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ABSTRACT: Fiber Bragg gratings are written across all 120 single-mode cores of a multi-core optical Fiber. The Fiber is interfaced to multimode ports by tapering it within a depressed-index glass jacket. The result is a compact multimode "photonic lantern" filter with astrophotonic applications. The tapered structure is also an effective mode scrambler.
Optics Express 06/2012; 20(13):13996-4008. · 3.59 Impact Factor
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ABSTRACT: Using ultrafast laser inscription, we report the fabrication of a prototype three-dimensional 121-waveguide fan-out device capable of reformatting the output of a 120-core multicore fiber (MCF) into a one-dimensional linear array. When used in conjunction with an actual MCF, we demonstrate that the reformatting function using this prototype would result in an overall through put loss of ≈7.0 dB. However, if perfect coupling from the MCF into the fan-out could be achieved, the reformatting function would result in an overall loss of only ≈1.7 dB. With adequate development, similar devices could efficiently reformat the output of so-called "photonic lanterns" fabricated using highly multicore fibers.
Optics Letters 06/2012; 37(12):2331-3. · 3.40 Impact Factor
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ABSTRACT: We report optofluidic waveguides made by filling microchannels in aerogel with water. The aerogel cladding is a nanoporous material with an extremely low refractive index of ~1.05, giving a large index step from the water core. Channels were formed by removing embedded optical fibers, which could be nonuniform or multiple. The porosity of the aerogel allowed air to be displaced from the channel, preventing the trapping of bubbles. The attenuation of red light in the highly multimode water core waveguide was no greater than 1.5 dB/cm.
Optics Letters 08/2011; 36(16):3275-7. · 3.40 Impact Factor
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ABSTRACT: Astrophotonics is the application of photonic principles to astronomical instrumentation, in order to reduce cost, size, weight and complexity while increasing performance. In astrophotonics the "photonic lantern" (PL) is a remarkable photonic device which efficiently couples light between a multimode (MM) optical fibre and a set of degenerate single modes (SMs) which are guided by the cores of either individual SM fibres or a multicore optical fibre. If the SMs produced by the PL are arranged into a linear array, the PL facilitates the efficient collection of light from a telescope using a MM fibre and the low-loss reformatting of this light into a near diffraction limited input (in one axis) for a spectrometer.
Lasers and Electro-Optics Europe (CLEO EUROPE/EQEC), 2011 Conference on and 12th European Quantum Electronics Conference; 06/2011
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ABSTRACT: We fabricated optical microfiber knot resonators from thin tapered fibers (diameter down to 1 μm) linked to untapered fiber at both ends. We demonstrated a finesse of about 100, over twice as high as previously reported for microfiber resonators. Low-loss encapsulation of microfiber knot resonators in hydrophobic silica aerogel was also investigated.
Optics Letters 04/2011; 36(7):1098-100. · 3.40 Impact Factor
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ABSTRACT: We used ultrafast laser inscription to fabricate three-dimensional integrated optical transitions that efficiently couple light from a multimode waveguide to a two-dimensional array of single mode waveguides and back. Although the entire device has an average insertion loss of 5.7 dB at 1539 nm, only ≈0.7 dB is due to mode coupling losses. Based on an analysis which is presented in the paper, we expect that our device should convert a multimode input into an array of single modes with a loss of ≈2.0 dB, assuming the input coupling losses are zero. Such devices have applications in astrophotonics and remote sensing.
Optics Express 03/2011; 19(6):5698-705. · 3.59 Impact Factor
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ABSTRACT: We replace the air around tapered silica fibres or within hollow-core photonic crystal fibres with silica aerogel. This retains the important device characteristics, including gas permeability, but adds protection and enables new devices.
Winter Topicals (WTM), 2011 IEEE; 02/2011
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ABSTRACT: Nanofibres, optical fibres narrower than the wavelength of light, degrade in hours on exposure to air. We show that encapsulation in hydrophobic silica aerogel (refractive index 1.05) provides protection and stability (over 2 months) without sacrificing low attenuation, strong confinement and accessible evanescent field. The measured attenuation was <0.03 dB/mm, over 10 × lower than reported with other encapsulants. This enables many nanofibre applications based on their extreme small size and strong external evanescent field, such as optical sensors, nonlinear optics, nanofibre circuits and high-Q resonators. The aerogel is more than a waterproof box, it is a completely-compatible gas-permeable material in intimate contact with the nanofibre and hydrophobic on both the macroscopic and molecular scales. Its benefits are illustrated by experiments on gas sensing (exploiting the aerogel's porosity) and supercontinuum generation (exploiting its ultra-low index).
Optics Express 01/2011; 19(2):764-9. · 3.59 Impact Factor
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ABSTRACT: We describe an idealised "kagome-like" hollow-core fibre that supports a mode that is strictly localised (that is, exponentially confined, without leakage loss) despite the co-existence of cladding modes with the same effective index and symmetry.
Optical Communication (ECOC), 2010 36th European Conference and Exhibition on; 10/2010
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ABSTRACT: We have selectively filled the core of hollow photonic crystal fibre with silica aerogel. Light is guided in the aerogel core, with a measured attenuation of 0.2 dB/cm at 1540 nm comparable to that of bulk aerogel. The structure guides light by different mechanisms depending on the wavelength. At long wavelengths the effective index of the microstructured cladding is below the aerogel index of 1.045 and guidance is by total internal reflection. At short wavelengths, where the effective cladding index exceeds 1.045, a photonic bandgap can guide the light instead. There is a small region of crossover, where both index- and bandgap-guided modes were simultaneously observed.
Optics Express 10/2010; 18(21):22497-502. · 3.59 Impact Factor
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ABSTRACT: Silica aerogel is a very light and highly porous form of silica glass, with densities and refractive indices much lower than those of ordinary solids. We describe optical interactions with aerogel surrounding tapered fibres or inside the holes of photonic crystal fibres. This enables a new class of fibre devices exploiting the properties of the aerogel as a rigid yet porous replacement for air, as a nonlinear medium and as a host for dopants. Examples include a stable package for fused couplers, a gas sensor and a nonlinear light source.
Transparent Optical Networks (ICTON), 2010 12th International Conference on; 08/2010
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ABSTRACT: We have formed low-loss fusion splices from highly nonlinear (HNL) photonic crystal fibers (PCFs) with small cores and high air-filling fractions to fibers with much larger mode field diameters (MFDs). The PCF core was locally enlarged by the controlled collapse of holes around the core while keeping other holes open. The fiber was then cleaved at the enlarged core and spliced to the large MFD fiber with a conventional electric arc fusion splicer. Splice losses as low as 0.36 dB were achieved between a PCF and a standard single-mode fiber (SMF) with MFDs of 1.8 microm and 5.9 microm, respectively.
Optics Letters 07/2009; 34(14):2240-2. · 3.40 Impact Factor
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ABSTRACT: We demonstrate low bend loss for tightly bent optical fibers by winding the fiber around a mandrel designed to follow an adiabatic transition path into the bend. Light in the fundamental core-guided mode is smoothly transferred to a single cladding mode of the bent fiber, and back to the core mode as it leaves the bent region again. Design of the transition is based on modeling of the propagation and coupling characteristics of the core and cladding modes, which clearly illustrate the physical processes involved.
Optics Express 03/2009; 17(4):2962-7. · 3.59 Impact Factor
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ABSTRACT: We report on the design, fabrication and characterization of silica square-lattice hollow core photonic crystal fibers optimized for low loss guidance over an extended frequency range in the mid-IR region of the optical spectrum. The fiber's linear optical properties include an ultra-low group velocity dispersion and a polarization cross-coupling as low as -13.4 dB over 10 m of fiber.
Optics Express 01/2009; 16(25):20626-36. · 3.59 Impact Factor
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ABSTRACT: We describe two all-fiber devices for converting light from the fundamental mode to the second-order set of modes in optical fibers. The first is made by controlled hole collapse in a photonic crystal fiber, and the second is a twisted fused coupler made from few-moded conventional fiber. As well as having applications within fiber optics, the devices can be used to generate azimuthally polarized free-space beams.
Optics Letters 03/2008; 33(4):306-8. · 3.40 Impact Factor
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ABSTRACT: New methods have been developed in post-processing and tapering of PCFs to achieve a variety of low-loss optical devices. Interfacing between waveguides with very different properties and highly efficient mode convertors are presented.
IEEE/LEOS Winter Topical Meeting Series, 2008; 02/2008
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ABSTRACT: We report on the fabrication and characterization of hollow-core photonic bandgap fibers that do not suffer from surface mode coupling within the photonic bandgap of the cladding. This enables low attenuation over the full spectral width of the bandgap--we measured a minimum loss of 15 dB/km and less than 50 dB/km over 300 nm for a fiber operating at 1550 nm. As a result of the increased bandwidth, the fiber has reduced dispersion and dispersion slope--by a factor of almost 2 compared to previous fibers. These features are important for several applications in high-power ultrashort pulse compression and delivery. Realizing these advances has been possible due to development of a modified fabrication process which makes the production of low-loss hollow-core fibers both simpler and quicker than previously.
Optics Express 02/2008; 16(2):1142-9. · 3.59 Impact Factor
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ABSTRACT: Photonic crystals are formed of a regularly patterned microstructured material, with a pitch comparable to the optical wavelength.
These materials exhibit unusual optical properties due to the interference of the light scattered at the different interfaces,
and this has remarkable consequences such as the formation of photonic band gaps. One way of making 2-dimensional photonic
crystal materials is to use the technology of optical fibre fabrication. We describe how new optical properties arise in such
media, and how they can be used to form novel optical waveguide structures.
01/2008: pages 253-267;
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Denis A Akimov,
Anatoliy A Ivanov,
Mikhail V Alfimov,
Andrei B Fedotov, T A Birks,
W J Wadsworth,
P St J Russell,
O A Kolevatova,
Stanislav O Konorov,
Alexey A Podshivalov,
Aleksandr N Petrov,
D A Sidorov-Biryukov,
Aleksei M Zheltikov
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ABSTRACT: Efficient frequency conversion of femtosecond pulses of a Cr:forsterite laser in tapered fibres is experimentally demonstrated. Unamplified 30-fs Cr:forsterite-laser pulses are used to generate the third harmonic in the phase-matching regime. Propagation of 75-fs, 10–200-nJ Cr:forsterite-laser pulses through a tapered fibre in the range of anomalous dispersion is accompanied by multiply phase-matched cascaded four-wave mixing, giving rise to a manifold of new spectral components in the visible range and substantial spectral broadening within the wavelength range from 1300 to 1600 nm.
Quantum Electronics 10/2007; 33(4):317. · 0.83 Impact Factor
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ABSTRACT: Photonic crystal fibers (PCFs) exploit the large index difference between air and glass to achieve modal properties unattainable
by conventional fiber techniques.
09/2007: pages 313-339;
