A thermally stable Fabry-Perot tunable filter for 1 AA-spaced high-density WDM systems

A new tunable filter using two nonidentical Fabry-Perot etalons arranged on a single rotation stage has been demonstrated. The 3-dB passband, tuning range, and insertion loss were 0.2 AA, 1.2 nm, and 1.5 to 3 dB, respectively. The thermally induced wavelength deviation of the output was within 0.02 AA in the range of 0 to 50 degrees C. The sharp wavelength characteristics and the good temperature stability promised to operate FSK-DD stably where the wavelength spacing of FSK signals was 1 AA.<
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