Share Email Print
cover

Proceedings Paper

Feedback module for evaluating optical-power stabilization methods
Author(s): John Downing
Format Member Price Non-Member Price
PDF $14.40 $18.00

Paper Abstract

A feedback module for evaluating the efficacy of optical-power stabilization without thermoelectric coolers (TECs) is described. The module comprises a pickoff optic for sampling a light beam, a photodiode for converting the sample power to electrical current, and a temperature sensor. The components are mounted on an optical bench that makes accurate (0.05°) beam alignment practical as well as providing high thermal-conductivity among the components. The module can be mounted on existing light sources or the components can be incorporated in new designs. Evaluations of optical and electronic stabilization methods are also reported. The optical method combines a novel, weakly reflective, weakly polarizing coating on the pickoff optic with a photodiode and an automatic-power-control (APC) circuit in a closed loop. The shift of emitter wavelength with temperature, coupled with the wavelength-dependent reflectance of the pickoff optic, enable the APC circuit to compensate for temperature errors. In the electronic method, a mixed-signal processor in a quasiclosed loop generates a control signal from temperature and photocurrent inputs and feeds it back to an APC circuit to compensate for temperature errors. These methods result in temperature coefficients less than 20 ppm/°C and relative rms power equal to 05% for the optical method and 0.02% for the electronic method. The later value represents an order of magnitude improvement over rms specifications for cooled, laser-diode modules and a five-fold improvement in wall-plug efficiency is achieved by eliminating TECs.

Paper Details

Date Published: 22 April 2016
PDF: 9 pages
Proc. SPIE 9730, Components and Packaging for Laser Systems II, 97300B (22 April 2016); doi: 10.1117/12.2208800
Show Author Affiliations
John Downing, USL Technologies LLC (United States)


Published in SPIE Proceedings Vol. 9730:
Components and Packaging for Laser Systems II
Alexei L. Glebov; Paul O. Leisher, Editor(s)

© SPIE. Terms of Use
Back to Top