Wavelength-stabilized microcrystal laser

Abstract

A microcrystal laser assembly including a gain-crystal includes a frame having a high thermal conductivity. The frame has a base with two spaced apart portions extending from the base. The gain-crystal has a resonator output mirror on one surface thereof. The gain-crystal is supported on the spaced-apart portions of the frame in the space therebetween. Another resonator minor is supported in that space, spaced apart from the output mirror, on a pedestal attached to the base of the frame. The pedestal and the frame have different CTE. Varying the frame temperature varies the spacing between the resonator mirrors depending on the CTE difference between the pedestal and the frame.

What is claimed is: 
     
         1 . A laser apparatus comprising:
 a base having a channel formed therein, said base having a high thermal conductivity;   a pedestal fitted with within the channel and supported thereby, with the coefficient of thermal expansion of the pedestal being greater than the thermal coefficient of thermal expansion of the base;   a saturable absorber supported by the pedestal and defining a first resonator minor;   a laser gain medium aligned with and spaced from the saturable absorber mirror by an air gap;   a support coupled to the gain medium and to the base; and   a second resonator minor positioned between the support and the gain medium, wherein varying the temperature of the based and pedestal functions to vary the thickness of the air gap to thereby adjust the wavelength output of the laser.   
     
     
         2 . An apparatus as recited in  claim 1 , further including a strain compensator layer positioned between the saturable absorber minor and the pedestal. 
     
     
         3 . An apparatus as recited in  claim 1 , wherein said support is formed from a transparent crystal through which pump light can be transmitted to the gain medium. 
     
     
         4 . An apparatus as recited in  claim 1 , further including a heater element thermally coupled to the base. 
     
     
         5 . An apparatus as recited in  claim 1 , further including a detector for monitoring the output of the laser and generating output signals in response thereto, said signals being supplied to a processor, said processor for controlling the heater element in order to stabilize the output of the laser. 
     
     
         6 . An apparatus as recited in  claim 1 , wherein the pedestal is formed from aluminum. 
     
     
         7 . An apparatus as recited in  claim 1 , wherein the surface of the saturable absorber minor facing the gain medium is provided with a coating to reflect pump beam radiation that has been transmitted through the gain medium. 
     
     
         8 . A laser apparatus comprising:
 a pedestal;   a saturable absorber material defining a first minor mounted on one end of the pedestal;   a solid state gain medium spaced apart from the first minor to define an air gap, said gain medium having a partially transmitting coating thereon on the side opposite the first mirror, said coating defining the output coupler of the laser, with a laser resonator being defined between the first minor and the output coupler;   a support element carrying the gain medium;   a frame, said frame extending along at least a part of the length of the pedestal and across the air gap between the first mirror and the gain medium, and wherein said support element is supported by and thermally coupled to the frame and wherein said pedestal is supported by and is thermally coupled to the frame, and wherein the coefficient of thermal expansion (CTE) of the material forming the frame is lower than the CTE of the material forming the pedestal; and   a Peltier element thermally coupled to the frame for controlling the temperature of the apparatus and wherein a change in temperature varies the thickness of the air gap and accordingly the optical path length of the laser resonator.   
     
     
         9 . An apparatus as recited in  claim 8 , further including a strain compensator layer positioned between the saturable absorber minor and the pedestal. 
     
     
         10 . An apparatus as recited in  claim 8 , further including a detector for monitoring the output of the laser and generating output signals in response thereto, said signals being supplied to a processor, said processor for controlling the Peltier element in order to stabilize the output of the laser. 
     
     
         11 . An apparatus as recited in  claim 8 , wherein the pedestal is formed from aluminum. 
     
     
         12 . An apparatus as recited in  claim 8 , wherein radiation from a pump radiation source is directed into the gain medium through the output coupler. 
     
     
         13 . An apparatus as recited in  claim 8 , wherein the surface of the saturable absorber minor facing the gain medium is provided with a coating to reflect pump beam radiation that has been transmitted through the gain medium.