An erbium-doped fiber laser that produces a train of intense noiselike pulses with a broadband spectrum and a short coherence length is reported. The noiselike behavior was observed in the amplitude as well as in the phase of the pulses. The maximum spectral width obtained was 44 nm. The high intensity and the short coherence length of the light were maintained even after propagation through a long dispersive fiber. A theoretical model indicates that this mode of operation can be explained by the internal birefringence of the laser cavity combined with a nonlinear transmission element and the gain response of the fiber amplifier.

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Noiselike pulses with a broadband spectrum generated from an erbium-doped fiber laser.

Simultaneous continuous wave multiwavelength operation of an erbium-doped fiber laser has been demonstrated using two types of recently developed in-fiber grating comb filters. The lasing wavelengths and linewidths were determined by the comb filter, which was inserted in a ring cavity with a single inhomogeneously broadened gain medium.

Multiwavelength generation in an erbium-doped fiber laser using in-fiber comb filters

A novel multiwavelength fibre laser is proposed, which is based on a fibre loop mirror formed by a high-birefringence (HiBi) fibre, a polarisation controller, and a directional coupler By setting the polarisation controller properly, the HiBi fibre loop mirror acts as a polarisation-independent wavelength filter With this configuration, the wavelength spacing of the laser can be varied accurately by adjusting the length of the HiBi fibre Experimentally, by cooling the erbium-doped fibre with liquid nitrogen to reduce its homogeneous linewidth, stable emission at 16 wavelengths with a spacing of 08 nm and an amplitude variation of < 5 dB was achieved

Multiwavelength erbium-doped fibre laser based on a high-birefringence fibre loop mirror

We have demonstrated a novel approach to obtain a 0.1-nm line width laser with 38-dB sidemode suppression by utilizing a 1.3-/spl mu/m semiconductor optical amplifier in a fiber unidirectional ring that consists of a linear polarizer and polarization controllers. The laser has a low-threshold current of 22.5 mA as well as a wide tuning range of 28 nm. The new approach is applicable to the 1.55-/spl mu/m region as well. It is expected that nanosecond wavelength tuning speed is feasible using this approach in conjunction with fast electrooptic polarization controllers, short cavities and low-cavity losses.

A widely tunable narrow linewidth semiconductor fiber ring laser

The polarization properties of single-mode optical fibers are theoretically modeled with use of the Jones formalism. The fiber is described as an elliptical birefringent plate. The properties predicted by this model are discussed and lead to the development of a simple experimental method to extract the parameters that describe a real fiber. A magneto-optic method that measures the beat length of the fiber is also presented and gives a more complete description of the fiber. The validity of the model is then clearly established. Finally, the wavelength dependence of the parameters characteristic of the fiber is experimentally investigated.

Measurement of the elliptical birefringence of single-mode optical fibers.

When an intracavity polarizer is introduced into a Fabry-Perot Nd-doped fiber laser, wide wavelength tunability is achieved either by rotating the polarizer or by varying, the fiber birefringence with an in-line polarization controller. The intracavity polariser also produces considerable line-narrowing. A model based on birefringence dispersion is proposed. >

https://www.eng.tau.ac.il/~tur/pdfs/64.pdf

Wavelength tunability in a Nd-doped fiber laser with an intracavity polarizer

An unpolarized comb-like spectrum is emitted from a fiber laser constructed from a Nd-doped silica fiber connected to an undoped high-birefringence fiber. Depending on the overall birefringence of the high-birefringence fiber, spectral spacings of 0.8 nm to 4 nm between two adjacent wavelengths were obtained, with as many as eight simultaneous discrete peaks. No intracavity polarizing elements were used, and the observed spectral characteristics are due to parasitic reflections at the interface between the two fibers. >

A fiber laser with a comb-like spectrum

Polarization related phenomena in Nd-doped fiber lasers

Introducing an intracavity polarizer into a Fabry-Perot, birefringent, Nd-doped fiber laser, produces a fundamental change in the laser spectrum. The change is a consequence of the wavelength dependent loss which is inflicted by the polarizer. In two set-ups described, tuning and a comb-like spectrum are easily produced.

Wavelength control in fiber lasers

A ring-type fiber laser with an external birefringent Bragg grating reflector is presented. The birefringent grating has a polarization-dependent transmission/reflection spectrum and by adjusting an intracavity polarization controller, a tunability range of 0.6 nm is achieved.

Uri Ghera

Papers

Wavelength tunability in a Nd-doped fiber laser with an intracavity polarizer

A fiber laser with a comb-like spectrum

Polarization related phenomena in Nd-doped fiber lasers

Wavelength control in fiber lasers

Tunable fiber lasers with birefringent fiber Bragg grating mirrors