T. Zhong

Nanyang Technological University, Singapore, Singapore

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Publications (7)11.11 Total impact

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    ABSTRACT: This paper presents a thermooptic switch based on the optical tunneling effect of a double optical barriers system. By introducing a new physical mechanism of the optical tunneling effect into micro-electro-mechanical systems (MEMS) technology, a switching contrast of more than 30 dB with a response time of less than 3 mus are obtained. Compared with the previously reported thermo-optic switches, this design requires very small change in refractive index for switching (Deltan ap 10<sup>-4</sup>), which is only 1/10 of the typical requirement. It has fast tuning speed and low power consumption.
    Micro Electro Mechanical Systems, 2008. MEMS 2008. IEEE 21st International Conference on; 02/2008
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    ABSTRACT: This letter demonstrates the thermo-optic switching function using an adjustable optical well structure, which is constructed by a thin air gap sandwiched between two micromachined hemicylindrical prisms. The device is etched on a silicon-on-insulator wafer within a footprint of 400×400 μ m <sup>2</sup> . In experiment, it measures an extinction ratio of 30.2 dB and a switching time of 2.2 μ s . Compared with the other demonstrated switches that have optical barrier structures, this device is unique in the working principle and optical design, and shows various merits such as high extinction ratio, fast speed, low power consumption, and small size.
    Applied Physics Letters 01/2008; · 3.52 Impact Factor
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    T. Zhong, X.M. Zhang, H. Cai, A.Q. Liu
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    ABSTRACT: This paper reports a design of double micromachined silicon cylindrical prisms separated by a thin air gap to enable fast thermo-optic switching. The fabricated structure has obtained an extinction ratio of 29.8 dB. This design is advantageous over conventional micromechanical switches for the absence of mechanical stability problems. The use of total internal reflection significantly enhances the sensitivity of switching to small refractive index change of only 5.2 times 10<sup>-3</sup>, which allows an on-off switching at 2.2 mus by localized heating through a thermal resistor patterned on top of the prism.
    Solid-State Sensors, Actuators and Microsystems Conference, 2007. TRANSDUCERS 2007. International; 07/2007
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    ABSTRACT: This paper presented the design of subwavelength grating (i.e., nano-grating) for narrow-band and wide-band filter applications. The grating period can be tuned from 700 nm to 1140 nm by a rhombic-shaped thermal actuator array with a driving current of 2.7 mA, achieving a change of transmissivity by 13 dB due to the guided mode resonance. Wide-band of filtering can be obtained by use of another fixed-period grating to compensate the dispersion. Such grating design makes it practical to implement many tunable nano-optical devices.
    Solid-State Sensors, Actuators and Microsystems Conference, 2007. TRANSDUCERS 2007. International; 07/2007
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    ABSTRACT: This paper reports the conceptual design and experimental demonstration of an optical switch that utilizes the thermo-optic effect (TOE) and total internal reflection (TIR) of a micromachined silicon prism. The key idea is to change the refractive index of the prism via TOE to switch the light from the transmission state to the TIR state. The structure is fabricated by microelectromechanical systems (MEMS) technology on a silicon-on-insulator wafer. It requires a temperature change of 69 K to switch from the transmission to the reflection states, which measure isolations of 15.6 and 40.1 dB, respectively. This design is advantageous over the other waveguide switches and photonic crystal devices in the aspects of the absence of beam splitting, tremendously enhanced sensitivity of switching to small change in refractive index, high compactness, and potentially fast and low power switching
    IEEE Journal of Selected Topics in Quantum Electronics 04/2007; · 4.08 Impact Factor
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    ABSTRACT: This letter presents an optical switch using total internal reflection (TIR) via thermo-optic effect (TOE). The switching function is obtained by changing the refractive index of silicon prism via TOE to switch the light across the TIR state. The structure is fabricated by microelectromechanical systems technology. The switch measures a cross talk of >30 dB and an extinction ratio of >40 dB but exhibits high insertion losses of 31.67 and 18.95 dB in the TIR and transmission states, respectively. Compared with conventional micromechanical and light-tuned switches, this switch is unique in mechanism and free of mechanical instability.
    Applied Physics Letters 06/2006; 88(24):243501-243501-3. · 3.52 Impact Factor
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    ABSTRACT: This paper reports a new optical switching design using a pair of micromachined silicon hemispheres by means of thermo-optic effect (TOE) and total internal reflection (TIR). This design is advantageous over conventional micromechanical switches for absence of mechanical movements and thus high reliability
    01/2006;