Accession Number : ADP008223

Title :   Polarization Mode Locking in Erbium Doped Fiber Ring Lasers,

Corporate Author : FONDAZIONE UGO BORDONI ROME (ITALY)

Personal Author(s) : Romagnoli, M. ; Tajani, A. ; Tamburrini, M. ; Wabnitz, S. ; Daino, B.

Report Date : APR 1992

Pagination or Media Count : 4

Abstract : Mode-locking (ML) with erbium doped fiber lasers permits to combine the wide spectral bandwidth of the gain medium with the anomalous group velocity dispersion of the fiber. As a result, soliton pulse shaping plays a key role in the ML dynamics. By combining ultrashort soliton amplification and soliton switching, it has been demonstrated that ML erbium doped fiber lasers may operate in the femtosecond regime. These ML sources are intrinsically self-starting and unstable, and the origin of the observed complex temporal behavior has been recently ascribed to soliton resonances with the laser cavity length. In this work we present results of experimental studies of the role of polarization rotation as a switching mechanism in both active and passive ML in erbium doped fiber ring lasers. In the active case, by controlling the state of polarization we observed the generation of ML 100 femtosecond pulse trains, with repetition rates as high as 300 GHz. In the passive case, ML is self-starting and we observed the generation of multiple pulses with different wavelengths and polarization states. Here the control of the state of polarization permits the selection of the output wavelengths. The experimental configurations for active and passive ML in erbium doped fiber ring lasers are shown. In both cases, gain is provided by a 10 m long erbium doped fiber (aluminium codoped), with the numerical aperture NA = 0.2, and the absorption of 5.5 dB/m at the wavelength lambda = 1532 nm.

Descriptors :   *POLARIZATION, *RING LASERS, *OPTICAL SWITCHING, ABSORPTION, AMPLIFICATION, APERTURES, BANDWIDTH, CONFIGURATIONS, DISPERSIONS, DYNAMICS, ERBIUM, GAIN, GROUP VELOCITY, LASER CAVITIES, NUMERICAL APERTURE, OUTPUT, PULSE TRAINS, PULSES, REPETITION RATE, ROTATION, SELECTION, SOLITONS, VELOCITY, MODE LOCKED LASERS, GLASS FIBERS, ITALY.

Subject Categories : Optics
      Lasers and Masers

Distribution Statement : APPROVED FOR PUBLIC RELEASE