Hee Sang Chung

Suppression of transient phenomena in hybrid Raman/EDF amplifier

Transient phenomena of hybrid Raman/erbium-doped fiber amplifier (EDFA) upon optical channel add-drop are investigated. The transient responses of surviving channels are resulted from the combined dynamics of Raman amplifier and EDFA. It is shown that the suggested method employing fast gain control of EDFA only can effectively suppress the transient variation of output power. The transient-suppressing hybrid Raman/EDFA is proven to be enough for wavelength-division-multiplexing networks including reconfigurable optical add-drop multiplexer and/or transparent optical cross-connect, if the optical switching speed is carefully chosen.

Bidirectional transmissions of 32 channels /spl times/ 10 Gb/s over metropolitan networks using linear optical amplifiers

This letter demonstrates bidirectional transmissions of 320 Gb/s (160 Gb/s per direction) over metropolitan networks using linear optical amplifiers (LOAs) as bidirectional inline amplifiers. The bidirectional transmissions resulted in 18.5 dB (of worst) Q factor over three spans of 40-km single-mode fiber, and 17.6 dB over four spans, thus, proving the feasibility of the LOAs as the bidirectional amplifiers.

Transmission Performance Comparison of Hybrid Fiber Amplifier

Hybrid fiber amplifier (HFA) has the advantages of low noise figure and high output power. The transmission performance is better than conventional EDFA by >1.0 dB of Q-factor in 720 km SMF transmission.

A low-noise L-band EDFA with a 1500-nm Raman-pumped dispersion-compensating fiber section

This report presents a low-noise L-band erbium-doped fiber amplifier (EDFA) with a dispersion-compensating Raman amplifier. With an optimized prestage and 1500-nm Raman-pump laser diodes, the proposed EDFA achieved an internal noise figure of less than 4.5 dB over a 33-nm flat gain bandwidth within 0.5 dB at -2 dBm of large signal input power.

A simple and low-cost 1625 nm OTDR monitoring system for 350 km WDM networks

An SOA-based 1625 nm OTDR (optical time domain reflectometry) monitoring system in a bypass configuration is successfully demonstrated for a 350 km WDM network. No power penalty is observed in the 10 Gb/s WDM transmissions when the OTDR signal is on.

A variable gain optical amplifier for metro WDM networks with mixed span losses: a gain-clamped semiconductor optical amplifier combined with a Raman fiber amplifier

A variable-gain optical amplifier for metro-WDM networks of mixed span losses is demonstrated. It consists of low-gain Raman-fiber-amplifier and gain-clamped SOA. 16/spl times/10 Gb/s signals were successfully transmitted over 170 km (87dB) of mixed span losses under dynamic add/drops.

Transient power suppression in Raman amplifier with multi-wavelength pumping upon channel add-drop

Fast gain control method in Raman amplifier with multi-wavelength pumping scheme is presented. Transient power excursion is controlled within 0.2 dB at 6 dB channel add-drop in C-band Raman amplifier with two wavelength pumps

An optical amplifier for metro WDM networks, based on a gain-clamped semiconductor optical amplifier

An optical amplifier for metro WDM networks, based on a gain-clamped semiconductor optical amplifier is proposed. The amplifier (RAGCSOA) consists of a low gain Raman fiber amplifier and a gain-clamped semiconductor optical amplifier. The RAGCSOA has over 20 dB gain and a noise figure below 3 dB. In addition, the potentially compact amplifier shows negligible transients under dynamic add-drops. Sixteen channels of 10 Gb/s signals were successfully transmitted over five NZDSF spans of 80 km using RAGCSOAs. RAGCSOAs were also used to successfully transmit sixteen channels of 10 Gb/s WDM signals over four 40km spans of SMF with add-drops. No penalty was observed when 15 out of 16 channels were dynamically add/dropped in all the transmission systems. The RAGCSOA can be very compact when a GCSOA chip and a Raman pump LD chip are packaged in a module.

Novel method of gain clamping in C-band erbium dopedfiber amplifier

A novel technique of gain clamping in C-band erbium-doped fiber amplifiers (EDFAs) is presented. It uses a single fiber Bragg grating (FBC) on the input side of erbium-doped fiber (EDF) to reflect a portion of backward amplified spontaneous emission (ASE) back into EDFA. A gain clamping is achieved in EDFA with FBC when the input power dynamic range varies from –36.0 dBm to –4.0 dBm. Efficient flat-gain spectrum in C-band EDFAs is achieved by adding a FBG and it is compared with a conventional EDFA without FBG.

Transient behavior of C-band EDFA under various wavelength allocations of add/drop channels

We report the wavelength-dependent gain variation of a C-band EDFA under dynamic channel add/drop. The optical power transient varies with the assignment of the wavelength of the add/drop channels while the total number of channel is kept constant. The change of gain according to the channel wavelength allocation also occurs in the steady state.