Remote Sensing with Use of Coherent Parametric Quantum Amplifiers

Optical amplifiers play a key role in a variety of optical communication and sensing applications. Their value in direct detection is in overcoming the thermal noise of the detector which can lead to significant improvements in sensitivity. However, even highly sensitive coherent detection can benefit from amplifiers that help to overcome loss and detector inefficiencies thereby improving sensitivity. While almost all optical amplifiers in use are of the phase-insensitive type, which must add noise due to quantum mechanical constraints, phase sensitive amplifiers can be nearly noise-less. Significant strides have recently been made in using phase sensitive amplifiers to realize highly sensitive receivers for use in communication applications. We consider the issues and advantages of using such amplifiers for applications in sensing.