Browsing by Author "Yang, Ying-Jay"

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850 nm Zn-diffusion Vertical-Cavity Surface-Emitting Lasers with Oxide-Relief Structure for High-Speed and Energy-Efficient Optical Interconnects from Very-Short to Medium (2km) Reaches
(2015-01-01)
Shi, Jin-Wei
;
Wei, Chia-Chien
;
(Jyehong) Chen, Jason
;
Yang, Ying-Jay
;
光電工程學系
High-speed and "green" similar to 850 nm vertical-cavity surface-emitting lasers (VCSELs) have lately attracted lots of attention due to their suitability for applications in optical interconnects (OIs). To further enhance the speed and its maximum allowable linking distance of VCSELs are two major trends to meet the requirement of OI in next generation data centers. Recently, by use of the advanced 850 nm VCSEL technique, data rate as high as 64 Gbit/sec over 57m and 20 Gbit/sec over 2km MMF transmission have been demonstrated, respectively. Here, we will review our recent work about 850 nm Zn-diffusion VCSELs with oxide-relief apertures to further enhance the above-mentioned performances. By using Zn-diffusion, we can not only reduce the device resistance but also manipulate the number of optical modes to benefit transmission. Combing such device, which has excellent single-mode (SMSR> 30 dB) and high-power (similar to 7mW) performance, with advanced modulation format (OFDM), record-high bit-rate-distance-product through MMF (2.3 kmx28 Gbit/sec) has been demonstrated. Furthermore, by selective etching away the oxide aperture inside Zn-diffusion VCSEL, significant enhancement of device speed, D-factor, and reliability can be observed. With such unique VCSEL structure, > 40 Gbit/sec energy-efficient transmission over 100m MMF under extremely low-driving current density (< 10kA/cm(2)) has been successfully demonstrated.
850-nm VCSELs With p-Type delta-Doping in the Active Layers for Improved High-Speed and High-Temperature Performance
(2016-11)
Chi, Kai-Lun
;
Hsieh, Dan-Hua
;
Yen, Jia-Liang
;
Chen, Xin-Nan
;
Chen, Jason (Jyehong)
In this paper, we study the influence of p-type modulation doping on the dynamic/static performance of highspeed 850-nm VCSELs with highly strained multiple quantum wells. The studied device structure has a 3/2 lambda asymmetric cavity design, which can let the internal transit time of injected carriers be as short as that of 1/2 lambda cavity design and further improve its performance in terms of speed and output power for high single-mode operation. Our proposed VCSEL structure with p-type doping shows superior modulation speed with an output power comparable with that of the un-doped reference device under room temperature operation. Furthermore, when the operating temperature reaches 85 degrees C, there is a significant improvement in both the modulation speed and maximum power of the p-doped structures. According to our simulation, this can be attributed to the change in the quasi-Fermi levels of the injected carriers after the addition of p-doping in the active layers, which minimizes the electron leakage under high-temperature operation.
Bipolar Cascade Superluminescent Diodes at the 1.04-mu m Wavelength Regime
(2009-03-01)
Guol, Shi-Hao
;
Wang, Jr-Hung
;
Wu, Yu-Huei
;
Lin, Wei
;
Yang, Ying-Jay
In this study, we investigate the performance of GaAs-based bipolar cascade superluminescent diodes with different cavity lengths. The device operates around the important bio-optical therapeutic 1.04-mu m wavelength window. The introduction of tunnel junctions tends to minimize the nonuniform carrier distribution between distinct multiple quantum-wells (QWs), which is a problem in conventional SLDs, whose electroluminescent spectra are governed by the center wavelength of QWs near the p-side. Our devices exhibit nice electrical characteristics of low leakage current and overcome the limitation of nonuniform carrier distribution, thereby presenting a promising prospect for the near infrared white-light sources.
Energy Efficient 850 nm Vertical-Cavity Surface-Emitting Lasers with Extremely Low Driving-Current Density for > 40 Gbit/sec Error-Free Transmissions from RT to 85 degrees C
(2015)
Chi, Kai-Lun
;
Jiang, Jia-Wei
;
Yen, Jia-Liang
;
Lu, I-Cheng
;
Kuo, H. -C.
850nm VCSELs with record-low driving-current-density (8kA/cm(2)) small resistance (6012), wide-bandwidth (26GHz), and small energy-to-data-rate ratio (228fJ/bit; 3.5mA) for >41Gbit/sec error-free transmission over 100 (2) meter OM4 fiber at room-temperature (85 degrees C) have been demonstrated. (C) 2014 Optical Society of America
Low operation voltage macromolecular composite memory assisted by graphene nanoflakes
(2013)
Lai, Ying-Chih
;
Wang, Di-Yan
;
Huang, I-Sheng
;
Chen, Yu-Ting
;
Hsu, Yung-Hsuan
The trend towards simple and low-cost processing is one of the most important for macromolecular memory development. Here, bistable memory devices using a solution-processable active material, a mixture of graphene nanoflakes (GNFs) and insulating poly(vinyl alcohol) (PVA), are investigated, which serve as the first example for the direct integration of as-prepared nanoscale graphene into macromolecular memory devices through a one-step low-temperature processing method. Bistable electrical switching behavior and nonvolatile rewritable memory effects are realized by using an indium-tin-oxide/GNF-PVA/silver (ITO/GNF-PVA/Ag) sandwich structure. The resulting device exhibits low operation voltages of +1.4 V (turn-on) and -1.3 V (turn-off), which is promising for memory cells with low power consumptions. The programmable ON- and OFF-states possess a retention time of over 10(4) s and endure up to 10(7) read pulses. The carrier transport in the OFF- and ON-states follows the typical trap-limited space charge limited current and Ohmic laws, respectively. The asymmetric electrical switch behavior is therefore attributed to conducting filaments formed in the PVA layer assisted by the charged GNFs that induce the transition of the conductivity. Our study provides a potential approach for integrating as-prepared graphene into macromolecular memory devices with excellent performances through a simple solution-process.
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.
Single-Mode 850 nm Vertical-Cavity Surface-Emitting Lasers with Zn-diffusion and Oxide-relief Apertures for > 50 Gbit/sec OOK and 4-PAM Transmission
(2017-01-01)
Shi, Jin-Wei
;
Wei, Chia-Chien
;
Chen, Jason (Jyehong)
;
Ledentsov, N. N.
;
Yang, Ying-Jay
Vertical-cavity surface-emitting lasers (VCSELs) has become the most important light source in the booming market of short-reach (< 300 meters) optical interconnect (OI). The next generation OI has been targeted at 56 Gbit/sec data rate per channel (CEI-56G) with the total data rate up to 400 Gbit/sec. However, the serious modal dispersion of multi-mode fiber (MMF), limited speed of VCSEL, and its high resistance (> 150 Omega) seriously limits the >50 Gbit/sec linking distance (< 10 m) by using only on-off keying (OOK) modulation scheme without any signal processing techniques. In contrast to OOK, 4-PAM modulation format is attractive for > 50 Gbit/sec transmission due to that it can save one-half of the required bandwidth. Nevertheless, a 4.7 dB optical power penalty and the linearity of transmitter would become issues in the 4-PAM linking performance. Besides, in the modern OI system, the optics transreceiver module must be packaged as close as possible with the integrated circuits (ICs). The heat generated from ICs will become an issue in speed of VSCEL. Here, we review our recent work about 850 nm VCSEL, which has unique Zn-diffusion/oxide-relief apertures and special p-doping active layer with strong wavelength detuning to further enhance its modulation speed and high-temperature (85 degrees C) performances. Single-mode (SM) devices with high-speed (similar to 26 GHz), reasonable resistance (similar to 70 Omega) and moderate output power (similar to 1.5 mW) can be achieved. Error-free 54 Gbit/sec OOK transmission through 1km MMF has been realized by using such SM device with signal processing techniques. Besides, the volterra nonlinear equalizer has been applied in our 4-PAM 64 Gbit/sec transmission through 2-km OM4 MMF, which significantly enhance the linearity of device and outperforms fed forward equalization (FFE) technique. Record high bit-rate distance product of 128 Gbps.km is confirmed for optical-interconnect applications.
Single-Mode 850-nm VCSELs for 54-Gb/s ON-OFF Keying Transmission Over 1-km Multi-Mode Fiber
(2016-06-15)
Chi, Kai-Lun
;
Shi, Yi-Xuan
;
Chen, Xin-Nan
;
Chen, Jason (Jyehong)
;
Yang, Ying-Jay
By combing Zn-diffusion and oxide-relief apertures with strong detuning (>20 nm) in our demonstrated short-cavity (lambda/2) 850-nm vertical-cavity surface-emitting lasers (VCSELs), wide electrical-to-optical bandwidth (29-24 GHz), low-differential resistance (similar to 100 Omega), and (quasi) single-mode (SM) with reasonable output power (similar to 1.4 mW) performances can be simultaneously achieved. Error-free ON-OFF keying transmission at 54-Gb/s data rate through 1-km OM4 multi-mode fiber can be achieved by using highly SM device with forward error correction and decision feedback equalization techniques. As compared with the reference device with a larger oxide-relief aperture and a multi-mode performance, the SM device exhibits lower bit-error rate (1x10(-5) versus 1x10(-2)) at 54 Gb/s. This result indicates that modal dispersion plays more important role in transmission than that of output power does. We benchmark these results to an industrial 50-Gb/s SM VCSEL. It shows a higher bit-error-rate value similar to 3.5x10(-3) versus similar to 1.4x10(-4) under the same received optical power.
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 Enhancements in Output Power and High-Speed Data Transmission Performances by Using Parallel Oxide-Relief/Zn-Diffusion 850 nm VCSELs
(2016)
Chi, Kai-Lun
;
Chen, Xin-Nan
;
Chen, Jye-Hong
;
Bowers, J. E.
;
Yang, Ying-Jay
By using parallel two high-speed VCSELs, double increase in maximum output power (4 vs. 8mW), negligible degradation in 3-dB electrical-to-optical bandwidth (similar to 25 GHz), and strong enhancement in 46 Gbit/sec data transmission through OM4 MMF is achieved compared with those of single reference.
Strong Enhancements in Static/Dynamic Performances of High-Speed 850 nm Vertical-Cavity Surface-Emitting Lasers with P-type delta-Doping in Highly Strained Active Layers
(2016)
Chi, Kai-Lun
;
Chen, Xin-Nan
;
Yen, Jia-Liang
;
Lin, Wei
;
Chiu, Shi-Wei
By using p-type modulation doping in the highly strained MQWs of high-speed 850 nm VCSELs, significant enhancements in speed, slope efficiency, and maximum power have been simultaneously achieved as compared to those of un-doped references
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
;
Wun, Jhih-Min
;
Jiang, Jia-Wei
;
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.