A small-form-factor fiber optic tunable filter kit from Ondax Inc. features integrated control electronics and an RS-232 interface for control via a PC. The instrument includes a graphical user interface for use with Linux and with Windows 98, 2000 and XP. The company says that the filter, which operates from 1528.1 to 1562.8 nm, exhibits absolute spectral accuracy and repeatability of ±3 GHz. The optical module has typical insertion loss of <4 dB, and isolation of 18 dB at 50 GHz and 30 dB at 100 GHz from the channel center. Minimum passband width is 15 GHz.