Effect of graphite oxide electrochemically exfoliated over a multimode interference filter.

In this work, we study multimodal interference filters with a graphite oxide coating. Use of the multimodal interference filter shows a distinctive peak in the signal spectrum, and when using the exfoliated graphite coated multimodal interference filter, the signal shows different spectral changes, such as the full width at half maximum of the curve, the maximum power, and central wavelength, which indicates that graphite oxide absorbs part of the energy. In addition, microscope observations when a He-Ne laser is passed through the filter confirm that graphite oxide is adhered to the filter.

Theoretical and experimental analysis of tunable Sagnac high-birefringence loop filter for dual-wavelength laser application.

We present detailed investigations of the spectral dependencies of the transmission of a fiber optical loop mirror (FOLM) consisting of a coupler with output ports spliced at arbitrary angles to a high-birefringence (Hi-Bi) fiber. The application for dual-wavelength lasers is discussed. For this aim, the spectral dependence of the reflection is tuned by the temperature of the Hi-Bi fiber that allows a fine adjustment of the cavity loss for generated wavelengths. The ratio between maximum and minimum reflection can be adjusted by the twist angle of the fiber at the splices, which also provides useful possibilities for the adjustment of cavity losses. We used the twist and temperature variation of the Hi-Bi fiber to change the operation from single wavelength to stable dual-wavelength generation with either equal or unequal powers of wavelengths.

Experimental investigation of the extraction of solitons at the initial stage of the soliton formation process.

We demonstrate the extraction of a single soliton from a bunch of solitons generated by the pulse breakup effect. The bunch of solitons was generated in a 500-m fiber pumped by 25-ps pulses. For the extraction of single soliton from the bunch we use a nonlinear optical loop mirror (NOLM). At its output we detected a pulse with full width at half-maximum (FWHM) of 0.99 ps whose autocorrelation trace corresponds to that of a soliton. Our results demonstrate that the suggested method can be useful for soliton generation, and also for investigations of the initial stage of the soliton formation process.

Initial development of supercontinuum in fibers with anomalous dispersion pumped by nanosecond-long pulses.

We propose and compare with experimental data a two-stage model of supercontinuum formation in a fiber for nanosecond-long pulse with intensities in 10 W range. As a result of the first stage, the sea of solitons is formed. The second stage is spectrum modification because of Raman interaction.