Ultra small packaged tunable laser assembly

An external cavity tunable laser, comprising:

• a gain medium module to generate a broadband optical spectrum covering a predetermined wavelength range, the gain medium module comprising a gain medium chip with a gain medium waveguide;
• one or more heaters with one heater proximal the gain medium waveguide;
• electrical connections to apply a dither signal to the heater for wavelength locking;
• a collimating lens turning a diverging beam into a collimated beam;
• a pair of etalons to tune frequency;
• an actuator to adjust an external cavity optical path length;
• a bandpass filter to block one or more frequencies outside the predetermined wavelength range;
• a beam splitter to split a percentage of the collimated beam to a photodetector;
• a reflection mirror for feedback to the gain medium waveguide;
• an isolator for preventing reflecting light back to the external cavity;
• and
• a hermetically sealed housing less than 0.15 cubic centimeters.