Eric Magi

Low-threshold supercontinuum generation in highly nonlinear chalcogenide nanowires

We demonstrate low-threshold supercontinuum generated in a highly nonlinear arsenic selenide chalcogenide nanowire with tailored dispersion. The tapered submicrometer chalcogenide fiber exhibits an ultrahigh nonlinearity, n(2) approximately 1.1x10(-17) m(2)/W and an effective mode area of 0.48 mum(2), yielding an effective nonlinearity of gamma approximately 93.4 W/m, which is over 80,000 times larger than standard silica single-mode fiber at a wavelength of approximately 1550 nm. This high nonlinearity, in conjunction with the engineered anomalous dispersion, enables low-threshold soliton fission leading to large spectral broadening at a dramatically reduced peak power of several watts, corresponding to picojoule energy.

Enhanced Kerr nonlinearity in sub-wavelength diameter As2Se3 chalcogenide fiber tapers

We experimentally demonstrate enhanced Kerr nonlinear effects in tapered highly nonlinear As2Se3 chalcogenide fibre with 1.2 mum waist diameter. We observe nonlinearity enhanced by 40,000 times compared to standard silica single-mode fibre.

Tapered photonic crystal fibers

We demonstrate the tapering of a photonic crystal fiber to achieve a microstructure pitch of less than 300 nm. We probe the tapered fiber in the transverse geometry to demonstrate the scaling of the photonic bandgaps associated with the microstructure. We show that the fundamental gap can be shifted down to the communications wavelengths, or even further to the visible spectrum. Our optical measurements are correlated with band structure calculations.

Microstructured optical fiber photonic wires with subwavelength core diameter

We demonstrate fabrication of robust, low-loss silica photonic wires using tapered microstructured silica optical fiber. The fiber is tapered by a factor of fifty while retaining the internal structure and leaving the air holes completely open. The air holes isolate the core mode from the surrounding environment, making it insensitive to surface contamination and contact leakage, suggesting applications as nanowires for photonic circuits . We describe a transition between two different operation regimes of our photonic wire from the embedded regime, where the mode is isolated from the environment, to the evanescent regime, where more than 70% of the mode intensity can propagate outside of the fiber. Interesting dispersion and nonlinear properties are identified.

Low propagation loss silicon-on-sapphire waveguides for the mid-infrared

We report record low loss silicon-on-sapphire nanowires for applications to mid infrared optics. We achieve propagation losses as low as 0.8 dB/cm at λ = 1550 nm, ~1.1 to 1.4 dB/cm at λ = 2080 nm and < 2dB/cm at λ = 5.18 μm.We report record low loss silicon-on-sapphire nanowires for applications to mid infrared optics. We achieve propagation losses as low as 0.8dB/cm at =1550nm,  1.1 to 1.4dB/cm at =2080nm and < 2dB/cm at  = 5.18 μm.

Applications of Highly-Nonlinear Chalcogenide Glass Devices Tailored for High-Speed All-Optical Signal Processing

Ultrahigh nonlinear tapered fiber and planar rib Chalcogenide waveguides have been developed to enable highspeed all-optical signal processing in compact, low-loss optical devices through the use of four-wave mixing (FWM) and cross-phase modulation (XPM) via the ultra fast Kerr effect. Tapering a commercial As2Se3 fiber is shown to reduce its effective core area and enhance the Kerr nonlinearity thereby enabling XPM wavelength conversion of a 40 Gb/s signal in a shorter 16-cm length device that allows a broader wavelength tuning range due to its smaller net chromatic dispersion. Progress toward photonic chip-scale devices is shown by fabricating As2S3 planar rib waveguides exhibiting nonlinearity up to 2080 W-1ldr km-1 and losses as low as 0.05 dB/cm. The materials high refractive index, ensuring more robust confinement of the optical mode, permits a more compact serpentine-shaped rib waveguide of 22.5 cm length on a 7-cm- size chip, which is successfully applied to broadband wavelength conversion of 40-80 Gb/s signals by XPM. A shorter 5-cm length planar waveguide proves most effective for all-optical time-division demultiplexing of a 160 Gb/s signal by FWM and analysis shows its length is near optimum for maximizing FWM in consideration of its dispersion and loss.

Octave spanning supercontinuum in an As 2 S 3 taper using ultra-low pump pulse energy

An octave spanning spectrum is generated in an As2S3 taper via 77 pJ pulses from an ultrafast fiber laser. Chirp compensation allows the octave to be generated directly from the un-amplified laser output.

Enhanced Kerr Nonlinearity in Sub-wavelength Diameter As 2 Se 3 Chalcogenide Fibre Tapers

We experimentally demonstrate enhanced Kerr nonlinear effects in tapered highly nonlinear As2Se3 chalcogenide fibre with 1.2 mum waist diameter. We observe nonlinearity enhanced by 40,000 times compared to standard silica single-mode fibre.

Efficient coupling to chalcogenide glass photonic crystal waveguides via silica optical fiber nanowires

We demonstrate highly efficient evanescent coupling between a highly nonlinear chalcogenide glass two dimensional photonic crystal waveguide and a silica fiber nanowire. We achieve 98% insertion efficiency to the fundamental photonic crystal waveguide mode with a 3dB coupling bandwidth of 12nm, in good agreement with theory. This scheme provides a promising platform to realize low power nanocavity based all-optical switching and logic functions.

Long period grating resonances in photonic bandgap fiber

We demonstrate the formation of stress-induced long period gratings (LPGs) in fluid-filled photonic bandgap fiber (PBGF). Based on our experimental results, simulations, and theoretical understanding of LPGs, we identify coupling to a guided LP(11)-like mode of the core and lossy LP1x-like modes of cladding microstructure for a single grating period. The periodic modal properties of PBGFs allow for coupling to the same mode at multiple wavelengths without a dispersion turning point. Simulations identify inherent differences in the modal structure of even and odd bands.