Abstract

Stimulated Brillouin scattering (SBS) typically limits the launch power for a data-encoded signal to the range of 9 dBm to 10 dBm. In order to exceed this level for applications requiring high launch powers, such as repeaterless transmission systems,¹ the spectrum must be artificially broadened. Severa1 methods for broadening the spectrum have been reported. Small-signal direct modulation is an attractive approach for modest increases in the SBS threshold². However, it suffers from significant residual amplitude modulation (AM) when large thresholds are required. External phase modulation provides any desired broadening with negligible residual AM at the expense of a phase modulators³. In this paper, we report on an efficient method for suppressing the SBS with negligible residual AM using the temperature tunable properties of a semiconductor laser diode. Here, we demonstrate an effective threshold of 23.4 dBm by applying a 16 V_pp, 5 kHz sinusoid to a thin-film resistor on top of the laser diode. The residual AM is measured to be only 1.2·10⁻⁴.

© 1996 Optical Society of America