Application of COTS high-power laser diodes and driver for a free-space laser communication terminal

摘要

Abstract: Recently, there has been strong interest in theapplication of commercial-off-the-shelf (COTS)electronic and optoelectronic (O/E) components for freespace laser communication application. Besides thespace qualified packaging issues, the main problems ofusing COTS O/E transmitter are: (1) Telecom grade lasertransmitters do not have sufficient power to meet thefree space laser communication requirements; (2) COTSlaser diode transmitter driver circuits have limitedpeak drive current, usually below 100 mA, which is toolow for driving high power laser diodes; and (3) COTShigh power laser diodes are usually not used for highdata rate applications since the high speed performanceof the laser/driver combination is usually inadequate.In this paper we will present our latest study resultson the SDL 5430 and SDL 580 high power laser diodesdriven by high current laser drivers at data rates from600 Mb/s to over 1 Gb/s. Several models from the HY6000family of high current and high speed laser diodedrivers from Hytek Microsystems Inc., designed for freespace laser communication applications, have beentested with the SDL high power laser diodes. Usingdirect drive technique with NRZ modulation, averageoutput power over 100 mW at 622 Mb/s were obtained withthese low cost Hytek drivers. For data rates over 1Gb/s, the parasitic associated with the laser diodebecomes an important limitation factor. We havemeasured the capacitance of the SDL 5430 and the newjunction up SDL 580 laser diodes, an equivalent circuitmodel is developed to examine the effect of theseparasitics on the speed of the laser diode. The resultsare consistent with our experimental observations. !5