Simple and compact laser wavelength locker
View Patent ↗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. A wavelength locker, comprising:
a lens to collimate a monitored beam from a light source to produce a collimated beam;
a filter to filter the collimated beam to output a filtered beam;
a first detector to detect the filtered beam; and
a second detector positioned in a path of the monitored beam between the light source and said lens.
2. The wavelength locker as recited in claim 1 , wherein said first detector produces a first signal which is a function of the monitored beam power and the second detector produces a second signal which is a function of the monitored beam wavelength.
3. The wavelength locker as recited in claim 1 wherein said second detector is positioned approximately 5-15 μm in front of the light source.
4. The wavelength locker as recited in claim 1 wherein said second detector is positioned approximately 5-15 μm in front of the light source and approximately 20-40 μm to one side of the light source.
5. A method for operating a wavelength locker, comprising:
collimating a monitored beam from a source to produce a collimated beam;
filtering the collimated beam and outputting a filtered beam;
detecting the filtered beam and producing a first signal as a function of monitored beam wavelength; and
detecting the monitored beam emerging from the light source prior to collimating and producing a second signal as a function of the monitored beam power.
6. A method for operating a wavelength locker are recited in claim 5 , further comprising:
operating on said first signal and said second signal to determine a wavelength of the monitored beam.
7. An optical system, comprising:
a laser, having a front facet and a back facet, mounted on a substrate;
a collimating lens positioned to receive an unfiltered beam emerging from said back facet;
an etalon positioned behind said collimating lens to filter the unfiltered beam;
a first light detector positioned behind said etalon to receive the filtered beam emerging from said etalon;
a second light detector mounted on said substrate with said laser between said back facet and said collimating lens to receive the unfiltered beam emerging from said back facet; and
a controller to receive a first signal from said first detector and a second signal from said second detector to determine a wavelength of a beam from said front facet of said laser.
8. The optical system as recited in claim 7 wherein said second light detector is positioned anywhere within a cone shaped path of the unfiltered beam.
9. The optical system as recited in claim 7 , wherein said second light detector is positioned approximately 5-15 μm from said back facet.
10. The optical system as recited in claim 7 wherein said second light detector is positioned approximately 5-15 μm in front of said back facet and approximately 20μ40 μm to one side of said back facet.