Laser system having switchable power modes

Abstract

A pump module comprises a power source, a plurality of laser diodes, a controller and light combining optics. The laser diodes each have an activated state and a deactivated state. The laser diodes receive current from the power source and output light when in the activated state and do not receive current from the power source when in the deactivated state. The controller switches the plurality of laser diodes from a first power mode, in which a first subset of the laser diodes is in the activated state, to a second power mode, in which a second subset of the laser diodes is in the activated state, responsive to a power mode setting. The light combining optics are configured to combine the light from the activated laser diodes and output the combined light as pump energy. A laser system comprises a pump module and a gain medium. The pump module is configured to output pump energy having a wavelength that is within a wavelength range of 874-881 nm. The gain medium is in the path of the pump energy and is configured to absorb the pump energy and emit laser light responsive to the absorbed pump energy. In one embodiment, a controller switches a power level of the pump energy between first and second power levels responsive to a power mode setting input from an operator.

1 . A laser pump module ( 104 ) having a variable pump energy power output, the module comprising:
 a power source ( 128 );   a plurality of laser diodes ( 122 ) each having an activated state and a deactivated state, wherein the laser diodes receive current from the power source and output light when in the activated state and do not receive current from the power source when in the deactivated state;   a controller ( 130 ) that switches the plurality of laser diodes from a first power mode, in which a first subset of the laser diodes is in the activated state, to a second power mode, in which a second subset of the laser diodes is in the activated state, responsive to a power mode setting ( 180 ); and   light combining optics ( 124 ) configured to combine the light from the activated laser diodes and output the combined light as pump energy ( 108 ).   
     
     
         2 . The module of  claim 1 , wherein:
 the power source comprises a current source; and   the controller selectively enables current flow from the current source to the activated laser diodes and disables current flow from the current source to the deactivated laser diodes responsive to the power mode setting.   
     
     
         3 . The module of  claim 1 , wherein the pump energy has a wavelength in a range of 874-881 nm. 
     
     
         4 . The module of  claim 1 , wherein the light combining optics comprise:
 a plurality of optical fibers ( 142 ) each configured to transmit the light output from one of the laser diodes; and   a combiner ( 144 ) configured to receive the light transmitted by the plurality of optical fibers and combine the transmitted light into the pump energy.   
     
     
         5 . The module of  claim 1 , wherein the light combining optics comprise homogenizing and collimating optics ( 134  and  136 ) configured to combine the light output from the plurality of laser diodes into the pump energy. 
     
     
         6 . The module of  claim 1 , wherein the controller is configured to adjust the current to the activated laser diodes. 
     
     
         7 . The module of  claim 1 , wherein the power of the pump energy is in a range of 50-300 W in the first power mode and is in a range of 500-1000 W when in the second power mode. 
     
     
         8 . A laser system ( 100 ) comprising:
 a pump module ( 104 ) configured to output pump energy ( 108 ) having a wavelength within a wavelength range of 874-881 nm; and   a gain medium ( 102 ) in the path of the pump energy, the gain medium configured to absorb the pump energy and emit laser light ( 112 ) responsive to the absorbed pump energy.   
     
     
         9 . The laser system of  claim 8 , wherein:
 the pump module is configured to output the pump energy at first and second power levels; and   the system comprises a controller ( 130 ) that switches the power level of the pump energy between the first and second power levels responsive to a power mode setting ( 180 ) input from an operator.   
     
     
         10 . The system of  claim 9 , wherein the gain medium comprises a yttrium-aluminum-garnet (YAG) crystal rod with neodymium atoms dispersed in the YAG rod. 
     
     
         11 . The system of  claim 9 , wherein the first and second power levels are separated by at least 50 W. 
     
     
         12 . The system of  claim 9 , wherein the pump module comprises:
 a plurality of laser diodes ( 122 ) each having an activated state and a deactivated state, wherein the laser diodes output light ( 138 ) when in the activated state and do not output light when in the deactivated state; and   light combining optics ( 124 ) configured to combine the light from the laser diodes and output the combined light as the pump energy;   wherein the controller selectively sets subsets of the plurality of laser diodes in one of the activated state and the deactivated state responsive to the power mode setting.   
     
     
         13 . The system of  claim 12 , wherein the light combining optics comprise:
 a plurality of optical fibers ( 142 ) each configured to transmit the light output from one of the laser diodes; and   a combiner ( 144 ) configured to receive the light transmitted by the plurality of optical fibers and combine the transmitted light into the pump energy.   
     
     
         14 . The system of  claim 12 , wherein the light combining optics comprise homogenizing and collimating optics ( 134  and  136 ) configured to combine the light output from the plurality of activated laser diodes into the pump energy. 
     
     
         15 . The system of  claim 9 , wherein the laser pump module comprises:
 a plurality of laser diodes ( 122 ) configured output light ( 138 ); and   light combining optics ( 124 ) configured to combine the light from the laser diodes and output the combined light as the pump energy;   wherein the controller varies a current supplied to the laser diodes responsive to the power mode setting to switch the laser pump module between the first and second power levels.   
     
     
         16 . A method comprising:
 providing ( 210 ) a laser pump module ( 104 ) configured to output pump energy ( 108 ) at first and second power levels, wherein the wavelength of the pump energy is within a wavelength range of 874-881 nm at the first and second power levels;   providing ( 212 ) a gain medium ( 102 ) in the path of the pump energy;   providing ( 214 ) a controller ( 130 );   producing ( 215 ) the pump energy at the first power level;   emitting ( 216 ) laser light ( 112 ) from the gain medium at a first power level responsive to absorption of the pump energy;   receiving ( 218 ) a power mode setting ( 180 ) from an operator;   switching ( 220 ) the power level of the pump energy from the first power level to the second power level responsive to the power mode setting using the controller; and   emitting ( 222 ) laser light from the gain medium at a second power level responsive to the absorption of the pump energy.   
     
     
         17 . The method of  claim 16 , wherein providing a gain medium comprises providing a gain medium comprising a yttrium-aluminum-garnet (YAG) crystal rod with neodymium atoms dispersed in the YAG rod. 
     
     
         18 . The method of  claim 17 , wherein the absorption coefficient of the gain medium within the wavelength range of 874-881 nm is greater than 90%. 
     
     
         19 . The method of  claim 16 , wherein:
 providing a laser pump module comprises providing a laser pump module comprising a plurality of laser diodes ( 122 ); and   switching the power level of the pump energy between the first and second power levels comprises activating or deactivating a subset of the laser diodes using the controller.   
     
     
         20 . The method of  claim 16 , wherein:
 providing a laser pump module comprises providing a laser pump module comprising a plurality of laser diodes; and   switching the power level of the pump energy between the first and second power levels comprises adjusting a current to the laser diodes using the controller.