All-fiber spectrometer for the determination of the emission wavelengths of semiconductor lasers

Abstract

An all-fiber spectrometer is described for measurements of the emission wavelengths and the spectral linewidths of semiconductor lasers in the spectral region between 1100 and 1700 nm. These lasers are used as radiation sources in the optical communication technique. The basis of this measuring procedure is the determination of the group delay of optical pulses emitted by the laser under test. In order to cover the above mentioned spectral range, two single-mode fibers are employed, a standard and a dispersion shifted fiber. The measurements are compared with test results with the aid of a grating monochromator. The agreement is very satisfactory. The accuracy depends on several parameters, for example, on the fiber length, but in general, about ±1 nm is achievable.