Group delay and α-parameter measurement of 1.3 μm semiconductor traveling-wave optical amplifier using the interferometric method

The group delay dispersion and the linewidth broadening factor (α-parameter) are measured for a 1.3-μm semiconductor traveling-wave optical amplifier (TWA) using a newly developed interferometric method. By Fourier transforming an interferometric cross-correlation signal, both the optical phase and the gain are simultaneously obtained in the entire gain bandwidth. The group delay spectrum is evaluated from the frequency derivative of the phase, and by selecting an appropriate interval for the interferometer scan, a refractive index dispersion of ~ 3.2 fs/nm is separated from the dispersion caused by Fabry-Perot resonance. From the phase and gain change with injection current, the α-parameter spectrum is evaluated, and the results indicate a strong dependence on wavelength