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28 January 2002 Development of a high total radiation dose-resistant vertical-cavity surface-emitting laser driver with discrete COTS components
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Radiation tolerant fiber optic transmission links are desired for their potential use in future thermonuclear fusion reactors and other harsh radiation fields. As part of it, we design and test a radiation opto-electronic transmitter based on vertical-cavity surface-emitting lasers (VCSELs) and dedicated driver electronics consisting of discrete components. VCSELs have already demonstrated their high radiation acceptance level. We confirm this by on-line irradiation experiments on such devices up to 10 MGy total dose. For the design of the driver circuit, we rely on discrete commercial-off-the-shelf (COTS) bipolar transistors. When the radiation induced degradation of these components is considered within the time design of the circuits, total dose levels larger than 1 MGy can be tolerated. The driver uses standard TTL input signals and delivers a forward current of 12 mA to a pigtailed 840 nm VCSEL. SPICE simulations show that the driver still delivers a sufficient forward current to the VCSEL, in spite of the radiation induced degradation of the Hfe and VCEsat values of the transistors. These simulations are verified by our experiments. At a total dose of 1 MGy, the measured decrease of the forward current is only about 8%. This induces an optical output power decrease that can still be tolerated with irradiated VCSELs, as shown by our experiments. We conclude that a high total dose hardened optical transmitter for use in nuclear instrumentation systems can be fabricated using discrete COTS bipolar transistors, COTS vertical-cavity surface-emitting lasers and COTS optical fiber.
© (2002) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Marco Van Uffelen, Kathleen Embrechts, Francis Berghmans, Simon Coenen, Marc C. Decreton, and Juergen Van Gorp "Development of a high total radiation dose-resistant vertical-cavity surface-emitting laser driver with discrete COTS components", Proc. SPIE 4547, Photonics for Space and Radiation Environments II, (28 January 2002);

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