1,720,978 research outputs found
Optical quality ZnSe films and low loss waveguides on Si substrates for mid-infrared applications
No full textData for the paper Mittal, Vinita, Sessions, Neil, Wilkinson, James and Ganapathy, Senthil (2017) Optical quality ZnSe films and low loss waveguides on Si substrates for mid-infrared applications. Optical Materials Expres, 7, (3), 712-725. (doi:10.1364/OME.7.000712).</span
Optical quality ZnSe films and low loss waveguides on Si substrates for mid-infrared applications
Full text linkZinc Selenide (ZnSe) is a promising mid-infrared waveguide material with high refractive index and wide transparency. Optical quality ZnSe thin films were deposited on silicon substrates by RF sputtering and thermal evaporation, and characterized and compared for material and optical properties. Evaporated films were found to be denser and smoother than sputtered films. Rib waveguides were fabricated from these films and evaporated films exhibited losses as low as 0.6 dB/cm at wavelengths between 2.5 µm and 3.7 µm. The films were also used as isolation/lower cladding layers on Si with GeTe4 as the waveguide core and propagation losses were determined in this wavelength range
Modelling of a miniature mid-IR thermo-optic spectrometer on chip based on a GaAs/In<sub>0.49</sub>Ga<sub>0.51</sub>P waveguide platform
No full textSpectrometers based on integrated optical waveguides, as opposed to free space optics, provide many advantages including robustness, compactness, and low cost, combined with alignment-free and low-power operation. Interest in such a chip-based approach for integrated spectrometers is growing, but the integrated spectrometers demonstrated so far have largely been limited to operation at wavelengths up to about 5μm due to intrinsic material absorption. In this work, we design and model an on-chip thermo-optically tuneable spectrometer based on a novel waveguide material platform consisting of GaAs (core) on InGaP (cladding), with potential to operate in the wavelength range between 1 and 17μm to fully cover the Mid-IR molecular fingerprint region. The strong thermo-optic effect exhibited by both of these materials makes the platform a very promising candidate for on-chip spectroscopy. A series of simulations were performed to predict the optical and thermal properties of the device. We show that with the proper optical and thermal optimisation of the platform and by using an interferometer with spiralled waveguides of 60 mm length, the device can effectively achieve a resolution of 10 cm
−1 with a maximum temperature excursion of about 83 K and at the cost of a few tens of Watts of power.
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Etchless pedestal chalcogenide waveguide platform for long-wave IR applications
No full textWe report the fabrication of GeAsSeTe/GeAsSe waveguides using a simple and cost-effective process. Chalcogenides are very delicate materials and can be degraded when in contact with developer solutions during photolithography and when processed using common etchants, making the use of conventional fabrication processes unattractive. In order to avoid any post-film deposition processing for the fabrication of chalcogenide waveguides, we pre-patterned pedestal structures on silicon substrates using photolithography and a simple wet-etch process followed by the deposition of chalcogenide films on the patterned structures. Using the scattered light decay fitting method, we estimated waveguide propagation losses averaging approximately 0.9 dB/cm for wavelengths between 7 and 11 μm. With these findings we show that this waveguide platform is a very attractive candidate for long-wave infrared applications
Efficient light confinement to λ/10 spot sizes in optical fibre
No full textLight confinement beyond the diffraction limit has been achieved in optical fibre tips. We successfully fabricated a gold-coated optical fibre tip with wedge-shaped apex for the efficient excitation of surface plasmon polaritons (SPPs). An improved transmissivity higher than 10-2 and spot sizes of the order of λ/10 have been obtained by optimizing the overall light throughput along the fibre tip
Dataset for "Modelling of a miniature mid-IR thermo-optic spectrometer on chip based on a GaAs/In0.49Ga0.51P waveguide platform"
No full textThis dataset supports the publication: Mourgelas Vasileios et al (2021) ."Modelling of a miniature mid-IR thermo-optic spectrometer on chip based on a GaAs/In0.49Ga0.51P waveguide platform". Optics Communications</span
Εtchless Pedestal Chalcogenide Waveguide Platform for Long-Wave IR Sensing Applications
No full textThis dataset supports the publication: Mourgelas Vasileios et al (2022) ."Εtchless Chalcogenide Waveguide Platform for Long-Wave IR Sensing Applications". </span
Tm<sup>3+</sup> doped tellurite glass for S band amplifiers
No full textIn the past, much effort has been devoted solely to the development of fiber amplifiers operating in the C(1530-1560nm) and L(1560-1610nm) bands based on Er-doped fiber amplifiers. However, with the rapid increase in data transmission, the demand for a larger bandwidth to handle a larger transmission capacity has become vital. We report on the spectroscopy and gain measurements in a thulium (Tm3+) doped tellurite glass for broadband amplification in the S band (1440-1530nm). The composition presented here is LTT: 25Li2O+5TiO2+70TeO2. Based on DTA measurement, the glass transition temperature of Tg is ~270°C and there is no apparent crystallization. The 1470nm fluorescence profile is independent of concentration and the full width at half maximum is ~106nm which is at least 30nm broader than that reported in fluoride ZBLAN glass. The 1470nm transition is ~97 % radiative, the effect of OH quenching is minor and the glass can accept large dopant levels. The 3H4-3F4 transition is self-terminating unless the lower 3F4 level is depopulated. Our results on a 2000ppm Tm3+-Ho3+ codoped LTT glass shows a 33% reduction in the lifetime of the 3F4 state without affecting the lifetime of the 3H4. It is estimated that a Ho3+ concentration of 10,000ppm is required. A multimode LTT fiber doped with 2000ppm of Tm3+ with a NA of ~0.45 and a core diameter of 40µm has been fabricated. The background loss is 3dB/m at 1µm. Gain measurements were performed in free space configuration using 800nm from a Ti:Sapphire laser as a pump source and a HP tunable laser diode between 1470nm and 1580nm as the signal source. The pump power incident on the fiber was ~1W uncorrected for coupling losses whilst the signal power was maintained at -55dBm. A 0.30m length fiber shows gain extending to a longer wavelength (1560nm) than that reported in ZBLAN. An average gain of 4dB was measured at 1470nm and the gain increases with pump power with a pump efficiency of ~3.5dB/W. The gain figure and pump efficiency will improve significantly in a single mode fiber
Waveguide lasers in ytterbium-doped tantalum pentoxide on silicon
No full textA waveguide laser in an ytterbium doped tantalum pentoxide film is reported. The waveguide is formed of a rib of sputtered tantalum pentoxide on top of oxidized silicon with an over-cladding of silica. Emission at a wavelength of 1025 nm was achieved with an absorbed pump power threshold and slope efficiency of ~ 29 mW and 27% respectively for a cavity formed by a high reflector mirror and an estimated 12% Fresnel reflection from the bare end-face at the output.</span
Spectroscopy of high index contrast Yb:Ta<sub>2</sub>O<sub>5</sub> waveguides for lasing applications
No full textYtterbium-doped waveguides are required for compact integrated lasers and Yb-doped Ta2O5 is a promising candidate material. The design, fabrication and spectroscopic characterisation of Yb:Ta2O5 rib waveguides are described. The peak absorption cross-section was measured to be 2.75 x 10-20 cm2 at 975 nm. The emission spectrum was found to have a fluorescence emission peak at a wavelength of 976 nm with a peak cross-section of 2.9 x 10-20 cm2 and a second broad fluorescence band spanning from 990 nm to 1090 nm. The excited-state life time was measured to be 260 µs
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