DARPA and the aPROPOS program

DARPA has in place the Advanced Precision Optical Oscillator (APROPOS) program to support the development of new, high-spectral purity optical oscillators. In addition to the promise of low phase noise, optical oscillators are developed to meet the challenge of reliability, tunability, and spectral purity under vibration and acceleration. The DOD and many industries acutely recognize the need to synthesize multiple frequencies that are generated with low phase noise and low frequency instability. Also, there is a strong need for reduced sensitivity of these frequencies to acceleration and vibration, but there is little current research addressing this challenge. While there are numerous efforts to significantly reduce the quiescent random phase noise of oscillators operating at microwave frequencies, few projects address the critical need for tunability and low acceleration and vibration sensitivity in these oscillators. Both efforts are essential if these oscillators are to achieve wide usage in field applications.