SBIR-STTR Award

Depending on the particulars of an engagement scenario, doppler shifts due to the relative motion of a missile and a sensor platform can be in excess of 1000 MHz for a coherent COE2 sensor system. Since the response of the sensor's heterodyne detector can be degraded by as much as 50% at these large offset frequencies, a local oscillator capable of being tuned either up or down 1000 MHz to compensate for this relative motion would be equivalent to increasing the sensor's laser transmitter power by a factor of two. Because a coherent COE2 sensor system already has a LO, any improvement in system performance afforded by an improved LO would be accomplished without altering the system weight, size or power budget. Two separate innovations, one in resonator design and another in discharge excitation are proposed to achieve a Phase I goal of 100 mW of sealed-off cw laser output power at 1500 MHz from laser line center.

The response of a sensor's heterodyne detector can be degraded by as much as half at these large offset frequencies, a local oscillator capable of being tuned either up or down 1000 MHz to compensate for this relative motion would be equivalent to doubling the sensor's laser transmitter. Such an improved system performance will be achieved with a negligible change in the system's weight, size or power budget since an local oscillator is already required. Two swept cavity configurations of the Phase I device generated tuning ranges of 1250 and 1950 MHz and over 2 watts of cw power on laser line center was extracted from an 8.6 cm length of sealed-off C02 medium. Two Phase II lasers with tuning range/power goals of 2000 MHz/ > 2W and 2500 MHz/>SW are proposed. The Phase I method of inferring the tuning range by sweeping over the cavity FSR will be combined with heterodyning the output of each laser with a reference laser. Benefits include a global wind sensor in a low earth orbit, a commercially available, sealed-off, wideband tunable C02 local oscillator for use in wideband detector evaluation and high resolution IR spectroscopy and a new means for stabilizing a C02 laser.