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Masaki HIRANO Ryosuke YOTSUTANI Akihiro MORIMOTO
We obtained flat optical frequency combs by using the FM laser operation of a fiber ring laser and external intensity modulation. Extremely wide FM spectra can be easily obtained by the moderate internal phase modulation of an FM laser. We used an external intensity modulator to extract a linearly chirped part from the FM light in order to obtain flat spectra. In our experiments, we obtained a flat optical frequency comb with a spectral bandwidth of about 0.5 THz and a power deviation of less than 1.5 dB.
The thermal and/or the tensile strain distribution along the fiber make the Brillouin gain coefficient different in each point of the fiber. As a basic study of the Brillouin fiber optic gyro, its effect on lasing characteristics of a fiber Brillouin ring laser is formulated in the general form by using the statistical function and then calculation is done for typical values of the parameters. By suppressing the polarization-fluctuation-induced noise caused by the temperature, an example of the effect of the spatially distributed gain coefficient is experimentally demonstrated.