Browsing by Author "Wun, Jhih-Min"

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106-fJ/(bit.km) 2-km OFDM OM4 MMF Transmissions for Energy Efficient Optical Interconnects
(2013)
Lu, I-Cheng
;
Chen, Hsing-Yu
;
Wei, Chia-Chien
;
Shi, Jin-Wei
;
Tsai, Sheng-Fan
Employing high-performance 850-nm VCSELs with oxide-relief and Zn-diffusion structures, we demonstrate 17.8-Gbps 2-km OM4 fiber transmissions. Meanwhile, ultra-low EDDR of 106 fJ/(bit km) with bias current as low as 1.9 mA is achieved.
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.
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
;
Chen, Yi-Han
;
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 In0.52Al0.48As Based Avalanche Photodiode With Top-Illuminated Design for 100 Gb/s ER-4 System
(2018-12-01)
Wu, Song-Lin
;
Naseem
;
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.
Optimization of mode numbers of VCSELs for small-cell backhaul applications
(2015-07-15)
Lu, I-Cheng
;
Wei, Chia-Chien
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Shi, Jin-Wei
;
Chen, Hsing-Yu
;
Tsai, Sheng-Fan
This paper reports optical orthogonal frequency-division multiplexing (OFDM) transmission using 850 nm Zn-diffusion Vertical-Cavity Surface-Emitting Lasers (VCSELs) and multimode fiber (MMF) for small-cell backhaul applications. We also investigated the influence of side mode suppression ratio (SMSR) on the performance of OFDM modulation. By further optimizing the Zn-diffusion conditions and oxide aperture size, a high-power (6.7 mW) SM (SMSR > 30 dB) VCSEL is demonstrated. By using OFDM modulation and bit-loading algorithm, record-high BRDP (91 Gb/s km) at 26 Gb/s transmission under FEC threshold (bit error rate (BER) < 3.8 x 10(-3)) across 3.5 km OM4 fiber has been successfully demonstrated. (C) 2015 Elsevier B.V. All rights reserved.
Oxide-Relief and Zn-Diffusion 850-nm Vertical-Cavity Surface-Emitting Lasers With Extremely Low Energy-to-Data-Rate Ratios for 40 Gbit/s Operations
(2013-03-01)
Shi, Jin-Wei
;
Yan, Jhih-Cheng
;
Wun, Jhih-Min
;
Chen, Jason
;
Yang, Ying-Jay
We demonstrate novel structures of a vertical-cavity surface-emitting laser (VCSEL) for high-speed (similar to 40 Gbit/s) operation with ultralow power consumption performance. Downscaling the size of oxide aperture of VCSELs is one of the most effective ways to reduce the power consumption during high-speed operation. However, such miniaturized oxide apertures (similar to 2 mu m diameter) in VCSELs will result in a large differential resistance, optical single-mode output, and a small maximum output power (< 1 mW). These characteristics seriously limit the maximum electrical-to-optical (E-O) bandwidth and device reliability. By the use of the oxide-relief and Zn-diffusion techniques in our demonstrated 850-nm VCSELs, we can not only release the burden imposed on downscaling the current-confined aperture for high speed with low-power consumption performance, but can also manipulate the number of optical modes inside the cavity to maximize the E-O bandwidth and product of bit-rate transmission distance in an OM4 fiber. State-of-the-art dynamic performances at both room temperature and 85 degrees C operations can be achieved by the use of our device. These include extremely high D-factors (similar to 13.5 GHz/mA(1/2)), as well as record-low energy-to-data ratios (EDR: 140 fJ/bit) at 34 Gbit/s operation, and error-free transmission over a 0.8-km OM4 multimode fiber with a record-low energy-to-data distance ratio (EDDR: 175.5 fJ/bit. km) at 25 Gbit/s.
Photonic chirped radio-frequency generator with ultra-fast sweeping rate and ultra-wide sweeping range
(2013-05-06)
Wun, Jhih-Min
;
Wei, Chia-Chien
;
Chen, Jyehong
;
Goh, Chee Seong
;
Set, S. Y.
A high-performance photonic sweeping-frequency (chirped) radio-frequency (RF) generator has been demonstrated. By use of a novel wavelength sweeping distributed-feedback (DFB) laser, which is operated based on the linewidth enhancement effect, a fixed wavelength narrow-linewidth DFB laser, and a wideband (dc to 50 GHz) photodiode module for the hetero-dyne beating RF signal generation, a very clear chirped RF waveform can be captured by a fast real-time scope. A very-high frequency sweeping rate (10.3 GHz/mu s) with an ultra-wide RF frequency sweeping range (similar to 40 GHz) have been demonstrated. The high-repeatability (similar to 97%) in sweeping frequency has been verified by analyzing tens of repetitive chirped waveforms. (C) 2013 Optical Society of America
Single-Mode, High-Speed, and High-Power Vertical-Cavity Surface-Emitting Lasers at 850 nm for Short to Medium Reach (2 km) Optical Interconnects
(2013-12-15)
Shi, Jin-Wei
;
Wei, Zhi-Rui
;
Chi, Kai-Lun
;
Jiang, Jia-Wei
;
Wun, Jhih-Min
The vertical-cavity surface-emitting lasers (VCSELs) with high single-mode (narrow linewidth) output power are essential to minimize chromatic dispersion and to further improve the bit-rate distance product in a multimode fiber, which has a significant propagation loss (similar to 3.5 dB/km) at 850 nm wavelength. Here, we demonstrate the detailed design considerations and fabrication of a single-mode, high-power, and high-speed VCSELs at the 850 nm wavelength with oxide-relief and Zn-diffusion apertures for the application of short (0.3 km) to medium reach (2 km) optical interconnects. By optimizing the relative geometric sizes between two such apertures in our demonstrated 850-nm VCSELs, we can not only attain high single-mode output power (similar to 6.5 mW), but also with a reasonable threshold current (< 2.0 mA). Furthermore, the spatial hole burning effect induced low-frequency roll off can also be minimized in our optimized structure to obtain a maximum data rate up to 26 Gbit/s. The record-high bit rate-distance products for OM4 MMF transmission under ON-OFF keying (14 Gbit/s x 2.0 km) modulation formats have been successfully demonstrated by the use of our VCSEL.
Strong Wavelength Detuning of 850 nm Vertical-Cavity Surface-Emitting Lasers for High-Speed (>40 Gbit/s) and Low-Energy Consumption Operation
(2015-11-01)
Chi, Kai-Lun
;
Yen, Jia-Liang
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Wun, Jhih-Min
;
Jiang, Jia-Wei
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Lu, I-Cheng
The strong (>20 nm) wavelength detuning technique has been demonstrated to enhance the modulation speed and high-temperature characteristics (at 85 degrees C), as well as lower the required driving current density performance of oxide-relief 850-nm vertical-cavity surface-emitting lasers (VCSELs) for >40 Gbit/s operation. By increasing the wavelength detuning from 15 to 20 nm, a significant improvement in the electrical-to-optical (E-O) bandwidth (20 to 27 GHz) of the VCSEL can be observed. This detuning design (similar to 20 nm) is incorporated along with a Zn-diffusion structure into our oxide-relief VCSEL with a miniaturized oxide-relief aperture (similar to 3 mu m). Highly single-mode, high-speed (26 GHz) operation, and moderate differential resistance (100 Omega) values can be simultaneously achieved. In addition, it is found that devices with a further larger detuning wavelength (>20 nm) and enlarged oxide-relief apertures (similar to 8 mu m) can sustain the same maximum E-O bandwidth (26 GHz) as that of a miniaturized (similar to 3 mu m) VCSEL, resulting in the lower driving current density (8 versus 18.8 kA/cm(2)) required for high-speed performance. Excellent transmission performance, which includes an extremely low energy-to-data rate ratio (EDR: 228 fJ/bit; over 100 m OM4 fiber) and record-low driving-current density (8 kA/cm(2); 3.5 mA) has been successfully achieved for 41 Gbit/s error-free transmission for these VCSELs.
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
;
Wun, Jhih-Min
;
Wu, Song-Lin
;
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.
Ultra Low Power VCSEL for 35-Gbps 500-m OM4 MMF Transmissions Employing FFE/DFE Equalization for Optical Interconnects
(2013)
Lu, I-Cheng
;
Shi, Jin-Wei
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Chen, Hsing-Yu
;
Wei, Chia-Chien
;
Tsai, Sheng-Fan
By use of optimized design 850-nm VCSELs under OOK modulation and FFE/ DFE equalization, high bit-rate distance product (35-Gbps 500-m and 25-Gbps 1000-m) through OM4 MMF transmissions with ultra-low power consumption are successfully achieved.