The anomalous injection locking of a traveling-wave semiconductor optical amplifier (SOA) and a fiber-pigtailed Fabry-Perot laser diode (FPLD) linked with single-mode and improved side-mode suppression ratio output is demonstrated. We achieve this injection locking by driving the FPLD slightly below threshold and by feedback injecting the FPLD with fractional output of a closed-loop SOA. The SOA-FPLD link lases in a single FPLD longitudinal mode with a reduced linewidth of 0.013 nm and a maximum side-mode-suppressing ratio of 39.7 dB. A precise 3-dB linewidth of 45–50 MHz is also observed from the self-homodyne mode-beating spectrum. The optimized feedback-injecting power for the FPLD is ~2% of the SOA-FPLD linked output power of >400 μW. The variations in output power and in peak wavelength are not more than 0.54% and 0.06%, respectively. The injection-locked SOA-FPLD link is insensitive to the temperature fluctuation within ±0.25 °C.
© 2004 Optical Society of America
Gong-Ru Lin and Pai-Shen Hsueh, "Spectral Characteristics of a Regenerative Semiconductor Optical Amplifier Mutually Injection Locked with a Fabry-Perot Laser Diode," Appl. Opt. 43, 153-159 (2004)