الفهرس 
RANDOM FIBER LASER SYSTEM REVIEW
Gain Mechanisms in RFLOnly 14 pages are availabe for public view
 |  | from | 157 |  |  |
| | | from | 157 | | |
Abstract
In this thesis we report a broadband tunable random fiber laser with ultra narrow line-width single longitudinal mode (SLM), based on Rayleigh backscattering in standard single mode fiber (SMF). The wide tuning range of this SLM fiber based laser over 1500 nm – 1570 nm is demonstrated for the first time to the best of our knowledge, with a line-width of 4.5–30 kHz. The tuning is achieved using a tunable bandpass Fabry–Perot filter, and a semiconductor optical amplifier (SOA) is used as the wide-bandwidth gain medium in a linear cavity configuration. A numerical model is also developed accessing the random Rayleigh backscattering throughout the fiber length, and solving the transient time domain SOA rate equations. The model accounts for the dynamics of the SLM random laser building up from transient regime to saturation regime.
We employed the implemented SLM random fiber laser as the core structure to configure a novel tunable dual-wavelength random fiber laser in the C-band with ultra-narrow line-widths. Single longitudinal mode dual wavelengths random fiber laser of tunable separation in range 1.5 – 25 nm (187.5 GHz – 3.12 THz) is presented. In the laser configuration a standard single mode fiber of 2 km length is incorporated as distributed mirrors. Two optical bandpass filters are used for the wavelength selectivity, and two Faraday rotator mirrors are used to stabilize the two lasing wavelengths against fiber random birefringence. The optical signal to noise ratio (OSNR) was measured to be 38 dB. The line-width of the laser was measured to be in range 3 – 11.5 kHz, at different wavelength separations and different SOA pump currents.
We presented another novel tunable dual-wavelength random fiber laser configuration in the C-band with narrower line-widths 2.6 – 3.1 kHz at dual wavelength of 14 nm separation (1550 – 1564 nm). In this configuration, the laser action is contingent on Rayleigh backscattering phenomenon in a single mode fiber of 1 km length, and an Erbium Doped Fiber amplifier (EDFA) for optical amplification. The optical signal to noise ratio (OSNR) is 44 dB. Then a comparison between the results of the two configurations is performed.