Browsing by Author "Shih, Tien-Tsorng"

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Comparison of single-/few-/multi-mode 850 nm VCSELs for optical OFDM transmission
(2017-07-10)
Kao, Hsuan-Yun
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Tsai, Cheng-Ting
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Leong, Shan-Fong
;
Peng, Chun-Yen
;
Chi, Yu-Chieh
For high-speed optical OFDM transmission applications, a comprehensive comparison of the homemade multi-/few-/single-transverse mode (MM/FM/SM) vertical cavity surface emitting laser (VCSEL) chips is performed. With microwave probe, the direct encoding of pre-leveled 16-QAM OFDM data and transmission over 100-m-long OM4 multi-mode-fiber (MMF) are demonstrated for intra-datacenter applications. The MM VCSEL chip with the largest emission aperture of 11 mu m reveals the highest differential quantum efficiency which provides the highest optical power of 8.67 mW but exhibits the lowest encodable bandwidth of 21 GHz. In contrast, the SM VCSEL chip fabricated with the smallest emission aperture of only 3 mu m provides the highest 3-dB encoding bandwidth up to 23 GHz at a cost of slight heat accumulation. After optimization, with the trade-off set between the receiving signal-to-noise ratio (SNR) and bandwidth, the FM VCSEL chip guarantees the highest optical OFDM transmission bit rate of 96 Gbit/s under back-to-back case with its strongest throughput. Among three VCSEL chips, the SM VCSEL chip with nearly modal-dispersion free feature is treated as the best candidate for carrying the pre-leveled 16-QAM OFDM data over 100-m OM4-MMF with same material structure but exhibits different oxide-layer confined gain cross-sections with one another at 80-Gbit/s with the smallest receiving power penalty of 1.77 dB. (C) 2017 Optical Society of America
CWDM DFBLD Transmitter Module for 10-km Interdata Center With Single-Channel 50-Gbit/s PAM-4 and 62-Gbit/s QAM-OFDM
(2018-02-01)
Kao, Hsuan-Yun
;
Su, Zhe-Xian
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Shih, Hsiang-Shun
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Chi, Yu-Chieh
;
Tsai, Cheng-Ting
Single-channel 50-Gbit/s 4-level pulse amplitude modulation (PAM-4) and 62-Gbit/s orthogonal frequency division multiplexed quadrature amplitude modulation (QAM-OFDM) direct encoding of an uncooled coarse wavelength division multiplexer (CWDM) 100-Gbit/s distributed feedback laser diodes (DF-BLD) transmitter module at 1310-nm transmitter interdata center transmission over 10-km single-mode fiber (SMF) are demonstrated. To enable preleveled 16-QAM OFDM and PAM-4 data transmissions at 62 and 50 Gbit/s, the 1310-nm channel of the DFBLD CWDM transmitter provides modulation bandwidth of 15 GHz, side-mode suppression ratio of 48 dB, and relative intensity noise of -126 dBc/Hz. For encoding the PAM-4 data, the 1310nm channel of the CWDM DFBLD 100-Gbit/s transmitter achieves transmission capacities of 58 and 50 Gbit/s after BtB and 10-km SMF transmissions, respectively. Instead of supporting the back-to-back 16-QAM OFDM with the transmission at 62 Gbit/s with forward error correction (FEC) certified BER of 3.3x10(-3), such a CWDM 100-Gbit/s DFBLD transmitter module can still maintain its highest data rate capacity to indicate a receiving power penalty of 0.35 dB even after 10-km SMF propagation. This is mainly attributed to the selected channel wavelength of the narrow-linewidth DFBLD, which suffers from extremely low chromatic dispersion and RF fading effect.
Efficient Heat Dissipation of Uncooled 400-Gbps (16x25-Gbps) Optical Transceiver Employing Multimode VCSEL and PD Arrays
(2017-04-18)
Shih, Tien-Tsorng
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Chi, Yu-Chieh
;
Wang, Ruei-Nian
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Wu, Chao-Hsin
;
Huang, Jian-Jang
An effective heat dissipation of uncooled 400-Gbps (16x25-Gbps) form-factor pluggable (CDFP) optical transceiver module employing chip-on-board multimode 25-Gbps vertical-surface-emitting-laser (VCSEL) and 25-Gbps photodiode (PD) arrays mounted on a brass metal core embedded within a printed circuit board (PCB) is proposed and demonstrated. This new scheme of the hollow PCB filling with thermally-dissipated brass metal core was simulated and used for high temperature and long term stability operation of the proposed 400-Gbps CDFP transceiver. During one-hour testing, a red-shift of central wavelength by 0.4-nm corresponding temperature increment of 6.7 degrees C was observed with the brass core assisted cooler module. Such a temperature change was significantly lower than that of 28.3 degrees C for the optical transceiver driven with conventional circuit board. After 100-m distance transmission over a multimode fiber (OM4), the 400-Gbps CDFP transceiver exhibited dispersion penalty of 2.6-dB, power budget of >= 3-dB, link loss of <= 0.63-dB, mask margin of 20%, and bit error rate (BER) of <10(-12) with maintained stability more than one hour. The developed 400-Gbps CDFP transceiver module employing low-power consumption VCSEL and PD arrays, effective coupling lens arrays, and well thermal-dissipation brass metal core is suitable for use in the low-cost and high-performance data center applications.
Few-Mode 850-nm VCSEL Chip with Direct 16-QAM OFDM Encoding at 80-Gbit/s for 100-m OM4 MMF Link
(2017-01-01)
Kao, Hsuan-Yun
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Tsai, Cheng-Ting
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Pong, Chun-Yen
;
Liang, Shan-Fong
;
Weng, Zu-Kai
Chip-level direct 16-QAM OFDM encoding of a few-transverse-mode 850-nm Zn-diffused VCSEL is employed to transmit 80-Gbit/s data covering 20-GHz analog bandwidth over 100-m-long OM4 MMF with corresponding BER of 3.3x10(-3).
Few-mode VCSEL chip for 100-Gb/s transmission over 100 m multimode fiber
(2017-10-01)
Kao, Hsuan-Yun
;
Chi, Yu-Chieh
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Tsai, Cheng-Ting
;
Leong, Shan-Fong
;
Peng, Chun-Yen
A few-mode (FM) vertical cavity surface emitting laser (VCSEL) chip with heavily zinc-diffused contact layer and oxide-confined cross-section is demonstrated for carrying pre-leveled 16-quadrature amplitude modulation orthogonal frequency division multiplexing (QAM-OFDM) data in OM4 multi-mode fiber (MMF) over 100 m for intra-data-center applications. The FM VCSEL chip, which has an oxide-confined emission aperture of 5 mu m, demonstrates high external quantum efficiency, provides an optical power of 2.2 mW at 38 times threshold condition, and exhibits 3 dB direct-modulation bandwidth beyond 22 GHz at a cost of slight heat accumulation. At a DC bias point of 5 mA (22.6I(th)) the FM VCSEL chip, with sufficiently normalized modulation output, supports Baud and data rates of 25 and 100 Gb/s, respectively, with forward error correction (FEC) certifying receiving quality after back-to-back transmission. After passing through 100 m OM4 MMF with a receiving power penalty of 4 dB, the FM VCSEL chip demonstrates FEC-certified transmission of the pre-leveled 16-QAM OFDM data at 92 Gb/s. (C) 2017 Chinese Laser Press
High-Temperature Insensitivity of 50-Gb/s 16-QAM-DMT Transmission by Using the Temperature-Compensated Vertical-Cavity Surface-Emitting Lasers
(2018-08-15)
Peng, Chun-Yen
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Tsai, Cheng-Ting
;
Wang, Huai-Yung
;
Wu, Yun-Chen
;
Shih, Tien-Tsorng
In this study, a 50-Gb/s 16-quadrature amplitude modulation discrete multitone (16-QAM-DMT) was applied to an 850-nm oxide-confined vertical-cavity surface-emitting laser (VCSEL) at various temperature ranging from 25 degrees C to 85 degrees C. This study reports the highest bit rate for directly modulated VCSELs operating at 85 degrees C, in addition to demonstrating, for the first time, 16-QAM-DMT with less dependence on slope efficiency (SE) reduction. By using a temperature-compensated VCSEL, this study determined the degradation of the bit error rate (BER) in terms of the signal-to-noise ratio. The analysis results demonstrate that the transmission quality is dominated by optical bandwidth rather than the SE. Therefore, the preleveling technique was applied for error rate recovery to reduce the BER from 6.3 x 10(-3) to 3.8 X 10(-3) with a 0.2-dB/GHz preleveling slope. Thus, a low-bandwidth system (nearly 10 GHz) was realized for high data-rate transmissions (50 Gb/s) at 85 degrees C. The 16-QAM-DMT transmission provides an effective approach to alleviating thermal problems that occur in high-speed optical communication without the requirement of any external amplification circuits.
Impedance Matched GaN LD Package for Direct OFDM Communication at 14 Gbps
(2016)
Huang, Yu-Fang
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Wu, Tsai-Chen
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Chi, Yu-Chieh
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Tsai, Cheng-Ting
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Wang, Wei
A transmission line aided impedance matching package for 450-nm GaN laser diode is employed to increase the directly encoded 16-QAM OFDM transmission up to 14-Gbps over 7 m in free-space after modulation throughput intensity optimization.
Modal Linewidth Dependent Transmission Performance of 850-nm VCSELs With Encoding PAM-4 Over 100-m MMF
(2017-10-01)
Kao, Hsuan-Yun
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Chi, Yu-Chieh
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Peng, Chun-Yen
;
Leong, Shan-Fong
;
Chang, Chun-Kai
By changing the transverse-mode spectral linewidth of vertical cavity surface emitting lasers (VCSELs) at 850 nm, the directly encoded four-level pulse amplitude modulation data transmission performance over 100-m-long OM4 multimode fiber (MMF) are demonstrated and compared. The multi-mode VCSEL chip with the largest aperture of 11 mu m reveals the widest spectral linewidth and the highest optical power, but provides the smallest modulation bandwidth to support only 44-and 28-Gb/s data rates for back-to-back (BtB) and 100-m OM4 MMF transmission cases, respectively. By shrinking the aperture size to reduce transverse-mode number, the few-mode VCSEL with the strongest throughput power enables a BtB transmission capacity as high as 52 Gb/s. However, its modal dispersion induced after OM4 MMF transmission inevitably degrade the data rate to 32 Gb/s. In contrast, the single-mode VCSEL with the smallest aperture of 3 mu m reveals the highest modulation bandwidth and negligible modal dispersion to show competitive BtB transmission capacity with that of the few-mode VCSEL. In particular, the single-mode VCSEL successfully achieves a data rate of 34 Gb/s with a power penalty as low as 1.4 dB, after 100-m OM4 MMF transmission.
Pre-leveled 16-QAM OFDM Modulation of an 850-nm VCSEL for 56-Gbit/s Transmission
(2016)
Tsai, Cheng-Ting
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Pong, Chun-Yen
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Wu, Yun-Chen
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Leong, Shan-Fong
;
Chi, Yu-Chieh
An 850-nm VCSEL carried 16-QAM OFDM transmission at 56 Gbit/s is demonstrated by using the pre-leveling technology, which reveals an optimized signal-to-noise ratio, error vector magnitude and bit-error-rate of 16. 4 dB, 15.1 % and 1.2 x10(-3), respectively.
RIN Suppressed Multimode 850-nm VCSEL for 56-Gbps 16-QAM OFDM and 22-Gbps PAM-4 Transmission
(2016)
Tsai, Cheng-Ting
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Chang, Shuo
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Pong, Chun-Yen
;
Liang, Shan-Fong
;
Chi, Yu-Chieh
A multimode 850-nm VCSEL with its relative-intensive-noise suppressed to -145 dBc/Hz is employed for directly encoded 56-Gbps 16-QAM OFDM and 22-Gbps PAM-4 transmissions with corresponding BERs of 3.2x10(-3) and 1.9x10(-10), respectively.