Abstract

Frequency conversion of optical data signals is a key operation of switching nodes in coherent optical multicarrier systems. All-optical methods for frequency conversion are four-wave mixing in semiconductor laser optical amplifiers^1,2 and light injection in distributed-feedback lasers³ and in multisection lasers.⁴ We report here on experimental and theoretical work on frequency conversion by nearly degenrate four-wave mixing in traveling-wave semiconductor laser amplifiers. The frequency conversion rate is limited by the gain-bandwidth product of the amplifier, which is about 4000 GHz in the work discussed here. In general, the conversion efficiency is larger than 1 because of the interna1 gain of the amplifier. The dynamic range for the input signal power exceeds three orders of magnitude. Moreover, an optical data signal can be converted simultaneously to several (for instances, 10) different frequencies by suing only one semiconductor laser amplifier. The frequency converter operates on data signals up to 1 Gb/s independent of modulation scheme and bit rate. It can be advantageiously applied to angle modultation schemes. Disadvantages of the considered frequency converter are the requirements of stable and narrow-linewidth lasers to avoid the accumulation of phase noise.

© 1991 Optical Society of America