Program for Promoting Academic Excellence of Universities

Development of Optical-MEMS for Light Modulation

....Micro-Electro-Mechanical-System (MEMS) is a rapidly developing technology with promising applications to optical switching fabrics, optical sensors, displays, micro-actuators etc. The purpose of the subproject is to utilize MEMS technology to fabricate miniature optical components and systems for light modulation. Major tasks include (1) a micro-heterodyne-interferometer using an unconventional sinusoidal modulation scheme and a new signal-processing algorithm and (2) High efficiency electro-optic light modulator based on waveguide-coupled surface plasmon resonance.

....A new type of heterodyne interferometry based on a micro-grating mirror which is modulated in sinusoidal signal is first proposed. In this study a new algorithm for modulating a micro-grating mirror using a sine-wave signal instead of a saw-tooth signal is proposed in order to resolve the flyback problem in a PZT driver. An improved synthetic heterodyne demodulator circuit is designed and arranged to interrogate the output signal from an interferometric sensor with a sine-wave modulation (phase-generated carrier). As compared to the conventional technique, modulating the PZT stack in a saw-tooth signal, this technique supplies a wider modulated frequency and, therefore, a wider frequency response in a sensing system. Finally, the new synthetic heterodyne will be applied to a micro-optics bench as a micro interferometry.

....The second target of the proposed study is to design and fabricate a novel high-efficiency electro-optic (E-O) light modulator whose operation is based on the attenuated total reflection (ATR) effect, in which the surface plasmon wave (SPW) is excited by an incident waveguide-coupled light wave. The E-O light modulator is fabricated using a non-linear optical (NLO) polymer. The modulator is characterized, and its performance tested, in terms of the thickness and dielectric constant of the polymer thin film, the E-O coefficient, the insertion loss, and the modulation index. Additionally, the dynamic response of the E-O light modulator is fully investigated and discussed. Also, we demonstrate FM/FDM analog video communication system using this E-O polymer light modulator as light transmitter.

....The major focuses in the second year include:
1. Design and fabrication of microactuators and several micro mirrors. Several critical micro optical components have been achieved.
2. Simulation of microactuators
3. Design and fabricate a novel high-efficiency E-O polymer light modulator. Also, a FM/FDM analog video communication system is demonstrated by using this E-O polymer light modulator.