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Dive into the research topics where Guangyao Liu is active.

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Featured researches published by Guangyao Liu.


Optics Express | 2017

Rapidly reconfigurable high-fidelity optical arbitrary waveform generation in heterogeneous photonic integrated circuits

Shaoqi Feng; Chuan Qin; Kuanping Shang; Shibnath Pathak; Weicheng Lai; Binbin Guan; Matthew Clements; Tiehui Su; Guangyao Liu; Hongbo Lu; Ryan P. Scott; S. J. Ben Yoo

This paper demonstrates rapidly reconfigurable, high-fidelity optical arbitrary waveform generation (OAWG) in a heterogeneous photonic integrated circuit (PIC). The heterogeneous PIC combines advantages of high-speed indium phosphide (InP) modulators and low-loss, high-contrast silicon nitride (Si3N4) arrayed waveguide gratings (AWGs) so that high-fidelity optical waveform syntheses with rapid waveform updates are possible. The generated optical waveforms spanned a 160 GHz spectral bandwidth starting from an optical frequency comb consisting of eight comb lines separated by 20 GHz channel spacing. The Error Vector Magnitude (EVM) values of the generated waveforms were approximately 16.4%. The OAWG module can rapidly and arbitrarily reconfigure waveforms upon every pulse arriving at 2 ns repetition time. The result of this work indicates the feasibility of truly dynamic optical arbitrary waveform generation where the reconfiguration rate or the modulator bandwidth must exceed the channel spacing of the AWG and the optical frequency comb.


Optics Express | 2017

Uniform emission, constant wavevector silicon grating surface emitter for beam steering with ultra-sharp instantaneous field-of-view

Kuanping Shang; Chuan Qin; Yu Zhang; Guangyao Liu; Xian Xiao; Shaoqi Feng; S. J. B. Yoo

We report on uniform emission intensity profile, uniform propagation constant silicon gratings for beam steering application with ultra-sharp instantaneous field-of-view (IFOV). To achieve uniform emission intensity across relatively long emission length, we designed a custom grating with varying Si3N4 width and duty cycle while maintaining a uniform propagation constant for relatively narrow divergence emission pattern. We designed and fabricated the custom Si3N4/Si grating with the varying Si3N4 width/duty cycle together with the reference Si3N4/Si grating with a constant 50:50 duty cycle. The custom grating demonstrated the beam steering angle value of 6.6° by sweeping wavelength between 1530 nm and 1575 nm with the emission length over 1 mm. The measured IFOV based on the 3-dB beamwidth values of the far field patterns for the TE polarization are 0.10° and 0.75° for the custom grating and for the reference grating, respectively. The custom grating also indicates mode-selective behavior due to the perturbation of propagation constant for input modes other than TE polarization. The measured TE-mode to TM-mode suppression ratio for the custom grating is approximately 8.2 dB peak-to-peak measured at far field.


Optics Express | 2017

Hybrid integration of modified uni-traveling carrier photodiodes on a multi-layer silicon nitride platform using total reflection mirrors

Yang Shen; Shaoqi Feng; Xiaojun Xie; Jizhao Zang; Siwei Li; Tiehui Su; Kuanping Shang; Weicheng Lai; Guangyao Liu; S. J. Ben Yoo; Joe C. Campbell

We demonstrate hybrid integration of modified uni-traveling carrier photodiodes on a multi-layer silicon nitride platform using total reflection mirrors etched by focused ion beam. The hybrid photodetectors show external responsivity of 0.15 A/W and bandwidth of 3.5 GHz for devices with a diameter of 80 µm. The insertion loss of the waveguide is 3 dB and the coupling efficiency of the total reflection mirror is -3 dB. The highest RF output power is -0.5 dBm measured at 3 GHz with 9 mA photocurrent and -9 V bias.


conference on lasers and electro optics | 2017

Photonic integrated circuit-based imaging system for SPIDER

Katherine E Badham; Richard L. Kendrick; Danielle Wuchenich; Chad Ogden; Guy Chriqui; Alan Duncan; Samuel T. Thurman; S. J. B. Yoo; Tiehui Su; Weicheng Lai; Jaeyi Chun; Siwei Li; Guangyao Liu

The Lockheed Martin Advanced Technology Center and the University of California at Davis (UC Davis) has developed an interferometric imaging system based on photonic integrated circuits (PICs). This approach could enable a new hardware architecture with a 10x to 100x reduction in size and weight compared to traditional imaging systems, particularly targeted for space applications. The current PIC design consists of a three-layer system of waveguides, arrayed waveguide gratings (AWGs) and multi-mode interferometers (MMIs) that link 12 interferometric baselines to measure the phase and amplitude of the mutual intensity of an extended object. A series of lenslets couple light into 24 input waveguides on one edge of the PIC. On the opposite side there are 206 interferometer output ports that provide the fringe data for creating images. In this paper we will describe the photonic integrated circuit design and the testbed used to create the first images of extended scenes. We will also summarize the image reconstruction steps and present the final images.


Optics Express | 2017

Silicon nitride tri-layer vertical Y-junction and 3D couplers with arbitrary splitting ratio for photonic integrated circuits

Kuanping Shang; Shibnath Pathak; Guangyao Liu; Shaoqi Feng; Siwei Li; Weicheng Lai; S. J. B. Yoo

We designed and demonstrated a tri-layer Si3N4/SiO2 photonic integrated circuit capable of vertical interlayer coupling with arbitrary splitting ratios. Based on this multilayer photonic integrated circuit platform with each layer thicknesses of 150 nm, 50 nm, and 150 nm, we designed and simulated the vertical Y-junctions and 3D couplers with arbitrary power splitting ratios between 1:10 and 10:1 and with negligible(< -50 dB) reflection. Based on the design, we fabricated and demonstrated tri-layer vertical Y-junctions with the splitting ratios of 1:1 and 3:2 with excess optical losses of 0.230 dB. Further, we fabricated and demonstrated the 1 × 3 3D couplers with the splitting ratio of 1:1:4 for symmetric structures and variable splitting ratio for asymmetric structures.


optical fiber communication conference | 2015

Ultra-low loss vertical optical couplers for 3D photonic integrated circuits

Kuanping Shang; Shibnath Pathak; Guangyao Liu; S. J. B. Yoo


Optica | 2018

Low-loss prism-waveguide optical coupling for ultrahigh-Q low-index monolithic resonators

Guangyao Liu; Vladimir S. Ilchenko; Tiehui Su; Yi-Chun Ling; Shaoqi Feng; Kuanping Shang; Yu Zhang; Wei Liang; Anatoliy A. Savchenkov; Andrey B. Matsko; Lute Maleki; S. J. Ben Yoo


conference on lasers and electro optics | 2015

Si 3 N 4 multilayer platform for photonic integrated circuits

Kuanping Shang; Shibnath Pathak; Binbin Guan; Guangyao Liu; Chuan Qin; Ryan P. Scott; S. J. B. Yoo


IEEE\/OSA Journal of Optical Communications and Networking | 2018

Experimental demonstration of a 64-port wavelength routing thin-CLOS system for data center switching architectures

Roberto Proietti; Xian Xiao; Kaiqi Zhang; Guangyao Liu; Hongbo Lu; P. Fotouhi; J. Messig; S. J. B. Yoo


optical fiber communication conference | 2016

Tri-layer, vertical Y-junction, Si3N4/SiO2 3D photonic integrated circuits with arbitrary splitting ratio

Kuanping Shang; Shibnath Pathak; Binbin Guan; Guangyao Liu; Shaoqi Feng; S. J. B. Yoo

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S. J. B. Yoo

University of California

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Kuanping Shang

University of California

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Shaoqi Feng

University of California

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Tiehui Su

University of California

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Siwei Li

University of California

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Weicheng Lai

University of California

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S. J. Ben Yoo

University of California

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Chuan Qin

University of California

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Hongbo Lu

University of California

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