Browsing by Author "Chao, Rui-Lin"

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BJT-Type Optical Phase Shifter With Small Power Consumption and Fast Response Time on a Silicon Photonics Foundry Platform
(2020-03-01)
Chao, Rui-Lin
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Ahmad, Zohauddin
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Chen, Jason
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Lai, Yinchieh
;
Shi, Jin-Wei
We demonstrate a novel optical phase shifter with a bipolar junction transistor (BJT) type of device structure based on the silicon photonics foundry platform. By operating such a device in saturation mode, we obtain measured output I-EC-V-EC characteristics very similar to those of an ideal diode, which has a nearly zero turn-on voltage and an extremely small differential resistance. The huge amount of injected current under a small voltage swing (0.1 V) in the operation window makes it possible to obtain significant plasma induced change of the refractive index in the optical waveguide with an extremely small driving-voltage. The device has a small foot-print (500 mu m in length), but exhibits small static power consumption for the pi phase-shift (P-pi: 4.1 mW), reasonable propagation loss (0.02 dB/mu m), small driving-voltage (V-pi: 0.12 V), fast switching time (rise/fall <1.6/1 ns), a residue amplitude modulation (RAM) as small as 0.18 dB, and a very-low power consumption (0.45 mW) during dynamic operation.
Design and Analysis of Waveguide-Coupled Photonic THz Transmitters With an Extremely Wide Fractional Bandwidth
(2018-10-01)
Chen, Nan-Wei
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Wun, Jhih-Min
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Wang, Hao-Chen
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Chao, Rui-Lin
;
Koh, Christopher
The design and analysis of novel waveguide-coupled photonic transmitters, which can have an extremely wide +/- 3-dB fractional optical-to-electrical (O-E) bandwidth at near the tera-hertz (THz) operating frequency regime (100%; 0.1-0.3 THz), are presented. This novel module is composed of a customized WR-10-based wideband antenna and an ultrafast/high-power photodiode with a 0.33-THz 3-dB O-E bandwidth, which is flip-chip bonded onto an aluminum nitride substrate, integrated with an impedance matching circuit as well as a bow-tie radiator to serve as the antenna feed. The WR-10-based dual-ridge horn structure is adopted to realize the extremely wideband antenna because the dominant TEM mode supported by the dual ridges has no cutoff frequency. The proposed antenna exhibits more than 18 dB gain across the whole operating bandwidth (0.1-0.3 THz). With the transmitter operating at an output photocurrent of 10 mA and employing the same dual ridge-horn antenna at the receiving end, we can detect a reasonable power (31.6 mu W) at 0.24 THz through 1 cm wireless transmission.
Enhancement in speed and responsivity of uni-traveling carrier photodiodes with GaAs0.5Sb0.5/In0.53Ga0.47As type-II hybrid absorbers
(2019-05-27)
Naseem
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Ahmad, Zohauddin
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Chao, Rui-Lin
;
Chang, Hsiang-Szu
;
Ni, C-J
We demonstrate a top-illuminated high-speed uni-traveling carrier photodiode (UTC-PD) with a novel design in the p-type absorber, which call effectively shorten the photon absorption depth at telecommunication wavelengths (1.31 similar to 1.55 mu m) and further enhance the bandwidth-efficiency product of UTC-PD. In our proposed new UTC-PD structure, the p-type In0.53Ga0.47As absorption layer is replaced by the type-II GaAs0.5Sb0.5 (p)/In0.53Ga0.47As (i) hybrid absorber. Due to the narrowing of the bandgap and enhancement of the photo-absorption process at the type-II interface between the GaAs0.5Sb0.5 and In0.53Ga0.47As layers, our device shows an over 16.7% improvement in the responsivity compared with that of UTC-PD with the same thickness of pure In0.53Ga0.47As absorber (0.7 mu m) and a zero optical coupling loss. Our demonstrated device with a simple top-illuminated structure offers a large active mesa (25 mu m). a wide optical-to-electrical (O-E) bandwidth (33 GHz), a high responsivity (0.7 A/W), and a high saturation current (>5 mA) under 1.31 mu m optical wavelength. These promising results suggest that our proposed PD structure can fundamentally overcome the trade-off among bandwidth. efficiency. and device active diameter of high-speed PDs. (C) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Fully Integrated Photonic Microwave Tracking Generator on Heterogeneous III-V/Si Platform
(2017-01-01)
Chao, Rui-Lin
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Liang, Linjun
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Shi, Jin-Wei
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Hulme, Jared
;
Kennedy, M. J.
Fully-integrated photonic microwave tracking generators are demonstrated for the first time. By sweeping the wavelength separation among two-locked DFBs and one tunable laser, a two-tone photo-generated RF signal with tunable difference in frequency can be generated. 2017 Optical Society of America
Fully Integrated Photonic Millimeter-Wave Tracking Generators on the Heterogeneous III-V/Si Platform
(2018-05-15)
Chao, Rui-Lin
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Liang, Linjun
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Shi, Jin-Wei
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Komljenovic, Tin
;
Hulme, Jared
Fully integrated photonic microwave/millimeterwave (MMW) tracking generators, which include wavelength-tunable lasers, distributed feedback lasers, phase modulators, and high-speed photodiodes (PDs), are demonstrated on the heterogeneous integrated III-V-on-Si photonic platform. Two on-chip lasers are locked by an external optical phase-locked loop (OPLL), and the two-tone radio-frequency (RF) signals from the on-chip fast PDs can be photonically generated through the heterodyne-beating process between the wavelengthtunable laser and the OPLL output. Furthermore, the frequency spacing between such two-tone RF signals can be tracked by the oscillation frequency in the OPLL with a wide tunability (near dc to 10 GHz). Fast and truly continuous scanning of photo-generated MMW signals thus becomes feasible by simultaneously tuning the OPLL and the central wavelength of the tunable laser in the demonstrated photonic integrated circuit.
Heterogeneously Integrated InP Based 14,vanescentlyCoupled High-Speed and High-Power p-i-n Photodiodes on Silicon-on-Insulator (SOI) Substrate
(2016)
Hulme, Jared
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Kennedy, M. J.
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Chao, Rui-Lin
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Komljenovic, Tin
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Shi, Jin-Wei
we demonstrate InP based evanescently-coupled pi-n photodiodes heterogeneously integrated onto silicon-on insulator substrate. Using advanced waveguide structures and fabrication processes, it simultaneously achieves 67 GHz O-E bandwidth (RC-free), broad optical window (1520-1600nm) with 0.5 A/W internal responsivity, and high saturation currents (9 mA at 70 GHz).
High-brightness and high-speed vertical cavity surface-emitting laser arrays
(2020-04-20)
Khan, Zuhaib
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Shih, Jie-Chen
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Chao, Rui-Lin
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Tsai, Tzong-Liang
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Wang, Hsin-Chuan
High-power vertical-cavity surface-emitting laser (VCSEL) arrays, which can serve as the light source in modem lidar and three-dimensional optical sensing systems, have recently attracted a lot of attention. In these types of systems, the time-of-flight (ToF) technique, based on the round-trip time of short optical pulses is usually adopted. Further enhancement of the ranging distance and depth resolution in these ToF driven systems by the incorporation of a VCSEL array with a high available power, high brightness (narrow divergence angle), and fast response time is highly deskable. However, a large number of light emission apertures (several hundreds) in the VCSEL array is usually necessary to raise the output power level to several watts. This leads to a large parasitic capacitance and the RC-limited bandwidth may become the dominant limiting factor of the speed of the high-power VCSEL array. In this work, Zn-diffusion and oxide-relief apertures are used to manipulate the optical modes and reduce the parasitic capacitance, respectively, in a unit device for a 940 nm VCSEL array. The demonstrated VCSEL array has a quasi-single-mode output, high available power (4 W; 1% duty cycle), narrow divergence angle (similar to 14 degrees at 1/e(2)) under maximum output power, and a fast rise time (<100 ps). These results open up new possibilities for further enhancing the performance of ToF sensing systems at the 940 nm wavelength. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
High-Speed and High-Power GaSb Based Photodiode for 2.5 mu m Wavelength Operations
(2016-01-01)
Chao, Rui-Lin
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Wun, Jhih-Min
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Wang, Yu-Wen
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Chen, Yi-Han
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Bowers, J. E.
By using partially depleted Ga0.8In0.2As0.16Sb0.84 absorber in GaSb based photodiodes for 2.5 mu m wave length operation, such device achieves high-speed and high-saturation current (3.6 mA/6 GHz) performances with low dark current (0.7 mu A at -2V). Device modeling results suggest that the internal carrier response time limits its dynamic performance.
High-Speed Avalanche Photodiodes With Wide Dynamic Range Performance
(2019-12-01)
Zhao, Hao-Yi
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Naseem
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Jones, Andrew H.
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Chao, Rui-Lin
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Ahmad, Zohauddin
In this work, we demonstrate a novel top-illuminated avalanche photodiode (APD) with high-speed and wide dynamic range performance for coherent lidar applications, which needs simultaneous processing of weak light reflections from the object and a strong optical local-oscillator (LO) signal at the receiving end. By taking advantage of a partially depleted p-type In0.53Ga0.47As absorbing layer and a thin In0.52Al0.48 As multiplication layer (88 nm), the demonstrated APDs exhibit a wide optical-to-electrical bandwidth (16 GHz) and high responsivity (2.5 A/W at 0.9 V-br) near the saturation output current which is as high as >8 mA. Furthermore, the measured low excess noise (k = 0.14) characteristics of this device ensure its wide dynamic range performance. In addition, it should be noted that the measured nonlinear behaviors of these APDs are quite different from those of typical fast p-i-n photodiodes (PDs), which always show serious degradation in their O-E bandwidths at their saturation output. On the other hand, the measured bias dependent 3-dB O-E bandwidth of the demonstrated APDs can be pinned at 16 GHz without any degradation at around the saturation current output. Such distinct nonlinear APD behaviors can be attributed to the space-charge-screening effect induced gain reduction under high-power operation.
High-Speed Electro-Absorption Modulated Laser at 1.3 mu m Wavelength Based on Selective Area Growth Technique
(2019-01-01)
Ahmad, Zohauddin
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Chao, Rui-Lin
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Hung, Yung-Jr
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Chen, Jyehong
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Wei, Chia-Chien
We demonstrate InxAlyGa1-x-yAs based electro-absorption modulated DFB laser at 1.3 mu m wavelength based on selective area growth technique. The fabricated device exhibits 5 mW output power, wide E-O bandwidth (>40 GHz), 2V driving-voltage for 10 dB extinction ratio, and clear eye-opening at 32Gbit/sec.
High-Speed In0.52Al0.48As Based Avalanche Photodiode With Top-Illuminated Design for 100 Gb/s ER-4 System
(2018-12-01)
Wu, Song-Lin
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Naseem
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Wun, Jhih-Min
;
Chao, Rui-Lin
;
Huang, Jack Jia-Sheng
High-speed top-illuminated avalanche photodiodes (APDs) with large diameters (25 mu m) are demonstrated for the application of 4-channels 100 Gb/s data rate. They achieve a bandwidth of 17 GHz at low-gain (M-G = 6.2; 3.6 A/W) and large-gain bandwidth (responsivity bandwidth) product (410 GHz (237.8 GHz-A/W); 55% external efficiency at the unit gain) while maintaining invariant high speed (14 GHz) under high power (0.5 mW) and 0.9 V-b(r) operations. By packaging the demonstrated APD with a 25 Gb/s transimpedance amplifier in a 100 Gb/s ROSA package, a good sensitivity of around -20.6 dBm optical modulation amplitude (OMA) at the data rate of 25.78 Gb/s has been successfully demonstrated. The achieved sensitivity not only meets the required receiver sensitivity (-18.5 dBm OMA) in 100 GbE-ER-4 Lite (40 km) system, it is also comparable with that of the high-performance 1(N) Gb/s ROSA incorporated with the backside illuminated APD design. Overall, our novel APD structure can eliminate the costly flip-chip bonding package in the 100 Gb/s ROSA without sacrificing its sensitivity performance.
PNP-Type Optical Phase-Shifter with Low Power Consumption and Fast Switching Time on Silicon Photonics Foundry Platform
(2019-01-01)
Chao, Rui-Lin
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Ahmad, Zohauddin
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Chen, Jyehong
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Shi, Jin-Wei
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光電工程學系
We demonstrate a novel PNP bipolar junction transistor based optical phase-shifter on Si-photonic foundry platform. It exhibits a small static power consumption for pi phase-shift (P-pi: 3mW), small driving-voltages (V-pi:0.1 V), fast switching time (rise/fall <1.19/0.6ns), and very-low power consumption (0.7mW) during dynamic operations.
Top-Illuminated In0.52Al0.48As-Based Avalanche Photodiode With Dual Charge Layers for High-Speed and Low Dark Current Performances
(2018-03-01)
Chen, Yi-Han
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Wun, Jhih-Min
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Wu, Song-Lin
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Chao, Rui-Lin
;
Huang, Jack Jia-Sheng
A novel type of top-illuminated, etch-mesa In0.52Al0.48 As-based avalanche photodiode (APD) with high-speed (>25 Gb/s), low dark current performance has been demonstrated. The 25G APD device is composed of n-side down design with the In0.52Al0.48As multiplication (M) layer buried at the bottom to avoid the issues of surface breakdown and complex guard ring structure. In addition, we demonstrate that the new structure with two charge layers and triple mesas can effectively confine the electric-field within the center of M-layer and minimize the edge breakdown around the periphery of mesa. In contrast to the costly flip-chip bonding package with backside illumination, our demonstrated device is based on a simple top-illuminated structure that includes a large active diameter of 30 mu m for easy optical alignment, a reasonable punch-through responsivity (0.7 A/W at 1.31 mu m wavelength), and a good 3-dB optical-to-electrical (O-E) bandwidth (22.5 GHz) under low gain operations (M-G = similar to 3). Furthermore, it can sustain the 3-dB bandwidth of 15 GHz over a wide range of launched optical power (-17 to + 4.6 dBm) under a moderate gain (M-G = similar to 5) operation at 1.31 mu m wavelength. High-sensitivity (-16 dBm) for error-free 28 Gb/s operation can also be achieved at 1.55 mu m wavelength.
Type-II GaAs0.5Sb0.5/InP Uni-Traveling Carrier Photodiodes With Sub-Terahertz Bandwidth and High-Power Performance Under Zero-Bias Operation
(2017-02-15)
Wun, Jhih-Min
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Chao, Rui-Lin
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Wang, Yu-Wen
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Chen, Yi-Han
;
Shi, Jin-Wei
We successfully demonstrate ultrafast uni-traveling carrier photodiodes (PD) with sub-terahertz bandwidth (similar to 170 GHz) and high-power performance under zero bias and at 1.55-mu m optical wavelength operation. By using a type-II (GaAs0.5Sb0.5/InP) absorption-collector interface and inserting an n-type (1 x 1018 cm(-3)) charge layer in the collector, the current blocking (Kirk) effect can be greatly minimized. A stack of undoped Al-x In0.52Ga0.48-x As layers with different Aluminum mole fractions (x: 0.2 to 0.08) and bandgaps is adopted as the collector layer. This graded-bandgap design can provide a built-in electric field and further shorten the internal collector transit time. The demonstrated PD structure achieves a 3-dB optical-to-electrical bandwidth of 170 GHz and subterahertz output power -11.3 dBm at 170 GHz, a record among all the reported zero-bias PDs.