Experimental and Theoretical Linearity Investigation of High-Power Unitraveling-Carrier Photodiodes

In this letter, the third-order intermodulation distortion of a high-power InGaAs-InP unitraveling-carrier photodiode is examined. Based on experimental data, we have developed an analytical model using a harmonic balance method. The response-time reduction, under high-current operation, is identified as the main nonlinear mechanism before saturation occurss. In addition, a linearity enhancement with increased photocurrent (up to ~40 mA) is observed and analyzed. This leads to a measured third-order intercept point, at 40-50 mA, as high as 32 and 37 dBm at 20 and 5 GHz, respectively.