A tunable laser configured in a small package coupled to a printed circuit board. The tunable laser includes a housing with a volume formed by exterior walls. An electrical input interface is positioned at the first end of the housing. An optical output interface is positioned at the second end of the housing and configured to transmit a continuous wave optical beam. A semiconductor optical amplifier or gain chip produces an optical output beam, and an optical isolator is positioned directly downstream of the gain chip to prevent the incoming light from the downstream optics from reflecting back though the isolator and into the cavity of the laser. A beam splitter directs a portion of the light transmitted through the isolator back into the other end of the gain chip.