An optic reference signal generator comprising a housing forming an enclosed space with one or more air flow openings. Within the housing is an optic signal generator driver configured to generate an optic signal generator drive signal. An optic signal generator generates an optic signal responsive to the optic signal generator drive signal. A polarity control unit adjusts polarization of the optic signal to create a polarization adjusted optic signal and a modulator bias generator and controller generates a modulation signal. A pattern signal input receives a pattern signal and a modulator receives the polarization adjusted optic signal, the pattern signal, and the modulation signal to generate a modulated output signal.