Use of electronically controlled polarization elements for the initiation and optimization of laser mode-locking
AssigneeThorlabs, Inc.
InventorsDavid Winters, Matthew S. Kirchner, Sterling J. Backus
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Abstract
Apparatus for modelocking a fiber laser cavity includes two variable retarder assemblies and a polarizing element. The variable retarder assemblies each have two electronically addressable elements and one fixed element. The first variable retarder assembly prepares a polarization state suitable for NPE modelocking to be launched into the fiber, and the second variable retarder assembly controls the polarization state after exiting the fiber, before being incident on the polarizing element. A control system controls the electronically addressable phase retarders in order to create and modify conditions for modelocking the fiber laser.
Claims20
Apparatus for modelocking a fiber laser which is configured to produce laser output light given pump laser input light comprising:
- a first variable retarder assembly;
- a section of optical fiber providing a nonlinear change to a polarization state of light;
- a second variable retarder assembly;
- a polarizing element for outputting low intensity light providing saturable loss;
- and
- a control system;
- wherein the first assembly includes two electronically addressed variable phase retarders and a single fixed phase retarder;
- wherein the first assembly is configured to prepare a polarization state of light suitable for nonlinear polarization evolution (NPE) modelocking to launch into the optical fiber;
- wherein the second assembly includes two electronically addressed variable phase retarders and a single fixed phase retarder;
- wherein the second assembly is configured to control a polarization state of light received from the optical fiber before being incident on the polarizing element;
- and
- wherein the control system is configured to control the variable phase retarders.
The method of modelocking a fiber laser comprising the steps of:
- providing first and second variable retarder assemblies, each having two liquid crystals and a single fixed wave plate;
- providing a section of optical fiber configured to provide a nonlinear change to a polarization state of light in the laser;
- providing a polarizing element for outputting low intensity light from the laser to provide saturable loss;
- electronically addressing the liquid crystals in one assembly to prepare a polarization state of light suitable for nonlinear polarization evolution (NPE) modelocking and launching it into the optical fiber;
- electronically addressing the liquid crystals in the other assembly to vary polarization of light received from the fiber, and providing it to polarizing element;
- measuring aspects of laser performance related to modelocking;
- calculating an error based on the measured aspects of laser performance and desired aspects of laser performance;
- and
- modifying retardance of the liquid crystals based upon the calculated error.
Dependencies are inferred from the claim text.