Design, optical and high frequency characteristics of double stage tapered photodiodes for >40Gb/s applications

Evanescently-coupled photodiodes, integrating double stage taper, have been realized for low cost, high-speed, and high power applications. 50 GHz bandwidth and more over +14 dBm optical power, have been achieved at -3 V bias with 0.8 V output voltage. 0.5 A/W responsivity has been measured for a 25 /spl mu/m long diodes. Polarization dependence is as low as /spl plusmn/0.1 dB. These diodes are suitable for future 40 Gbit/s and radio over fiber applications.