OPTICAL FRONT END FOR A RADIO RECEIVER

OPTRA proposes to investigate the sesign of an optical front end for a receiver that converts ultra wide dynamic range, broadband, VLF to HF radio signals into a digital representation and with no loss of significance or resolution. Essential elements of the design are 1) an integrated optical waveguide phase modulator that imparts a phase modulation on an optical beam for a CD type laser diode, a process that is strictly linear with the received signal and 2) an optical process homodyne interferometer and high speed digital phase processor that recovers the phase modulation with shot noise limited sensitivity as a 32 bit wide digital words for subsequent processing by a Digital Signal Processing (DSP) chip based signal processor. An attendant benefit of the optical front end is that it can be remote, e.g., at the antenna site, from the signal processing section through use of low loss, EMI proof optical fibers. In this case, since there are not electrcial signals present at the antenna, e.g., L.O. leakage, it would also be inherently secure.