Perrine Toupin

Low loss microstructured chalcogenide fibers for large non linear effects at 1995 nm

Microstructured optical fibers (MOFs) are traditionally prepared using the stack and draw technique. In order to avoid the interfaces problems observed in chalcogenide glasses, we have developed a new casting method to prepare the chalcogenide preform. This method allows to reach optical losses around 0.4 dB/m at 1.55 µm and less than 0.05 dB/m in the mid IR. Various As(38)Se(62) chalcogenide microstructured fibers have been prepared in order to combine large non linear index of these glasses with the mode control offered by MOF structures. Small core fibers have been drawn to enhance the non linearities. In one of these, three Stokes order have been generated by Raman scattering in a suspended core MOF pumped at 1995 nm.

Small core Ge-As-Se microstructured optical fiber with single-mode propagation and low optical losses

Effects of multiple drawing operations on As38Se62 and Ge10As22Se68 chalcogenide microstructured optical fibers (MOF) are investigated. Fabrication of small-core single-mode chalcogenide MOF’s with 3 rings of holes necessitates a two-step drawing operation which may conduct to additional optical losses, as compared to single-step processes. Thus, glasses with high stability against crystallization are required. With this respect, Ge10As22Se68 single-mode microstructured optical were obtained with optical losses equal to 1 dB/m at 1.55 µm and lower than 1 dB/m at 3.0µm. Core diameter is as small as 4-6 µm.

Fourth-order cascaded Raman shift in AsSe chalcogenide suspended-core fiber pumped at 2 μm

Cascaded Raman wavelength shifting up to the fourth order ranging from 2092 to 2450 nm is demonstrated using a nanosecond pump at 1995 nm in a low-loss As(38)Se(62) suspended-core microstructured fiber. These four Stokes shifts are obtained with a low peak power of 11 W, and only 3 W are required to obtain three shifts. The Raman gain coefficient for the fiber is estimated to (1.6±0.5)×10(-11) m/W at 1995 nm. The positions and the amplitudes of the Raman peaks are well reproduced by the numerical simulations of the nonlinear propagation.

Efficient four-wave mixing in an ultra-highly nonlinear suspended-core chalcogenide As38Se62 fiber

We report a chalcogenide suspended-core fiber with ultra-high nonlinearity and low attenuation loss. The glass composition is As(38)Se(62).With a core diameter as small as 1.13 µm, a record Kerr nonlinearity of 46,000 W(-1) km(-1) is demonstrated with attenuation loss of 0.9 dB/m. Four-wave mixing is experimented by using a 1m-long chalcogenide fiber for 10 GHz and 42.7 GHz signals. Four-wave mixing efficiencies of -5.6 dB at 10 GHz and -17.5 dB at 42.7 GHz are obtained. We also observed higher orders of four-wave mixing for both repetition rates.

All-solid all-chalcogenide microstructured optical fiber.

The realization of an all-solid microstructured optical fiber based on chalcogenide glasses was achieved. The fiber presents As(2)S(3) inclusions selected as low refractive index material (n = 2.4) embedded in a As(38)Se(62) glass matrix (n = 2.8). The single mode regime of the fiber was demonstrated both theoretically by multipole method calculations and experimentally by near field measurements. Optical transmission measurements of the microstructured fiber and single index fibers made of the initial glasses reveal an excess of losses as high as 6-7 dB/m. This excess is not due to the guide geometry but can be explained by the presence of defects in the glass interface regions.

Relative intensity noise and frequency noise of a compact Brillouin laser made of As38Se62 suspended-core chalcogenide fiber.

Relative intensity noise and frequency noise have been measured for the first time for a single-frequency Brillouin chalcogenide As38Se62 fiber laser. This is also the first demonstration of a compact suspended-core fiber Brillouin laser, which exhibits a low threshold power of 22 mW and a slope efficiency of 26% for nonresonant pumping.

Optical Aging of Chalcogenide Microstructured Optical Fibers

The evolution with time of optical transmission of chalcogenide microstructured optical fibers has been studied. Microstructured optical fibers with “grapefruit” geometry (six holes) have been prepared from four glass compositions (Te₂₀As₃₀Se₅₀, As₃₈Se₆₂, Ge₁₀As₂₂ Se₆₈, and As₄₀S₆₀). Optical aging has been investigated by means of attenuation measurements carried out for each fiber. Fibers were stored in air between measurements. Transmission spectra show absorption bands due to O-H bonds and molecular water. Aging kinetics vary with glass compositions. For As₄₀S₆₀ glass, the O-H absorption band appears 2 h after the drawing step, while for Te₂₀As₃₀Se₅₀ glass that band is observed after an aging period as long as 21 months.

Linewidth-narrowing and intensity noise reduction of the 2nd order Stokes component of a low threshold Brillouin laser made of Ge10As24Se68 chalcogenide fiber

A compact second-order Stokes Brillouin fiber laser made of microstructured chalcogenide fiber is reported for the first time. This laser required very low pump power for Stokes conversion: 6 mW for first order lasing and only 30 mW for second order lasing with nonresonant pumping. We also show linewidth-narrowing as well as intensity noise reduction for both the 1st and 2nd order Stokes component when compared to that of the pump source.

Toward More Coherent Sources Using a Microstructured Chalcogenide Brillouin Fiber Laser

Up to 16-dB frequency noise reduction and a linewidth 8 times narrower than that of the pump source is reported for the Stokes component in a compact Brillouin fiber laser (BFL) made up of chalcogenide microstructured fiber. Since the pump wave is not resonant in the ring cavity, an active stabilization of the laser is not primordial, thus making the system simpler and cheaper. Although only a 3-meter-long microstructured chalcogenide fiber is used as gain medium, a very low laser threshold power of 6 mW is obtained for nonresonant pumping. The linewidth-narrowing effect achieved in our BFL cavity is also discussed.

Mid-infrared strong spectral broadening in microstructured tapered chalcogenide AsSe fiber

We report on the generation of a supercontinuum in a chalcogenide microstructured tapered fiber. The suspended core diameter of the fiber is reduced from 5.5 μm to 0.8 μm in the waist of the tapered region. The zero dispersion wavelength is below 2 μm in the tapered region. To pump the fiber, we use a modelocked laser of 4 ps, with a central wavelength of 1960 nm. With only 150 W peak power in the fiber a supercontinuum is generated from 1300 to 2600 nm taking the supercontinuum wavelength edge at -30 dB from the continuum.