Manipulation on infrared-single-photon by frequency upconversion

The tunability of the two photon absorption coefficient (TPAC) is studied in the HgCdTe p-n junction with the external bias voltage. The TPAC in the p-n junction region will strongly manipulated by the build-in field induced Franz- Keldysh (F-K) effect on the energy band structure. The obvious two photon absorption process is clearly observed as the nonlinear enhancement of photo-voltage on the incident light intensity in the power of 2. The maximum enhancement factor of the TPAC has been achieved as high as 12 times. It can be very useful for the nonlinear optical device.