Measurement of losses in optical components using filtered optical feedback cavity ring down technique

A filtered optical feedback cavity ring down (FOF-CRD) technique employing a continuous wave Fabry-Perot diode laser is employed to measure the total optical losses, i.e., absorption and scattering in optical components with arbitrary thickness. The FOF from the ring down cavity (RDC) is re-injected into the oscillator cavity of the diode laser, and the coupling efficiency of the laser into the RDC is significantly enhanced due to the FOF effect. An optical component having parallel optical surfaces is inserted exactly normal to the light beam in the RDC. The optical losses of the component are obtained from the change in the ring-down time of the RDC containing the component with respect to that of the empty RDC. The measurement results for different samples are in good agreement with conventional laser calorimetry data. The experimental results have demonstrated that the FOF-CRD technique is simple, inexpensive and fast for measuring optical losses of optical components used in high-power laser system.