Patent ID: 8885167
Filing Date: 2014-11-11
Classification: G01N,H01S

Abstract:
1. A method of measuring cavity loss of a resonant optical cavity over a range of frequencies by exciting one or a plurality of cavity modes of the cavity in a controlled manner, the cavity having at least two cavity mirrors, one of which is a cavity coupling mirror, using a laser that emits continuous wave laser light, wherein the laser is responsive to optical feedback light emerging from the cavity, and wherein a mean optical frequency of the laser is adjustable over a range of frequencies, the method comprising: coupling the laser light to the cavity via the cavity coupling mirror using mode matching optics, the cavity having a plurality of optical resonance cavity modes that have frequencies within said range of frequencies of the laser; applying to the laser a drive current comprising a series of current pulses, each having a predetermined current profile, so as to adjust the mean optical frequency of the laser and to excite desired cavity modes in an order as determined based on the shape of the applied current pulses; and detecting dynamics of the intra cavity optical power of light circulating in the cavity after a cavity mode has been excited, wherein an end portion of one current pulse sets the laser drive current below a laser threshold value, wherein the current profile of the next current pulse applied to the laser includes a compensation pulse portion that drives the laser at a current level and for a duration sufficient to compensate for some or all of the laser heat lost while the laser drive current was below the laser threshold value and to excite the next mode in said order.