Radiation resistance of a Mach-Zehnder optomodulator for analog signal transmission

We have been pursuing the possibility of using Mach-Zehnder type optomodulators for analog signal transmission, especially for high energy physics experiment applications. Since they will be placed in a rather high radiation area, radiation resistance is one of the essential properties it should have. As part of the test in developing the device, we did a radiation resistance measurement using a cobalt 60 source on some of the units we have. The optomodulator was keep functioning after total of 10 Mrads gamma ray irradiation. Similar tests on optical cement and optical fibers were also performed.