Abstract

Semiconductor optical amplifiers (SOAs) have been investigated for linear in-line amplification in several wavelength division multiplexed (WDM) system demonstrations^1–3 at speeds up to 20 Gb/s. More recently, a new type of semiconductor amplifier was demonstrated⁴ which has unique properties for linear amplification. However, there are limitations associated with all the above approaches. It is therefore of interest to investigate in detail the performance of different types of SOAs for linear amplification and understand the limitations in a more quantitative manner. This is particularly true in the case of applications at 40 Gb/s, where there are issues related to high transmitter losses as well as short pulses carrying data. The loss due to data generation could be as large as 19–20 dB (bringing the output power down to –10 dBm) which needs to be made up by amplification. One may amplify the signal with an erbium doped fiber amplifier (EDFA) after multiplexing the different wavelengths. One can also amplify each wavelength independently with a SOA. This method enables signal level equalization before transmission by adjusting each SOA’s gain. In addition, SOAs offer the possibility to be monolithically integrated together with the multiplexer (MUX) on the same chip.

© 2002 Optical Society of America