Patent ID: 7903704
Filing Date: 2011-03-08
Classification: B82Y,G01N,H01S

Abstract:
1. A method for obtaining power-maximized continuous tuning for a coupled cavity laser system, the steps comprising: a) powering a quantum cascade laser (QCL) gain chip to provide a source of multiwavelength laser light at a first power level; b) selectively reflecting said multiwavelength laser light with a diffraction grating in a cavity back to said QCL, gain chip to select a first laser wavelength; c) adjusting a position of said diffraction grating with a piezoelectric translator (PZT) to adjust a distance of said cavity to obtain a maximum output distance for said first laser wavelength and said first power level, said maximum output distance maximizing output of the laser system at said first laser wavelength, said position of said diffraction grating, selectively altered on the order of a few wavelengths of said first laser frequency to find said maximum output distance; d) making a fine angular displacement step with said diffraction grating to select a new laser wavelength and repeating steps b and c in an ongoing fashion for each new laser wavelength to obtain sufficient data to determine Fabry-Perot (FP) mode comb peaks for said QCL gain chip at said first power level over a desired wavelength range; e) determining a maximizing power level for said first wavelength by determining a mode comb power level of the QCL gain chip that causes a mode comb wavelength spike of said QCL gain chip to coincide with said first laser wavelength, said maximizing power level achieved by determining a first power level change to shift one of said laser output peaks a first known fractional FP mode distance to determine ΔI  where I f) incrementing or decrementing a selected determined maximizing power level to match a second selected laser wavelength within said wavelength range and shifting said maximizing power level a free spectral range amount when needed to maintain said maximizing power level within preferred power limits of said source while simultaneously matching said first laser wavelength; g) adjusting a position of said diffraction grating at said maximum output distance with said piezoelectric translator (PZT) to ensure that said selected maximum output distance for said selected wavelength is as much a maximum output distance as possible to enable maximum output of the laser system at said selected laser wavelength; whereby the coupled cavity laser system operates at a maximum for a selected wavelength within said wavelength range by selecting and ensuring said maximum output distance and said maximizing power level for said selected wavelength.