AN ADAPTIVE WAVELENGTH TUNABLE OPTICAL FILTER EMPLOYING AN ANGLE-TUNED INTERFERENCE FILTER AND AN INTELLIGENT DIGITAL CONTROLLER

This paper describes an adaptive wavelength tunable optical filter, wh ich is composed of an angle-tuned interference optical filter and an i ntelligent digital controller, The new angle-tuned interference filter consists of a dielectric interference optical filter and a piezoelect ric angle-tuning mechanism. It achieves quick wavelength switching wit hin 2.5 ms in a 30 nm tuning range and a sufficiently low crosstalk le ss than -30 dB, The intelligent digital controller has two functions: wavelength tracking and wavelength channel selection, Combining these technologies, we have developed a practical low-cost tunable filter su itable for a post-optical-amplifier filter in a high-sensitivity detec tion system and a channel selector in a WDM system that requires 10-10 0 ms channel selection time, With a wavelength tracking operation, we have confirmed -35 dBm high-sensitivity detection in 20 nm wavelength range in a 10 Gb/s system. We have also confirmed a wavelength channel selection operation within 18 ms in a three-channel wavelength divisi on multiplexed (WDM) system whose channel spacing is 4.4 nm.