Analysis of Optical Erasure Efficiency in WDM-PONs Employing Carrier Remodulation

This paper proposes a method to monitor the operation performance of reflective semiconductor optical amplifier (RSOA)-based optical network units (ONUs) in wavelength-reuse wavelength-division-multiplexing passive optical network topologies. For this goal, the optical erasure efficiency of ONU RSOA is numerically evaluated through remote measurements at the optical line terminal site, using the VPI Transmission Maker software. The results show good correlation with the optical erasure behavior of RSOA in the injection power range of –20 to –5 dB, bias current of 50 and 150 mA, and confinement factor of 0.2 and 0.3. As a consequence, this method can be used to qualitatively estimate the optical and electrical features of ONU RSOA from the central office, instead of performing a local direct measurement.     

Noise reduction of tunable laser based on mutual injection-locked reflective semiconductor optical amplifiers

A tunable laser source based on mutual injection-locked reflective semiconductor optical amplifiers (MIL-RSOAs) using a tunable bandpass filter was investigated to reduce relative-intensity noise (RIN) and improve the carrier-to-noise ratio (CNR) without additional optoelectronic compensation. Compared with laser based on self-injection-locked RSOAs (SIL-RSOAs), the laser based on MIL-RSOAs reduced RIN by as much as 16 dB and improved CNR by as much as 20 dB. The proposed method improved sensitivity for 1.25 Gb/s transmission by >15 dB compared with using traditional laser based on SIL-RSOAs.     

Using Fabry-Perot laser diode and reflective semiconductor optical amplifier for long reach WDM-PON system

In this investigation, we propose and investigate the simple self-injection locked Fabry-Perot laser diodes (FP-LDs) in optical line terminal (OLT); and wavelength-tunable optical network unit (ONU) using reflective optical semiconductor amplifier (RSOA) and FP-LD laser for downstream and upstream traffic in long reach (LR) wavelength division multiplexed-passive optical network (WDM-PON) respectively. The output performance of the proposed two laser sources in terms of power and side-mode suppression ratio (SMSR) has been discussed. Here, for the downstream traffic, the proposed optical transmitter can be directly modulated at 2.5 Gb/s on-off keying (OOK) format with nearly 0.4 dB power penalty at bit error rate (BER) of 10⁻⁹ through 75 km single-mode fiber (SMF) transmission. Moreover, the proposed upstream transmitter can be directly modulated at 1.25 and 2.5 Gb/s with nearly 0.5 and 1.1 dB power penalty, respectively, at the BER of 10⁻⁹.     

A fiber-ring laser incorporating dual mode-locking mechanism

A fiber-ring laser incorporating dual mode-locking mechanisms is presented and demonstrated. A multi-quantum well (MQW) semiconductor optical amplifier (SOA) acts as active loss modulator, because the external optical signal injection results in gain depletion. In addition, a reflective SOA (RSOA) and a polarization beam splitter (PBS) introduce nonlinear polarization rotation (NPR), and also function as a saturable absorber. With this dual mode-locking mechanism, 10 GHz repetition-rate stable pulses, with pulse width of 16 ps and a root-mean-square timing jitter of 1 ps, was obtained without the use of external compression approaches.