Noriyasu Shiga

Microsecond switching of parametric tunable dispersion compensator

A record-fast, 2 μs switching operation of an optical tunable dispersion compensator is demonstrated with a parametric tunable dispersion compensation scheme. We alternately switch two optical paths having different net dispersions with a microsecond guard interval of the compensator response and achieve successful transmissions of 43 Gbit/s non-return-to-zero on-off-keying optical signals. The error-free guard time for the switching of the two optical paths is 125 μs, limited mostly by the clock synchronization of the bit-error detector. The power penalty due to the switching of the compensator is less than 0.5 dB.

Less than 0.19-dB transient gain excursion AGC-EDFA with digital control for 20-channel add/drop equivalent operation

We have developed a digitally controlled AGC-EDFA by combining an FF-controlled pump-LD and an FB-controlled VOA. An FPGA is used to finely tune the gain setting of the pump current with a wide dynamic range for input burst signals and to precisely configure the gain and cutoff bandwidth for the loop control of the VOA. We realized a gain excursion of less than 0.19 dB at the AGC-EDFA with the VOA for a 20-channel add/drop equivalent operation. We believe 0.19 dB to be the smallest value yet reported.

Optical packet and circuit simultaneous transmission technologies for dynamic lightpath setup/release and packet traffic change

For dynamic traffic change on packet/lightpath integration, all-bandwidth amplifiers and high dynamic-range packet receivers are developed. 80-Gbit/s colored optical packets and 8-lightpaths simultaneous 170-km field transmission are demonstrated.

Super-Fast AGC-EDFA for the Burst-Mode Systems without Gain Excursion in 20-ns and 21-dB Ramped Input

AGC-EDFA for the burst-mode signals is one of the most important devices in the next generation WDM. We have realized the AGC-EDFA without gain excursion in 20-ns and 21-dB ramped input with the high-speed VOA.

0.2-dB gain excursion AGC-EDFA with a high speed VOA for 100-channel add/drop equivalent operation

We have developed a digitally controlled AGC-EDFA by combining an FF-controlled pump-LD and an FF-controlled VOA. We realized a gain excursion of less than 0.2 dB at a 100-channel add/drop equivalent operation.

Suppression of transients in an EDFA chain using feed-forward pump control and a high-speed VOA

We report on an error-free operation of the survivor channel during instantaneous load and unload of a 7-ms burst signal with 16-dB dynamic range, in cascaded six fast feed-forward AGC-EDFAs assisted by a fast VOA.

Switching mechanism of an optically-gated optical switch using an organic dye

A versatile optically-gated optical switch using an organic-dye is suitable for light-path switching in an optical communication for various wavelengths of a signal-light. An organic dye for absorbing a gating-light combined with a high-boiling solvent for forming a thermal-lens is properly selected choosing a wavelength of both a gating- and a signal-light. The incidence gating-light passed through a short focal-length lens is absorbed around the focal point and form high-temperature region in the high-boiling solvent, which refract a simultaneously incidence signal-light by a thermal-lens effect. Mechanism of forming a thermal-lens and refracting the signal-light is discussed.

Transient performance of ultra-fast AGC-EDFA in 40-channel add/drop operation

We have achieved a good gain transient performance of an ultra-fast AGC-EDFA in 40-channel add/drop operation owing to the combination of an electrically controlled pump LD and a high-speed VOA.

Switching mechanism of an all-optical switch using pulsed gating

A versatile optically gated optical switch using an organic dye is suitable for light-path switching in an optical communication device for various wavelengths of the signal light. We have developed two types of all-optical switch, i.e., a coaxial configuration and a different-axis configuration. The coaxial configuration exhibits a faster response (~80 µs) than the different-axis configuration (~3 ms). Here, the response time of the signal light (1310 nm) is analyzed as a function of both the gating power (pulse height) and pulse width of the gating light (980 nm). The heating and propagation processes in a tiny area around the focal point of both the signal light and the gating light are discussed.

Less than 0.5-dB gain excursion AGC-EDFA with a high speed FB/FF-controlled VOA for a wide operation range

We have developed a digitally controlled AGC-EDFA by combining an FF-controlled pump-LD and a high-speed FB/FF-controlled VOA. We realized a gain excursion of less than 0.5 dB for a wide operation range.