4/27 Radiation Effects in Active Optical Components Robert A. Reed, Ken LaBel, Janet Barth, Henning Leidecker, Allan Johnston, Paul Marshall and Cheryl Marshall

4/27 Radiation Effects and Analysis Group

4/27 Outline Introduction to radiation effects in optical components Radiation environment optical components Radiation induced transients in optical components Radiation induced degradation mechanisms in optical components Summary

4/27 Radiation-Induced Effects in Optical Components (ns) (V) Single Event Transient x10 10 Fluence (p/cm 2 ) CTR 8x x10 10 Displacement Damage Dose (kRad(Si)) I-lite (mA) Total Ionizing Dose

4/27 Radiation Environments Heavy Ion LET Spectra Total Ionizing Dose Proton Spectra

4/27 Heavy Ion

4/27 Total Ionizing Dose

4/27 Proton Environment

4/27 Equivalent Proton Fluence for Displacement Damage

4/27 Active Optical Components Optical coupling of two electrical circuits with an optical transmitter and an optical receiver. –LEDs, Phototransistors, photodiodes, etc... Optocoupler is one type of optical components –CTR = I o/ I f LED DETECTOR

4/27 Radiation-Induced Effects in Optical Components (ns) (V) Single Event Transient x10 10 Fluence (p/cm 2 ) CTR 8x x10 10 Displacement Damage Dose (kRad(Si)) I-lite (mA) Total Ionizing Dose

4/27 A sample SET from an HP QCPL-6731 Optocoupler Single event transients induced in photodetector can be passed to circuitry that follows the optocoupler if the amplification stage recognizes the SET as a valid signal

4/27 Ground Based Single Event Transient Measurements

4/27 Radiation-Induced Effects in Optical Components (ns) (V) Single Event Transient x10 10 Fluence (p/cm 2 ) CTR 8x x10 10 Displacement Damage Dose (kRad(Si)) I-lite (mA) Total Ionizing Dose

4/27 Total Ionizing Dose Degradation of Phototransistor

4/27 Total Ionizing Dose Degradation of LED

4/27 Radiation-Induced Effects in Optical Components (ns) (V) Single Event Transient x10 10 Fluence (p/cm 2 ) CTR 8x x10 10 Displacement Damage Dose (kRad(Si)) I-lite (mA) Total Ionizing Dose

4/27 Optocoupler Current Transfer Ratio Degradation with Proton Fluence

4/27 DC/DC Power Converter that Contains an Optocoupler

4/27 LED Data from the Early 80’s

4/27 Various Optocoupler Results

4/27 Observed Properties of a “good” optocouplers Single Event Transient –Observed in devices that operate at > 5MhZ –Circuit filtering is possible Total Ionizing Dose –Shielding may help reduce TID (WARNING) Displacement Damage –Not Amphoterically doped –LED wavelength <800nm –Maximize LED drive (WARNING) –Operation of phototransistor in saturation RADIATION RESPONSE IS KNOWN

4/27 SUMMARY Evaluation of three radiation induced effects is important for optical components links –SET, TID and Displacement Damage Unable to predict radiation response from manufacture information Data is available on some optical components Radiation testing at off site proton facility –Simultaneous evaluation of SET, TID and Displacement Damage Some optical components perform very well in the space radiation environment