F. Y. Shih

WDM extended reach passive optical networks using OFDM-QAM

In order to reduce the cost for delivering future broadband services, network operators are inclined to simplify the network architectures by integrating the metro and access networks into a single system. Hence, extended reach passive optical networks (ER-PONs) have been proposed. ER-PON usually has four new features: high data rate in both upstream and downstream signals (>1 Gb/s); reach extension to >100 km; a high split ratio (>100); and using wavelength division multiplexing (WDM). In this work, we propose and demonstrate a highly spectral efficient ER-PON using 4 Gb/s OFDM-QAM for both upstream and downstream signals, while achieving a high split-ratio of 256. The ER-PON employs optical components optimized for GPON (bandwidth of approximately 1 GHz) and reaches 100 km without dispersion compensation. Numerical analysis using 16, 64 and 256-QAM OFDM are also performed to study the back-to-back receiver sensitivities and power penalties at different electrical driving ratios.

Signal Remodulation of OFDM-QAM for Long Reach Carrier Distributed Passive Optical Networks

The passive optical network (PON) using orthogonal frequency-division multiplexing (OFDM) is a subject of many research works recently. The OFDM signal is especially good for long reach (LR)-PON due to its high tolerance to chromatic dispersion and high spectral efficiency. We study, for the first time, the possibility of using OFDM for signal remodulation in LR-PONs. Three different colorless optical networking unit (ONU) architectures, electroabsorption modulator-based, reflective semiconductor optical amplifier-based and injection-locked Fabry-Perot laser diode-based ONUs, are tested and compared. Error-free operations are achieved in 100-km fiber transmission without dispersion compensation.

A self-protected colorless WDM-PON with 2.5 Gb/s upstream signal based on RSOA

In this investigation, we propose and demonstrate a colorless wavelength division multiplexed passive optical network (WDM-PON) at 2.5 Gb/s using reflective semiconductor optical amplifier (RSOA)-based optical networking units (ONUs); together with a self-protected architecture against fiber fault. In the optical line terminal (OLT), we use an array of self-seeding Fabry-Perot laser diodes (FP-LDs) to provide single-longitudinal-mode (SLM) continuous wave (CW) optical sources for the external injection to the RSOA-based ONUs. The self-survivable function for protecting the fiber fault in the distributed fibers and the proposed network performance are investigated and discussed.

Stabilized dual-wavelength erbium-doped dual-ring fiber laser

A stable dual-wavelength erbium-doped fiber (EDF) compound ring laser using a double-ring filter (DRF) is proposed and demonstrated experimentally. By using a ring filter incorporated within the ring cavity, the fiber laser can lase two wavelengths simultaneously. The dual-wavelength output exhibits a good performance having the optical side-mode suppression ratios (SMSRs) of 45.3 and 46.3 dB and output powers of -8.1 and -7.1 dBm, respectively. In addition, the optical output stabilities of the ring laser have been also discussed.

Rayleigh Backscattering Performance of OFDM-QAM in Carrier Distributed Passive Optical Networks

The passive optical network (PON) using an orthogonal frequency-division-multiplexing (OFDM) format is a subject of many research works recently. Due to the high spectral efficiency, low bandwidth optical components can be used in this OFDM-PON. We quantify, for the first time, the performance of the OFDM signal when subjected to the noise generated by the two components of the Rayleigh backscattering (RB): carrier generated RB (carrier-RB) and signal generated RB (signal-RB) that are present in the carrier-distributed PONs. An RB comparison between OFDM quadrature amplitude modulation and nonreturn-to-zero is preformed.

Using OOK Modulation for Symmetric 40-Gb/s Long-Reach Time-Sharing Passive Optical Networks

Due to the requirement of broad bandwidth for next-generation access networks, present passive optical networks (PONs) will be upgraded to 40 Gb/s or higher data rate PONs. Hence, we propose and experimentally demonstrate a simple and efficient scheme to achieve a symmetric 40-Gb/s long-reach (LR) time-division-multiplexed PON by using four wavelength-division-multiplexed 10-Gb/s external on-off keying format channels to serve as the optical transmitter for downstream and upstream traffic simultaneously. Moreover, the system performance of LR transmission and split ratio have also been analyzed and discussed without dispersion compensation.

Signal-Remodulated Wired/Wireless Access Using Reflective Semiconductor Optical Amplifier With Wireless Signal Broadcast

In this letter, we propose and demonstrate a signal- remodulated wired/wireless network using reflective semiconductor optical amplifier as a colorless modulator in the optical networking unit/remote antenna unit. Dark return-to-zero and binary phase-shift-keying signals are used for the downstream wired and wireless broadcast, respectively. The downstream signal will be remodulated to produce the upstream nonreturn-to-zero signal.

Using four wavelength-multiplexed self-seeding Fabry-Perot lasers for 10 Gbps upstream traffic in TDM-PON

In this paper, we propose and experimentally investigate a simple self-injection Fabry-Perot laser scheme on each optical network unit (ONU) for 10 Gbps TDM passive optical networks (PONs). Based on the proposed four wavelength-multiplexed 2.5 Gbps lasers, the 10 Gbps uplink traffic can be achieved at a cost-effective way. The network architecture and performance have also been analyzed and discussed.

A simple self-restored fiber Bragg grating (FBG)-based passive sensing ring network

In this investigation, we propose and experimentally investigate a simple self-restored fiber Bragg grating (FBG)-based sensor ring system. This proposed multi-ring passive sensing architecture does not require active components in the network. In this experiment, the network survivability and capacity for the multi-point sensor systems are also enhanced. Besides, the tunable laser source (TLS) is adopted in a central office (CO) for FBG sensing. The survivability of an eight-point FBG sensor is examined and analyzed. It is cost effective since the sensing system is entirely centralized in the CO. Experimental results show that the proposed system can enhance the reliability of the FBG sensing network for large-scale and multi-point architecture.

Employing external injection-locked Fabry-Perot laser scheme for mm-wave generation

We propose and experimentally investigate a 170 GHz band millimeter-wave source employing an external dual-mode-locked Fabry-Perot laser diode (FP-LD) with a 1.38 nm mode-spacing. Two continuous-wave (CW) lights are aligned to inject the corresponding modes of FP-LD to generate dual-beat-mode output. The proposed dual-mode laser is not only stable, but also has single-longitudinal-mode (SLM) output characteristics. Moreover, the relationship between two external-injected wavelengths is also analyzed for the dual-wavelength output.