Guang Yong Chu

Exploiting RSOA for Uplink Transmission with Coherent Detection for Low Cost UDWDM-PON

Upstream phase modulation exploiting low cost reflective semiconductor optical amplifier (RSOA) at ONU is applied for simplified coherent detection through DFBs as local lasers at ONU and at OLT.

Monolithically Integrated Dual-Output DEML for Full Duplex DPSK-ASK and DPSK-SSB ONU in Ultra-Dense Channel Spaced Access Network

Ultra-dense access network attracts peoples attention recently; however, until now it is difficult to implement it commercially owing to cost, footprint, and the traditional complexity of coherent receiver. Single laser, especially integrated laser-based optical network unit (ONU) provides a potential system for simplifying the ONU. Here, we show a 2.5-Gb/s/user bidirectional transmission with 5-GHz channel spacing between uplink and downlink for ultra-dense wavelength division multiplexed. A monolithic integration on dual output dual electro-absorption modulated laser (DEML)-based ONU for “λ-to-the-user” network is demonstrated. Furthermore, bidirectional differential phase-shift keying (DPSK)-amplitude shift keying and DPSK-single side band transmission with low-footprint, monolithically integrated DEML at ONU are also tested.

Ultrafast Wavelength Jumping and Wavelength Adjustment With Low Current Using Monolithically Integrated FML for Long-Reach UDWDM-PON

Ultrafast wavelength jumping at optical network units (ONUs) for an access network with frequency modulated lasers (FMLs) is demonstrated. This FML consists of an intracavity tunable phase section and filtering gain section. It provides a total of 4.2 nm tuning range with fast wavelength jumping (2.2 nm in 1 μs) and fast adjustment (1.3 nm in 1.8 ns), providing a candidate for the fast tuning ONU for coherent ultradense wavelength-division multiplexing passive optical networks (WDM-PONs).

Optimizing reflective semiconductor optical amplifier as phase modulator for low cost colorless ONU with 3x3 homodyne detection

Overcome the limited modulation bandwidth of low cost uncooled To-can packaged RSOA (∼400 MHz) and operate it at 3.125 Gb/s using homodyne techniques with the optimal performance for phase modulation via measured characteristics.

Ultra-dense WDM access network field trial

An UDWDM-PON with simple real-time ASK and DPSK transceivers at 6.25 GHZ channel spacing is validated in a field-trial with deployed fiber with power budget above 40 dB. This work presents final results of the Coconut European Project.

Coherent ONU based on 850 μm-long cavity-RSOA for next-generation ultra-dense access network

In this Letter, an efficient bidirectional differential phase-shift keying (DPSK)-DPSK transmission for a ultradense wavelength division-multiplexed passive optical network is proposed. A single distributed feedback laser at the optical network unit (ONU) is used both as the local laser for downlink coherent detection and the optical carrier for uplink. Phase-shift keying is generated using a low-cost reflective semiconductor optical amplifier (RSOA) at the ONU. The RSOA chip has the bandwidth of 4.7 GHz at the maximum input power and bias current. For uplink transmission, the sensitivity of the RSOA chip reaches -48.2 dBm at the level of bit error rate = 10(-3) for back-to-back, and the penalty for 50 km transmission is less than 1 dB when using polarization diversity.

Field-trial of a λ-to-the-user high-budget PON using a novel class of low-cost coherent transceivers and compatible with EPON system operation

COCONUT project demonstrated an innovative DWDM Passive Optical Network implementing the full λ-to-the-user concept in a filterless distribution fiber network. We make use of an innovative class of coherent transceivers that exploit the advantages of coherent detection in terms of sensitivity and channel selectivity in a cost efficient manner. The different transceivers developed target different use case scenarios, showing perfect compatibility with legacy infrastructures installed. In this paper, we report the successful trial of the proposed system in a testbed where 4 different coherent transceivers (plus one legacy E-PON system) ran simultaneously, operating over 14 DWDM channels, in a dark-fiber network in the city of Pisa, delivering real-time and/or test traffic. The testbed demonstrated filterless operations, multi-rate transmission (from 1.25 to 10 Gb/s/λ), high ODN loss (18 – 40 dB) as well as a bi-directional channel monitoring system.

Performance comparison between direct phase modulated DFB and RSOA for cost effective transmitter in udWDM-PONs

The performance of a directly phase modulated RSOA and an equalized DFB is compared with homodyne coherent detection for udWDM-PONs. Both device produce similar signals but the receiver sensitivity improves by 1.5dB at BER=10-3 with the RSOA because of its flatter phase response and less intensity modulation residual than the DFB.