Yuh-Jing Hwang

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We demonstrate a room-temperature-operated all-terahertz (THz) fiber-scanning near-field imaging system. The upright-type THz near-field microscope has a compact size, capable of being integrated with an optical microscope. This transmission illumination near-field system could be a promising tool to distinguish breast cancer from the normal tissue without(More)
We performed in vivo THz transmission imaging study on a subcutaneous xenograft mouse model for early human breast cancer detection. With a THz-fiber-scanning transmission imaging system, we continuously monitored the growth of human breast cancer in mice. Our in vivo study not only indicates that THz transmission imaging can distinguish cancer from the(More)
a W-band subharmonically pumped (SHP) diode mixer module is designed, fabricated and tested for broadband astronomical applications. The packaged module performance is measured and compared under room-temperature and cryogenic environment. In summary, compared to the room-temperature performance, when the SHP diode mixer is operated under cryogenic(More)
Two subharmonically pumped (SHP) diode mixers are designed for wideband W-band RF frequencies, fixed LO frequency operation. These mixers are fabricated on a 4-mil substrate using 0.1-μm GaAs MMIC process. Both simulation and test results show that the mixers are with 12.25 and 11.75 dB average conversion losses, respectively. Both mixers have IF bandwidth(More)
We demonstrate a new reflective imaging technique using continuous-wave THz fiber-endoscopy, in which the sample is placed behind the output of a THz subwavelength plastic fiber and the Fabry Perot interference is formed therein. 3D THz reflective images with a reasonable SNR as well as high lateral and subwavelength axial resolutions are acquired by moving(More)
Design and cryogenic operation of an intermediate frequency (IF) low noise amplifier using a 0.15-µm InGaAs mHEMT process for Atacama Large Millimeter/Submillimeter Array (ALMA) is presented in this paper. The amplifier covers 4–12 GHz with small signal gain of 27±2 dB and effective noise temperature of 18–25 K when operating at(More)
We present an experimental study on the bending loss of terahertz (THz) pipe waveguide. Bending loss of pipe waveguides is investigated for various frequencies, polarizations, core diameters, cladding thicknesses, and cladding materials. Our results indicate that the pipe waveguides with lower guiding loss suffer lower bending loss due to stronger mode(More)
A phase-locked broadband GaAs HBT voltage controlled oscillator module is designed, fabricated and tested for the local oscillators in millimetre-wave astronomical heterodyne receivers. The configuration of the local oscillator module is based on the offset phase-locked loop scheme with frequency dividing circuit in the feedback path. Employing closed-loop(More)
We experimentally demonstrate a terahertz (THz) leaky mode directional coupler for future THz applications. The proposed directional coupler comprises two square pipe waveguides. The coupling efficiency is investigated for different frequencies, polarizations, and core sizes. Rectangular pipe-waveguide-based directional couplers and the issue of insertion(More)