Thermo-optic coefficient of silicon at 1550nm and cryogenic temperatures

The thermo-optic coefficient dn/dT of silicon was measured at 1550nm in the wide temperature range from 5K to 300 K. For this purpose an interferometric measurement scheme was applied using the silicon sample as a Fabry-Perot etalon. The high resolution of this setup revealed a thermo-optic coefficient as low as 10(-8) K-1 at 5K. The presented results show an excellent agreement with former measurements above 30K including a value of dn/dT = 1.8 x 10(-4) K-1 at 300K. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4738989]