Y.K. Chen

Passive gain-equalized wide-band erbium-doped fiber amplifier using samarium-doped fiber

A passive gain-equalization technique of erbium-doped fiber amplifier (EDFA) using a samarium-doped fiber to obtain wide-band flattened gain operation is reported. In the wavelength range from 1529-1559-nm, small inter-channel gain variations can be achieved. This simple technique is suitable for multiwavelength wide-band in-line-amplifier cascaded transmission applications.

Low-crosstalk and compact optical add-drop multiplexer using a multiport circulator and fiber Bragg gratings

Three kinds of low-crosstalk and compact optical add-drop multiplexers (OADMs) based on a multiport optical circulator (MOC) with fiber Bragg gratings are proposed and demonstrated. For the MOC-based structure, there is a significant intraband crosstalk reduction of about 37 and 16 dB on the dropped and added channels, respectively, for the best proposed MOC-based structure as compared with the conventional structure. Bit-error rate performance and both intraband and interband crosstalk-induced power penalties of these MOC-based OADMs are examined in a 10 Gb/s system demonstration. Such a low-crosstalk, miniaturized, and compact OADM may find important applications in dense wavelength-division multiplexing networks.

Hybrid 10-Gb/s, 2.5-Gb/s, 64-QAM, and AM-VSB high-capacity wavelength-division-multiplexing transport systems using SMF and LEAF fibers

A four-wavelength high-capacity hybrid wavelength-division-multiplexing (WDM) system separately over 100-km standard single-mode fiber and nonzero dispersion-shifted fiber of large effective area fiber is demonstrated. The WDM wavelengths contain one 10-Gb/s signal, one 2.5-Gb/s signal, one 64-quadrature amplitude modulator signal of 110 channels, and one amplitude module with vestigial sideband signal of 80 channels. Satisfaction of a huge variety of receiving requirements and reduction of fiber nonlinearities-induced degradations by controlling channel powers are also considered. Such a hybrid WDM system would be attractive for multiservice trunk applications in advanced transport systems for providing both CATV and telecommunication services.A four-wavelength high-capacity hybrid wavelength-division-multiplexing (WDM) system separately over 100-km standard single-mode fiber and nonzero dispersion-shifted fiber of large effective area fiber is demonstrated. The WDM wavelengths contain one 10-Gb/s signal, one 2.5-Gb/s signal, one 64-quadrature amplitude modulator signal of 110 channels, and one amplitude module with vestigial sideband signal of 80 channels. Satisfaction of a huge variety of receiving requirements and reduction of fiber nonlinearities-induced degradations by controlling channel powers are also considered. Such a hybrid WDM system would be attractive for multiservice trunk applications in advanced transport systems for providing both CATV and telecommunication services.

Characteristic comparison of single-pumped L-band erbium-doped fiber amplified spontaneous emission sources

We experimentally investigate the single-pumped L-band (1570–1610 nm) erbium-doped fiber amplified spontaneous emission (ASE) source in four configurations with single-pass forward, single-pass backward, double-pass forward (DPF), and double-pass backward structures. The characteristics are examined and compared in terms of the output power, mean wavelength, spectral linewidth, and pumping conversion efficiency. Among them, only DPF configuration is satisfied, and other configurations are intrinsically hard to be an L-band ASE source for applications. Such results are significantly different as compared with their corresponding C-band counterparts.

Demonstration of in-service supervisory repeaterless bidirectional wavelength-division-multiplexing transmission system

An in-service supervisory repeaterless bidirectional wavelength-division-multiplexing (WDM) transmission system using optical fiber amplifiers is demonstrated for the first time. The system supervision by an optical time domain reflectometer (OTDR) is achieved without degrading the 2.5 Gb/s service over a bidirectional six-WDM-channel 200-km single-fiber link. Negligible system penalties of dispersion and counter-directional transmission crosstalk are observed.<<ETX>>

In-service OTDR-monitoring-supported fiber-Bragg-grating optical add-drop multiplexers

Two optical time-domain reflectometer (OTDR)-monitoring-supported fiber-Bragg-grating optical add-drop multiplexer (OADM) structures for in-service fault-location monitoring by using a conventional OTDR are demonstrated. Negligible system power penalty, due to the OTDR monitoring, of both structures in 10-Gb/s dense wavelength-division-multiplexing (DWDM) link is achieved. We find that the multiport-optical-circulator-based structure is superior to the wavelength-division-multiplexing structure to have compact structure, fewer components required, and potentially low cost. Such OADMs may find important applications in DWDM networks to implement a centralized automated in-service surveillance system to enhance system reliability.

In-service supervisory EDFA-repeated wavelength division multiplexing transmission system

An in-service supervisory wavelength division multiplexing (WDM) transmission system is demonstrated for the first time. Simultaneous fault location and EDFA status-monitoring are achieved without degrading the 2.5 Gb/s service in a five-EDFA, 365-km, four-WDM-channel system.<<ETX>>

High-power flat L-band erbium-doped fiber ASE source using dual forward-pumping scheme

We experimentally investigate a high output power L-band (1565–1605 nm) erbium-doped fiber amplified spontaneous emission (ASE) source using dual forward-pumping configuration. Such configuration allows high pumping-power operation and enhances the pumping efficiency. The high pumping efficiency of 36.1% is achieved for such ASE source with a mirror reflectance of 30%. The output power of about 72.2 mW and a linewidth of 40.8 nm with a power ripple of 0.7 dB are obtained without using any external spectral filters.

Multiwavelength erbium-doped power limiting amplifier in all-optical self-healing ring network

A multiwavelength self-healing interoffice all-optical protection ring network requires optical amplifiers with a large dynamic range. We demonstrate that an erbium-doped multiwavelength optical power limiting amplifier (OLA) fulfils the dynamic range requirement. A single three-WDM-channel OLA serving the ring size of 150 km at channel rates of 2.488 Gb/s is presented.A multiwavelength self-healing interoffice all-optical protection ring network requires optical amplifiers with a large dynamic range. We demonstrate that an erbium-doped multiwavelength optical power limiting amplifier (OLA) fulfils the dynamic range requirement. A single three-WDM-channel OLA serving the ring size of 150 km at channel rates of 2.488 Gb/s is presented.

Chirped fiber-grating-integrated optical limiting amplifier for dispersion compensation

Recently, erbium-doped fiber amplifiers (EDFAs) have made rapid progress in the 1.55-/spl mu/m band optical fiber transmission. However, high bit rate transmission is restricted by large chromatic dispersion of the conventional simple mode fiber (SMF) unless compensating techniques are used. The chirped fiber gratings (CFGs) are attractive as they are passive linear devices, with highly related dispersion, compact size and are relatively easy to fabricate. Using CFGs for dispersion compensation, the EDFAs are inserted repeatedly between SMF and optical circulators (OCs) in order to amplify the signals. However, the repeated spacing is limited by the loss of CFGs, SMF and OCs. In this report, by inserting a bi-directional EDFA between the OC and CFGs, we proposed an optical limiting amplifier (OLA) configuration in multi-wavelength for dispersion compensation. The link budget and dynamic range characteristics, bit-error-rate (BER) performance as well as the eye-diagram of the modulated signals were investigated and discussed.