An optical device, such as a vertical cavity surface emitting laser (VCSEL) may be housed in a hermetic enclosure such as a transistor-outline (TO) can and form part of a transmitter optical subassembly (TOSA). The TOSA may be connected to a printed circuit board (PCB) with a flexible circuit. A heating element provided on the flexible circuit heats the hermetic enclosure to improve radio frequency (RF) performance of the optical device in cold ambient conditions.