GRIN Lens Coupled Top-Illuminated Highly Linear InGaAs Photodiodes

We report a graded index (GRIN) lens-coupled highly linear InGaAs photodiode with a third-order harmonic output intercept point of 54 dBm and an estimated third output intercept point of 49.2 dBm. Optical beam shaping through GRIN lens coupling enhances the third-order intercept by 8 dB as compared to single-mode fiber coupled photodiodes.