Browsing by Author "Ledentsov, N. N."

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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.