Patent ID: 8369367

Claim:
A tunable laser comprising: an end mirror having prescribed reflectivity to form a laser cavity; a wavelength tunable laser gain medium disposed in the laser cavity and capable of laser oscillation in a lasing wavelength spectrum of a prescribed range; an intracavity collimating lens; a wavelength tunable filter comprising a single acousto-optic crystal and a single acoustical transducer bonded to a selected surface of the crystal, disposed in the laser cavity and to which is inputted an outgoing light from the wavelength tunable laser gain medium by the intracavity collimating lens, wherein the intracavity collimating lens collimates laser beam inputs to the wavelength tunable filter; an intracavity reflection mirror, wherein the intracavity reflection mirror and end mirror are on opposite sides of the crystal, wherein the transducer excites an acoustic wave in the crystal, the intracavity reflection mirror has approximately 100 percent reflectivity for the lasing wavelength spectrum, the wavelength tunable filter diffracts an incoming light beam which results in a first diffracted light having a positive wavelength shift relative to the incoming light beam, the first diffracted light is reflected by the intracavity reflection mirror back to the crystal at a Bragg angle, the wavelength tunable filter diffracts this reflected first diffracted light which results in a second diffracted light having a negative wavelength shift relative to the first diffracted light, and an overall wavelength shift of the first and second diffracted lights is zero, the second diffracted light is then reflected by the end mirror back to the crystal, returns to the intracavity reflection mirror from the crystal, is reflected and again passes through the crystal to the lens; a source of radio frequency electrical power for providing radio frequency energy to the transducer for tuning a cavity oscillation wavelength by changing the radio frequency; means for exciting the wavelength tunable laser gain medium; an active phase modulator; means for driving the active phase modulator; and means for control signal processing.