A tunable laser, including: a laser resonant cavity including first and second total reflection mirrors within a laser spectral range; first and second wavelength-adjustable laser gain mediums disposed in the laser resonant cavity; first and second intra-cavity collimating lenses; an acousto-optic tunable filter; a device exciting sound waves in an acousto-optic crystal and including a sound wave energy transducer bonded on a selected surface of the crystal; a radio frequency signal source; an optical phase modulator; an optical etalon disposed between the optical phase modulator and the laser gain medium; a wavelength locker disposed at one of zero-order diffraction optical paths of intra-cavity light; a pigtailed collimator coupling laser output light to an optical fiber; first and second pumping devices exciting the first and second laser gain mediums respectively; an optical phase modulator driver for driving the phase modulator; and a signal control processing circuit.