Circular core polarization-maintaining optical fibers withelliptical stress-induced cladding

The reproducible technology for producing high-birefringence fibers with stress-induced elliptical cladding and circular core is described. The authors have obtained fibers that have a birefringence of about (1-3) 10^-4, a mode coupling parameter of about (2-7) 10 ^-5 m^-1, and loss of less than 0.5 dB/km at 1.6 μm. The authors have found effects restricting the capability of test fibers to maintain the state of linear polarization     

Coupled-cavity passive mode-locked injection laser

Experimental results on the observation of the self-initiating passive mode-locking operation of an injection laser with a nonlinear external-coupled-cavity configuration are presented. Michelson and Fabry-Perot cavity arrangements with similar laser diodes as both the gain medium and nonlinear element have been investigated. This technique can be used for generating short pulses with ultrahigh repetition rates without utilizing both high-modulation bandwidth laser diodes and ultrafast electronics, which do not require special saturable absorbers.<>     

Single-Mode As–S Glass Fibers

Single-mode As–S glass fibers with a core diameter from 3 to 20 m and a clad diameter of 125 m are prepared by the double-crucible method. The cutoff wavelength of the fibers is 0.9–6 m. The lowest transmission losses in the fibers at 2.2–2.3 m are 100 dB/km, and their mean bending strength is 800–1000 MPa.     

Medium-power CW Raman fiber lasers

A review of recent results on medium-power CW Raman fiber lasers pumped by laser diodes is presented. Most attention is given to Raman lasers based on phosphosilicate fibers, the latter providing a number of advantages compared to commonly used germanosilicate fibers     

Effect of fluorine doping on the optical loss in MCVD fibers based on heavily doped germanosilicate glass

We have studied the size distribution of silica glass particles in the fabrication of heavily doped germanosilicate glass fiber preforms by modified chemical vapor deposition (MCVD) at different Freon 113 concentrations in the gas mixture. The addition of Freon 113 to the gas mixture is shown to reduce the particle size in the deposited core glass layer and the optical loss in the fiber. A mechanism is proposed which accounts for the effect of the initial particle size in the core glass layer on the anomalous scattering and total optical loss in heavily doped step- and graded-index fibers.     

Preparation of mid-IR-active As2S3/ZnS(ZnSe):Cr2+ composites

We have studied novel materials promising for fiber-optic applications: composites in the form of As₂S₃ glass containing Cr²⁺-doped zinc chalcogenide particles. Their dispersion characteristics and optical properties have been investigated in relation to preparation conditions. Process parameters have been found that enable the fabrication of optical fibers possessing luminescence properties.     

Amplification of femtosecond pulses in Er/sup 3+/-doped single-mode optical fibres

Femtosecond pulse amplification in Er/sup 3+/-doped single-mode optical fibres has been experimentally investigated. The effect of amplified pulse compression from 80 to 55 fs has been observed. The amplified pulse energy was evaluated as 5 nJ. Maximum gain for the amplified signal was 26 dB.<>     

Advances in Raman fibers

Raman fiber lasers and amplifiers will play an increasing role in future optical fiber communication (OFC) systems. Recent progress in the development of special Raman fibers is described. We particularly focus on high /spl Delta/n germanosilicate and phosphosilicate fibers.