Demonstration of the high-frequency optical heterodyne technology using near-field fiber-optic probes

Abstract

We demonstrate the use of near-field fiber-optic probes in optical heterodyne characterization of high-speed devices. The submicron-size optical beam obtained from the fiber-optic probe was employed to selectively excite a small local portion of the active region of the device. Optical heterodyne measurements on heterojunction bipolar transistors were conducted at 1550 nm with a difference frequency of 100 GHz. The significant response of the device with a signal-to-noise ratio of 30 dB was observed. The dc and the ac photoresponses were also measured as a function of the distance between the fiber-optic probe and the device under test. The data showed clearly distinguishable regimes of near- and far-field operation. The high-frequency near-field optical heterodyne technique as explored in this letter provides us with capabilities that can be effectively utilized in the field of optical millimeter-wave interaction in ultrafast devices.