High-sensitivity semiconductor optically preamplified 25 GHz receiver

High-sensitivity, high-speed optical receivers are important components for both high-bit rate and microwave modulated optical systems. Optically preamplified receivers circumvent the gain-bandwidth limitation of APD receivers and have demonstrated improved receiver sensitivity in optical fiber systems at data rates up to 10 Gbit/s. In order to obtain maximum sensitivity, an optically preamplified receiver must be optical amplifier noise limited rather than thermal noise limited. Operation in this regime is more difficult to achieve at higher frequencies, however, due to reduced detector quantum efficiency and higher electronic receiver noise. We demonstrate an optically preamplified receiver comprised of a semiconductor optical amplifier (SOA) and 25 GHz Schottky InGaAs photodiode operating at the SOA noise limit. Because of the broadband, low-responsivity of this photodiode, these results apply over its entire spectral range (400-1600 nm), subject to SOA availability, as well as to operation at frequencies up to 120 GHz.