Simple and compact laser wavelength locker

Abstract

A wavelength locker for monitoring the wavelength drift of a laser uses a pair of detectors for detecting a power component of the laser beam and a wavelength component of the laser beam, respectively. Various positionings of the power detector and/or variations to the collimating lens provide a compact arrangement with fewer components.

1 - 6 . (canceled)  
   
   
       7 . A wavelength locker comprising: a first detector; a second detector; a collimating lens having first end to receive a monitored beam and a second end having an angled polished face to split said monitored beam between said first detector and said second detector; and a filter between said collimating lens and at least one of said first detector and said second detector.  
   
   
       8 . The wavelength locker are recited in  claim 7  wherein said angled polished face is a 45 degree angle to an optical axis of said collimating lens.  
   
   
       9 . The wavelength locker as recited in  claim 8  wherein said first detector is positioned along the optical axis of said collimating lens and said second detector is positioned perpendicular to said optical axis of said collimating lens.  
   
   
       10 . The wavelength locker as recited in  claim 9  wherein said filter is positioned between said collimating lens and said second detector.  
   
   
       11 . The wavelength locker as recited in  claim 9  wherein said filter comprises a thin film filter applied directly to the polished face of said collimating lens.  
   
   
       12 . A method of monitoring a wavelength of a beam, comprising: providing a lens having an angled polished face; collimating a monitored beam with said lens; splitting said collimated beam into a first beam and a second beam with said angled polished face of said lens; wavelength filtering at least one of said first beam and said second beam; detecting said first beam with a first detector to output a first signal detecting said second beam with a second detector to output a second signal; and using said first signal and said second signal to determine a wavelength of said monitored beam.  
   
   
       13 . The method of monitoring a wavelength of a beam as recited in  claim 12  wherein said angled polished face comprises a 45 degree angle to an optical axis of said lens.  
   
   
       14 . The method of monitoring a wavelength of a beam are recited in  claim 12  further comprising: placing a wavelength filter between said second detector and said lens.  
   
   
       15 . The method of monitoring a wavelength of a beam as recited in  claim 12  further comprising: placing a thin film wavelength filter directly in said angled polished face of said lens.  
   
   
       16 . A wavelength locker comprising: a lens to collimate a monitored beam from a light source; a partially reflective coating on one end of said lens to allow a first portion of said monitored beam to pass and to reflect back a second portion of said monitored beam through said lens; a filter to filter said first portion of said monitored beam; a first detector to detect the filtered first portion of said monitored beam; and a second detector positioned adjacent to said light source to detect said second portion of said monitored beam reflected back through said lens.  
   
   
       17 . The wavelength locker as recited in  claim 16  wherein said lens is a gradient index (GRIN) lens.  
   
   
       18 . The wavelength locker as recited in  claim 16  wherein said partially reflective coating reflects approximately 70% of said monitored beam back through said lens.  
   
   
       19 . A method of monitoring a wavelength of a monitored beam comprising: collimating a monitored beam with a lens; allowing a first portion of said monitored beam to pass through the lens wavelength filtering said first portion of said monitored beam; detecting said first portion of said monitored beam; reflecting back a second portion of said monitored beam through said lens to produce a first signal; detecting said second portion of said monitored beam to produce a second signal; and using said first signal and said second signal to determine a wavelength of said monitored beam.  
   
   
       20 . The method of monitoring a wavelength of a monitored beam as recited in  claim 19  wherein said second portion of said monitored beam comprises approximately 70% of said monitored beam.