We present the fs laser inscription of ring-shaped random structures using Spatial Light Modulator (SLM) in multimode GRIN fiber. The use of SLM allows one to modulate the phase of the fs radiation incident on it and to write various structures with complex geometries inside the static fiber core. We optimized the fs laser inscription parameters: pulse energy, SLM frame rate, overall length and distances along the fiber of the structures to enhance Rayleigh backscattering level at minimal insertion losses. In particular, scattering structures with random distances along the fiber were written using the Line-by-Line method in single mode fiber at the optimal inscription parameters (pulse energy of 3 μJ, SLM frame rate of 5 Hz, the overall of 2 mm and random distances along the fiber in the range of 5 μm). Further, we created the ring-shaped random structures in 100/140 μm GRIN multimode fiber with enhanced Rayleigh backscattering level by +66 dB/mm relative to the intrinsic fiber level. Owing to the variation of random distances along the fiber and ring’s diameters of structures in range of 0.5 μm and 20 μm, respectively, allows one to obtain a broadband reflection spectrum within 88 nm with a reflection coefficient of 0.01%. The low threshold generation with ring-shaped output beam of the Raman fiber laser with random distributed feedback based on the SLM-inscribed random structures in the multimode fiber is demonstrated for the first time.
Linear and non-linear propagation of ultrashort pulses in a seven-core fiber was investigated experimentally and numerically in a normal dispersion regime. We observed non-uniform coupling conditions between different cores that may be the result of a random refractive index deviation. It was characterized by measurements of the power distribution and FROG traces at the output of a multicore fiber. The cores were excited by a spatial light modulator using the weighted Gerchberg-Saxton algorithm to generate phase masks. It allows us to switch-on any combination without manual alignment of the experimental setup. Finally, as the input power increased, a nonlinear coupling was observed between the selected cores, similar to a saturable absorber. So we believe that such a device could be useful for a development of high-power ultrashort fiber lasers and pulse shaping applications.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.