title: OSNR monitoring technique based on cascaded long-period fiber grating with optically tunable phase shifter.
abstract: An optical signal-to-noise ratio (OSNR) monitoring technique using a cascaded long-period fiber grating with a tunable phase shifter is proposed for non return-to-zero on-off-keying (NRZ-OOK) and differential phase shift keying (DPSK) signals. This method is based on two key points: first, the cascaded long period fiber grating (CLPG) acts as an optical delay interferometer (ODI) by Mach-Zehnder configuration consisting of the core and cladding modes inside the CLPG. Secondly, an optically tunable phase shifter using an Yb(3+) doped optical fiber (YDF) is inserted between the CLPG. The phase of the modulated signal propagating along the core mode of YDF is controlled by adjusting pumping power of 976-nm laser diode (LD). By combining the CLPG with the optically tunable phase shifter, the OSNR monitoring could be successfully executed.
authors.affiliation: Department of Information and Communications, Gwangju Institute of Science and Technology, Gwangju 500-712, Republic of Korea.
authors.forename: Sie-Wook
authors.initials: SW
authors.lastname: Jeon
authors.forename: Young Ho
authors.initials: YH
authors.lastname: Kim
authors.forename: Byeong Ha
authors.initials: BH
authors.lastname: Lee
authors.forename: Min A
authors.initials: MA
authors.lastname: Jung
authors.forename: Chang-Soo
authors.initials: CS
authors.lastname: Park
mesh_terms: D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005374:Filtration / Q000295:instrumentation*; D008027:Light; D008962:Models, Theoretical; D055100:Optical Fibers; D012031:Refractometry / Q000295:instrumentation*; D012542:Scattering, Radiation; D013685:Telecommunications / Q000295:instrumentation*