POLARIZATION-INDEPENDENT SEMICONDUCTOR OPTICAL AMPLIFIER GATE AND ITSAPPLICATION IN WDM SYSTEMS

We studied 2 types of polarization insensitive semiconductor optical a mplifier (SOA) gates for use in wavelength division multiplexing (WDM) applications: 1) a low operation current SOA gate with a small and sq uare bulk active region but without spot-size converters and 2) a mult i channel SOA gate array with tapered waveguide spot-size converters ( SS-SOA)on both sides. The low operation current SOA gate provided a ve ry low current for fiber-to-fiber loss-less operation (5.4-7.0 mA) and a high extinction ratio (> 30 dB) over a wide wavelength range (1530- 1580 nm). For multi channel array assembling, the SS is indispensable. The 4-channel SS-SOA gate array was assembled on a planar lightwave c ircuit (PLC) platform for the first time. The gain characteristics of each channel were very similar and a low fiber-to-fiber loss-less curr ent of 33 mA and a high extinction ratio of nearly 40 dB were achieved in all channels. The polarization dependence was less than 1 dB. Usin g the fully packaged 4-channel hybrid gate array module (a 4 channel S S-SOA on PLC platform), an ultra-wide-band (1530 -1600nm) high speed w avelength selector was successfully demonstrated. Both rise- and Fall- times were less than ins, which makes the wavelength selector suitable for high-speed optical packet switching. Electrical and optical inter ference between channels were negligible.