Abstract: The apparatus is a miniature assembly which detects very low power infrared radiation and produces an electronic signal. The incoming infrared is combined in a wavelength multiplexer with high energy light from a laser chip and passed through an upconversion crystal (a nonlinear optical crystal) in which their frequencies are added together. The higher frequency, lower wavelength, light is then directed to a miniature blue sensitive photomultiplier tube that generates an electrical signal. A thermoelectric cooler is used to control the temperature of the laser chip, and the entire device is assembled into a package which is approximately the size of a cigarette pack.

Abstract: Optical devices using non-centric crystals, such as lithium niobate, and methods for making and using the devices, are provided. The devices provide improved temperature stability as compared to conventional devices using non-centric crystals. The improved temperature stability is provided by etching the surface of a non-centric crystal to a depth of less than about 300 angstroms. The devices and methods of the invention reduce the magnitude of change in bias voltage required to maintain an optical crystal at a pre-selected operating point.