Nonlinear Generation Of High Power Millimeter Wave Optical Intensity Modulation

Abstract

Practical methods to generate high power, optical intensity modulation, from a laser diode, at mm wave frequencies may be useful for a number of optical transmission, radar, signal processing, or component testing applications. While source bandwidths exceeding 20 GHz have been achieved by direct modulation of diode lasers[1], or by using external waveguide modulators[2], in general these devices fall short of the region between 30 and 100 GHz, which is of some interest. In this paper we discuss an interferometric method, the FM sideband technique, which has the following important features: 1 - intensity modulation from a laser diode is generated at frequencies which are much greater than the direct modulation bandwidth of the laser diode, 2 - the maximum frequency response is limited by detector rather than source bandwidth and, 3 - this technique is extremely efficient (in may cases, it is more efficient than direct modulation of a laser diode), and thus can generate signals with high power. Using the FM sideband technique a 40 GHz optical carrier signal has been generated by direct modulation of a laser diode at 13 GHz. While the maximum frequency we could observe was limited by the availability of high frequency measurement electronics, frequencies on the order of 100 GHz should be obtainable using suitable detectors[3,4]. We have also demonstrated upconversion of a narrow band baseband information channel to a 11 GHz carrier, and high frequency detector characterization using the FM sideband technique[5].