixings mediated beam amplification effect in silicon. I. C. Khoo, P. Zhou, R. G. Lindquist and P. LoPresti, Phys. Rev., A41, 408 (1990).
4. I. C. Khoo, R. G. Lindquist, R. R. Michael, R. J. Mansfield and P. Lopresti, “Dynamics of picosecond laser induced density, temperature and flow-reorientation effects in the mesophases of liquid crystals,” J. Appl. Phys., 69, 3853-3859 (1991).
5. I. C. Khoo, “Laser induced thermal, orientational and density nonlinear optical effects in nematic liquid crystal,” Phys. Rev. A, 42, 1001-1004 (July 1990).
6. Observation of optical limiting and backscattering of nanosecond laser pulses in liquid crystal fibers. I. C. Khoo, H. Li and Y. Liang, Optics Letts. 19, 530 (1994).
7. I. C. Khoo and H. Li, “Nonlinear optical propagation and self-limiting effect in liquid crystalline fiber,” Appl. Phys. B59, pp: 573-580 (1994).
8. Nonlinear Liquid Crystal Fiber Structures for Passive Optical Limiting of Short Laser Pulses. I. C. Khoo, M. V. Wood, M. Lee and Brett D. Guenther. Optics Letters 21, 1625 -1627 (1996).
9. I. C. Khoo, M. V. Wood, B. D. Guenther, Min-Yi Shih and P. H. Chen, “Nonlinear- absorption and optical limiting of laser pulses in a liquid-cored fiber array,” J. Opt. Soc. Am. B15, pp. 1533-1540, (1998).
10. I. C. Khoo, P. H. Chen, M. V. Wood, and Min-Yi Shih, “Molecular photonics of a highly nonlinear organic fiber core liquid for picosecond -nanosecond optical limiting effect”, Chemical Physics Vol. 245, pp. 517-531(1999).
11. I.C. Khoo, Andres Diaz and J. Ding, “Nonlinear-absorbing Fiber Array for Large Dynamic Range Optical Limiting Application against Intense Short Laser Pulses, J. Opt. Soc. Am B21, pp. 1234-1240 [2004].
12. I. C. Khoo, Jae-Hong Park and Justin Liou, “All-optical Switching of Continuous Wave Microseconds Lasers with a Dye-doped Nematic Liquid Crystal,” Appl. Phys. Letts. 90, 151107 (2007).
13. I. C. Khoo, “Nonlinear Organic Liquid Cored Fiber Array for All- Optical Switching and Sensor Protection against Short Pulsed Lasers,” IEEE J. Selected Topics in Quantum Electronics JSTQE 14, no. 3, pp 946 – 951 (2008)
14. I. C. Khoo, J. H. Park, J. D. Liou, “Theory and experimental studies of all-optical transmission switching in a twist-alignment dye-doped nematic liquid crystal,” J. Opt. Soc. Am. B25, pp. 1931-1937 (2008)
15. I.C. Khoo, S. Webster, S. Kubo, W. J. Youngblood, J. Liou, A. Diaz, T. E. Mallouk, P. Lin, D. Peceli, L. A. Padilha, D. J. Hagan, and E. W. Van Stryland, “Synthesis and characterization of the multi-photon absorption and excited-state properties of 4-propyl 4′-butyl diphenyl acetylene,” J. Mater. Chem. 19, 7525-7531 (2009)
16. I. C. Khoo, J. Liou and M. V. Stinger, “Microseconds-Nanoseconds All-Optical Switching of Visible-Near Infrared (0.5 um-1.55 um) Lasers with Dye-Doped Nematic Liquid Crystals,” Mole. Cryst. Liq. Cryst. 527, pp. 109-118 (2010).
17. I. C. Khoo and A. Diaz, “Multiple-time-scales dynamical studies of nonlinear transmission of pulsed lasers in a multi-photon absorbing organic material,” J. Opt. Soc. Am B28 Issue: 7 Pages: 1702-1710 (2011)
18. Khoo I. C.; Liou J.; Stinger M. V.; S. Zhao, “Ultrafast All-Optical Switching with Transparent and Absorptive Nematic Liquid Crystals-Implications in Tunable Metamaterials,” Mol. Cryst. Liq. Cryst. 543 Pages: 151-159 (2011)
19. I. C. Khoo and S. Zhao, “Multiple Time Scales Optical Nonlinearities of Liquid Crystals for Optical-Terahertz-Microwave Applications,” Progress in Electromagnetic Research PIER, Vol. 147, page 37-56, 2014
20. Liu, Yikun; Fu, Shenhe; Malomed, Boris A.; Khoo, Iam Choon: Zhou, Jianying, “Ultrafast optical signal processing with Bragg structures,” Appl. Sci. 2017, 7, 556 doi:10.3390/app7060556
21. Chun-Wei Chen, Xue Guo, Xingjie Ni, Tsung-Hsien Lin and Iam Choon Khoo “Slowing ultrafast (600 femtoseconds) laser pulse with a 550μm-thick cholesteric liquid crystal,” Optical Materials Express, Vol. 7, Issue 6, pp. 2005-2011 (2017)
22. Liyan Song, Shenhe Fu, Yikun Liu, Jianying Zhou, Vladimir G. Chigrinov, and Iam Choon Khoo, “Direct femtosecond pulse compression with miniature-sized Bragg cholesteric liquid crystal,” Optics Letters 38, pp 5040 – 5042 (2013).
23. Yikun Liu, You Wu, Chun-Wei Chen, Jianying Zhou, Tsung-Hsien Lin, and Iam Choon Khoo, “Ultrafast pulse compression, stretching-and-recompression using cholesteric liquid crystals,” Optics Express, Vol. 24, Issue 10, pp. 10458-10465 (2016)
24. Iam Choon Khoo (2018) Cholesteric and blue-phase liquid photonic crystals for nonlinear optics and ultrafast laser pulse modulations, Liquid Crystals Reviews, 2018. DOI: 10.1080/21680396.2018.1509387
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Conference Presentations 423 [*Invited: 230; ** Keynote/Plenary: 33]
**69. Multiwave mixings-theory and experiments. I. C. Khoo, Invited Plenary Talk . International Conference on Nonlinear Optics, Ashford Castle, Ireland (May 1988).
**229. I. C. Khoo, “Photorefractivity in Liquid Crystals,” Invited Plenary Seminar [Sturgeon Memorial Lecture] at 2003 British Liquid Crystals Society Annual Meeting, Fitzwilliam college, Cambridge University, April 7-10, 2003.
**240. I. C. Khoo, “Ultra-large Dynamic Range Nonlinear Absorption Materials” International Conference on Photoresponsive Organics and Polymers, Busan, Korea, Feb. 16-20 (2004).
**247. I. C. Khoo, “Nonlinear molecular photonics and controlled laser transmission through a nonlinear fiber array,” SPIE European Symposium on Optics and Photonics for Defense and Security, London, Oct. 2004
** 271. I. C. Khoo, Invited Keynote Presentation. “Low loss reconfigurable metallo-dielectric and all-dielectric frequency selective surfaces and metamaterials for optical filters and switching applications”. International Symposium on Bio-Photonics, Nano-Photonics and Metamaterials, Hangzhou, China Oct. 16-19, 2006.
**274. I. C. Khoo. Invited Plenary Presentation, “Liquid Crystalline Metamaterials with Low-Loss Tunable Negative-Zero-Positive Refractive Index in the Terahertz –Optical Region,” SPIE Europe – International Congress on Optics and Optoelectronics 16 – 20 April 2007 Prague, Czech Republic
** 278. I. C. Khoo, Invited Plenary Presentation, “Nano-dispersed Organic Liquid and Liquid Crystals for All-Time-Scales Optical Switching and Tunable Negative- and Zero- Index Materials,” at the 9th International Conference on Frontiers of Polymers and Advanced Materials,” Krakow, Poland 7/8 – 7/13, 2007
**297. I. C. Khoo, “Liquid crystal nonlinear optical meta-materials,” Invited Keynote Plenary Presentation – 2nd Int. Workshop on Liquid Crystals for Photonics,” July 21-23 Cambridge University, Cambridge, UK (2008)
**301. I. C. Khoo, “Reconfigurable/Tunable Negative-Zero (and Low or novel) Index Optical Metamaterials,” Invited Plenary Presentation, Int. School of Liquid Crystals, Erice, Italy. 10/27 – 11/1, 2008
**303. I. C. Khoo, “All-optical Nonlinear Transmission Control – Materials and Devices Development for Multiple Time-Scales and Spectral-Bands Application,” Invited Keynote Lecture, International Symposium on Materials and Devices for Nonlinear Optics, Isle Proquerolles, France on June 26 – July 1, 2009.
**307. I. C. Khoo, “Nonlinear Optics of Liquid Crystals,” Invited Keynote Plenary Paper – International Topical Meeting on Optics of Liquid Crystals, Erice, Italy Sept. 30, 2009.
**317. I. C. Khoo, Invited Keynote Paper, “Multiple-Time-Scales Dynamical Studies of Multi-Photon Nonlinear Absorbers for Passive All-Optical Sensor Protection, European Symposium on Security and Defense, Toulouse, France Sept. 20-23 (2010).
**321. I. C. Khoo, Invited Plenary Presentation, “Liquid-Crystals-Plasmonic Metamaterials for High-Speed All-Optical Processing” in International Metamaterials Workshop, Hangzhou, China, 4/2011
**327. I. C. Khoo, Invited Keynote Lecture, “Plasmonic-liquid-crystals for advanced electro- and nonlinear-optics,” International Workshop on Nano- and Bio-Photonics [IWNBP], Lyon, France, Oct. 23th -28th, 2011
**329. I. C. Khoo, S. Zhao, Yi Ma and K. L. Hong “Liquid crystals with embedded plasmonic particulates and nanostructures”, Invited Plenary Paper – Symposium on Liquid Crystal Photonics, Guilin, China 3-23-3-27, 2012
**330. I. C. Khoo, “Stimulated cross-polarization scattering and nonlinear dynamics in nematic liquid crystals,” Invited Keynote paper – Nonlinear Guided Waves VI –Santiago de Compostella, Spain, May 7-9, 2012
**338. I. C. Khoo, “Blue-Phase Liquid Crystalline Photonic Materials and Nanostructures,” Invited Keynote Presentation, Third International Workshop on Advanced Nano- and Biomaterials and Their Device Applications, organized jointly with French-Romanian Topical Meeting on Nano and Biomaterials, Timisoara (Romania), September 19-23, 2012
**343. I. C. Khoo, Plenary Speaker “Photonics of Liquid Crystalline Materials/Nanostructures,” Taiwan National Liquid Crystal Society Annual Meeting. December 22, Kaohsiung, Taiwan. 2012
**344. I. C. Khoo, Plenary Speaker “Nonlinear Optics of Blue Phase Liquid Crystals,” Invited Plenary speaker in Symposium on Liquid Crystals Photonics 2013, Chengdu, China April 20 – 25, 2013.
**352. I. C. Khoo, “Nonlinear Optics of Liquid Crystals Visible – THz – and Beyond” Keynote Presentation in Progress In Electromagnetics Research Symposium PIERS 2013, Stockholm, Sweden, 12-15 August, 2013.
**356. I. C. Khoo, “Ultrafast nonlinear optics, tunable plasmonics and tunable matamaterials,” Invited Keynote Presentation in Symposium Liquid Crystals Photonics, Shanghai, China April 19-23 (2014)
**360. I. C. Khoo, “Ultrafast Nonlinear Optics, Tunable Metamaterials and Active Plasmonics with Liquid Crys” Invited Keynote Presentation, Conference on Advanced Material Science and Engineering, Shanghai, 10/21/2014.
**367. I. C. Khoo, “Liquid Crystalline Materials for Optical Switching with Femtoseconds – CW Lasers” Invited Keynote Presentation at ‘Progress in Electromagnetic Research Symposium” PIERS 2015, Prague, Czech Republic July 5-9, 2015.
**376. I. C. Khoo, “Liquid crystals for tunable nano-plasmonics,-metamaterials and femtoseconds laser
pulse modulations,” Invited Keynote Presentation, NICE Optics, NICE, France 10/26 – 10/28, 2016
**377. I. C. Khoo, “Femtoseconds pulse modulations and high efficiency holographic grating with tunable memory with liquid crystals” Invited Keynote Presentation, International Conference on Frontier of Polymers and
**388 I. C. Khoo, “Femtoseconds-Picoseconds Nonlinear Optics and Photonics with Liquid Crystals” Keynote Invited Presentation, Symposium on Liquid Crystal Photonics (SLCP), Tianjin, China May 3-6, 2017
**389 I. C. Khoo, Chun-Wei Chen, Yizhu Chen, Zhiwen Liu “Ultrafast [Femtoseconds – Picoseconds] Nonlinear optics with extraordinarily large nonlinearities of liquid crystalline photonic crystals,” Keynote Invited Presentation, Progress in Electromagnetics Research (PIERS), St. Petersburg, Russia 5-21-5/25, 2017
**399. (Invited Keynote) I. C. Khoo, Tsung-Jui Ho and Chun-Wei Chen, “Laser induced lattice distortion of Blue Phase liquid crystal for high efficiency and high-resolution real time and storage holography,” Progress in Electromagnetic Research (PIERS), Singapore 12/2017
**410. I. C. Khoo and C. W. Chen, “Liquid crystalline photonics crystals of super-dimensions for advanced photonic application,” Invited Keynote Presentation, Photonics and Electromagnetic Research Symposium (PIERS), Rome, Italy 6/16 -6/20 [2019]
**417. I. C. Khoo, “Engineering and advanced applications of super-dimensional liquid-crystalline photonic crystals,” Invited Keynote Presentation, SPIE Defense and Security Symposium, Strasbourg, France 9/9 – 9/13 [2019]
**422. I. C. Khoo “Liquid crystalline chiral photonic crystals for ultrafast (linear and nonlinear) photonics,” Invited Plenary Lecturer. Optics of Liquid Crystals Conference, Okinawa, Japan 9/26 – 10/1, [2021].
**427. I. C. Khoo “Liquid Crystalline Chiral Photonic Crystals for Ultrafast and Advanced Photonics,” Plenary Presentation, 3rd International Congress on Advanced Materials Sciences and Engineering, Opatija, Croatia 7/21-7/25, 2022.
**428. I. C. Khoo, “Liquid Crystalline Chiral Photonic Crystals for Ultrafast Vector Laser Beams,” Keynote Presentation, 6^th International Workshops on Nano and Bio-Photonics, Evian, France 9/25 – 9/30, 2022.
** 433. I. C. Khoo, “Liquid crystalline chiral photonic crystals for visible to mid-IR polarization switching and pulse modulation,” Plenary Presentation, 20th Optics of Liquid Crystals Conference, Szczecin, Poland 9/17-9/22, 2023.
**435. I. C. Khoo, “Liquid crystalline chiral photonic crystals.” Keynote Presentation, The 2nd International Responsive Materials Symposium, May 17-25, 2024| Nanjing, China.
**437. I. C. Khoo, “Chiral Soft-Matter Photonic Crystals For Advanced Reconfigurable Photonic Applications.” Plenary Presentation, 2nd International Congress And Expo On Materials Science & Nanoscience June 13-15, 2024 | Nice, France

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