| Assoc Prof (Adj) Phua Poh Boon
Adjunct Associate Professor
Division of Physics & Applied Physics
School of Physical & Mathematical Sciences
College of Science
Email: POHBOON@ntu.edu.sg
Phone: (+65)63162965
Office: SPMS-PAP-03-13 |
| Education |
- PhD Massachusetts Institute of Technology 2004
- MSc National University of Singapore 1998
- BSc(Hons) National University of Singapore 1995
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| Biography |
Educational Background
2000 - 2004
Ph.D (Electrical Engineering & Computer Science)
Massachusetts Institute of Technology
Thesis Title: "Deterministic Approach To Polarization Mode Dispersion."
Thesis Advisors:
1) Professor Hermann A. Haus (Institute Professor)
2) Professor Erich P. Ippen (Elihu Thomson Professor of Electrical Engineering)
1997 - 1998
Master of Engineering (Part-Time)
(Electrical Engineering),
National University of Singapore
Thesis Title: "Mid Infrared Optical Parametric Oscillator"
Thesis Advisor : Professor Chong Tow Chong
1991 - 1995
Bachelor of Science in Physics (First Class Honours), National University of Singapore
1987 - 1988
Temasek Junior College
Working Experience
1995 - present
DSO National Laboratories, Singapore (Principal Member of Technical Staff)
2005 - present
Nanyang Technological University (Adjunct Assistant Professor)
Teaching Experience
Teaching Assistant for MIT Course EE 6.631
"Optics and Optical Electronics" (Professor Fujimoto). (2003 Fall)
Lecturer for NTU Course PAP 181
"Foundations of Physics I" (2005 and 2006 Fall)
Lecturer for NTU Course PAP 462
“Quantum Electronics” (2008 Spring) |
| Research Interests |
1. Ultrafast Femtosecond Lasers: The Gears for Future Optical Clocks
All clocks require two components: (1) a regular periodic event such as the swing of the pendulum and (2) a way of recording the events, such as the step by step movement of gears attached to the minutes hands of a clock. In an optical clock, the oscillation of an ultracold-atom is used as the pendulum while the pulses of the femtosecond lasers is used as the ?gears and hands? to count the oscillations. Such an optical clock has the potential of >1000 more accurate than the current Cesium clock used by the International Time Standard. The accuracy is so good that the optical clock might gain or lose a second in 4 billion years.
In this project, we explore the use of femto-second laser to generate a broadband stable frequency comb. This stable comb will play a critical role in the next generation of atomics clocks based on optical frequencies. Due to the few orders of magnitude higher frequency involved in optical transition in optical clock, as compared to the microwave transition used in the Cesium clock, the precision of optical clock can be several orders more accurate than the Cesium clock. However, these high optical frequencies make it difficult to count cycles as required for comparison to the current Cesium microwave standard. A stable optical frequency comb from a femto-second laser can effectively acts as an optical-to-microwave conversion tool to perform the clockwork for these optical atomic clocks. It is currently a hot research topic pursued by many research groups throughout the world, such as MIT, NIST and JILA.
2. Radially Polarized Lasers: Breaking the limit of diffraction
Focusing an incoming light into a smaller spot is always one of the most interesting topics for optical engineers and scientists. This is highly motivated by the large number of optical instruments and devices that makes use of a sharply focused light beam. A tighter focus means better resolution for applications such as lithography, laser machining and confocal microscopy, and higher storage density for optical data storage applications. It has been shown experimentally that a radially polarized laser beam, under suitable conditions, can be focussed tighter than the diffraction limit. The project explores a novel method to generate a high-power radially polarized laser beam.
3. Tunable Solid State Lasers:
Near-infrared pumped solid state lasers such as Cr:YAG and Cr:Forsterite are of interest because they enable the implementation of broadly tunable continuous-wave sources or the generation of short temporal optical pulses in the 1 micron to 1.6 micron spectral range. This emission spectrum is useful as it covers the telecommunication range. The project designs and builds a high power tunable single longitudinal mode Cr:YAG laser.
4. Diode Pumped Solid State Laser:
Diode pumping of laser offers better efficiency and beam quality than the flashlamp pumped configurations. We have interests in exploring novel configurations of diode pumping and the diode pumping of novel solid-state active media. Our previous works on diode pumped solid state laser include Nd:YAG, Nd:YVO4, Nd:YALO, Tm:YAG, Yb:YAG and several Yb-doped fiber lasers.
5. Nonlinear conversion of laser wavelength:
Optical Parametric Oscillator is a convenient method to generate wavelengths that are not accessible by the solid state lasers. We have interests and have spent substantial research effort in the development of high power mid-IR Optical Parametric Oscillator based on nonlinear optical crystals such as ZnGeP2, KTP, KTA, AgGaS2, and AgGaSe2.
6. Passive/Active locking of lasers:
Passive or active coherent locking of lasers promises large laser power scalability. We are currently exploring a novel scheme of coherent locking of several high power Nd lasers. |
| Research Grant |
- Defence Science Organisation National Laboratories (-) [by MINDEF - DSO National Laboratories]
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| Current Projects |
- Thales Liquid Crystal Light Valve
| Selected Publications | - P.B. Phua and W.J. Lai. (2007). Simple Coherent Polarization Manipulation Scheme for Generating High Power Radially Polarized Beam. Optics Express, 15(21), 14251?14256.
- P.B. Phua, W.J. Lai, K.S. Tiaw, B.C. Lim, H.H. Teo, Y.L. Lim and M.H. Hong. (2007). Mimicking Optical Activity for Generating Radially Polarized Light. Optics Letters, 32(4), 376-378.
- P.B. Phua, B.S. Tan, R.F Wu, K.S. Lai, Lindy Chia, Ernest Lau. (2006). High Average Power Mid IR ZnGeP2 OPO using Wavelength Dependent Polarization Rotator. Optics Letters, 31(4), 489.
- P. B. Phua and H. A. Haus. (2002). Variable Differential-Group-Delay Module Without Second-Order PMD. Journal of Lightwave Technology, 20(9), 1788.
- P.B. Phua, K.S. Lai , R.F. Wu and T.C. Chong. (1998). Coupled tandem optical parametric oscillator (OPO) : an OPO within an OPO. Optics Letters, 23(16), 1262.
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