Application of near-field optical-fiber probes to millimeter-wave optical heterodyne

• Published in: IEEE transactions on microwave theory and techniques Vol. 47; no. 7; pp. 1381 - 1384
• Main Authors: Seok Kil Han, Ali, M.E., Sang-Dong Jung, Kwang-Yong Kang, Fetterman, H.R.
• Format: Journal Article
• Language: English
• Published: IEEE 01.07.1999
• Subjects: Beams (radiation); Devices; Fiber optics; Heterojunction bipolar transistors; High speed; High speed optical techniques; Microwaves; Millimeter wave measurements; Millimeter wave technology; Millimeter wave transistors; Noise levels; Optical beams; Optical devices; Optical fiber devices; Optical fibers; Optical mixing; Probes; Ultrafast optics
• ISSN: 0018-9480; 1557-9670
• DOI: 10.1109/22.775482

We demonstrate the use of near-field fiber-optic probes in optical heterodyne characterization of high-speed devices. The submicrometer-size optical beam obtained from the fiber-optic probe was employed to selectively excite a tiny area of the device active region. Optical heterodyne measurements on heterojunction bipolar transistors were conducted at 1.3 /spl mu/m with a difference frequency of 60 GHz. Significant response of the device with a signal-to-noise ratio of 25 dB was observed. The dc and ac photoresponse was also measured as a function of the distance between the fiber probe and the device-under-test. The data clearly showed distinguishable regimes of near- and far-field operation. The near-field high-frequency optical heterodyne technique as explored in this paper provides us with new capabilities that can be effectively utilized in the field of optical millimeter-wave interaction in ultrafast devices.