1,721,038 research outputs found
Fabrication of arbitrarily narrow vertical dielectric slots in silicon waveguides
No full textSlot waveguides are used for many photonic applications. However, existing fabrication techniques impose restrictions on the width of the slot region. Here we propose and experimentally demonstrate a fabrication process to realize an arbitrarily narrow vertical dielectric slot in a silicon waveguide. Using this fabrication method we have realized silicon slot waveguides with a 10 nm oxide slot region. The propagation loss of the fabricated slot waveguide was 1.36±0.3 dB/mm
Hot-wire chemical vapour deposition for silicon nitride waveguides
No full textIn this work, we demonstrate the use of HWCVD as an alternative technique to grow SiN layers for photonic waveguides at temperatures <400ºC. In particular, the effect of the ammonia flow and the filament temperature on the material structure, optical properties and propagation losses of the deposited films was investigated. SiN layers with good thickness uniformity, roughness as low as 0.61nm and H concentration as low as 10.4×1021 atoms/cm3 were obtained. Waveguides fabricated on the studied materials exhibited losses as low as 7.1 and 12.3 dB/cm at 1310 and 1550nm respectively
Mid-infrared silicon-on-insulator Fourier-transform spectrometer chip
No full textMid-infrared absorption spectroscopy is highly relevant for a wide range of sensing applications. In this letter, we demonstrate a Fourier-transform spectrometer chip based on the principle of spatial heterodyning implemented in the silicon-on-insulator waveguide platform, and operating near 3.75-\u3bcm wavelength. The spectrometer comprises a waveguide splitting tree feeding to an array of 42 Mach-Zehnder interferometers with linearly increasing optical path length differences. A spectral retrieval algorithm based on calibration matrices is applied to the stationary output pattern of the array, compensating for any phase and amplitude errors arising from fabrication imperfections. A spectral resolution below 3 nm is experimentally demonstrated.Peer reviewed: YesNRC publication: Ye
Dual-etch apodised grating couplers for efficient fibre-chip coupling near 1310 nm wavelength
No full textWe present our recent work on fibre-chip grating couplers operating around 1310 nm. For the first time, we demonstrate the combination of dual-etch and apodization design approaches which may achieve a coupling efficiency of 85% (-0.7 dB). Subwavelength structures were employed to modify the coupling strength of the grating. -1.9 dB efficiency was measured from a first set of fabricated structures
N-rich silicon nitride angled-MMI for coarse wavelength division (de)multiplexing in the O-band
No full textWe report the design and fabrication of a compact angled multimode interferometer (AMMI) on a 600nm thick N-rich silicon nitride platform (n=1.92) optimised to match the International Telecommunication Union (ITU) coarse wavelength division (de)multiplexing (CWDM) standard in the O telecommunication band. The demonstrated device exhibited a good spectral response with ∆λ=20nm, BW3dB ∼11nm, IL<1.5dB and XT∼20dB. Additionally, it showed a high tolerance to dimensional errors <120pm/nm and low sensitivity to temperature variations <20pm/ºC, respectively. This device had a footprint of 0.02×1.7mm2 with the advantage of a simple design and a back-end-of-line compatible fabrication process that enables multilayer integration schemes due to its processing temperature <400ºC
Optical waveguides by germanium ion implantation on silicon-on-insulator platform
No full textWe demonstrated a new type of integrated photonic waveguides formed by Ge ion implantation in the silicon slab on silicon-on-insulator platform. They were successfully fabricated and characterised, and can be potentially erased by laser annealing.</p
Negative index fishnet with nanopillars formed by direct nano-imprint lithography
Full text linkIn this paper we demonstrate the ability to fabricate fishnets by nanoimprinting directly into a pre-deposited three layer metal–dielectric–metal stack, enabling us to pattern large areas in two minutes. We have designed and fabricated two different fishnet structures of varying dimensions using this method and measured their resonant wavelengths in the near-infrared at 1.45 μm and 1.88 μm. An important by-product of directly imprinting into the metal–dielectric stack, without separation from the substrate, is the formation of rectangular nanopillars that sit within the rectangular apertures between the fishnet slabs. Simulations complement our measurements and suggest a negative refractive index real part with a magnitude of 1.6. Further simulations suggest that if the fishnet were to be detached from the supporting substrate a refractive index real part of 5 and FOM of 2.74 could be obtained
Towards autonomous testing of photonic integrated circuits
No full textA crucial component of any large scale manufacturing line is the development of autonomous testing at the wafer scale. This work offers a solution through the fabrication of grating couplers in the silicon-on-insulator platform via ion implantation. The grating is subsequently erased after testing using laser annealing without affecting the optical performance of the photonic circuit. Experimental results show the possibility for the realisation of low loss, compact solutions which may revolutionise photonic wafer-scale testing. The process is CMOS compatible and can be implemented in other platforms to realise more complex systems such as multilayer photonics or programmable optical circuits
Two-dimensional apodized grating coupler for polarization-independent and surface-normal optical coupling
No full textA four-port grating coupler with etched square holes is proposed and demonstrated for surface-normal and polarization independent coupling. Benefiting from the perfectly vertical coupling and 1 × 4 power splitting/combing scheme, efficient polarization independent operation was achieved. The coupling efficiency was further improved by grating apodization. According to the simulations, the proposed 2D apodized grating coupler can achieve a coupling efficiency (CE) of 64.5% (-1.9 dB), a low upward back-reflection of 8.5% (-11 dB), and polarization-dependent loss (PDL) lower than 0.04 dB across the wavelength range of 1520-1620 nm. A CE of 56.3% (-2.5 dB) was experimentally measured, with PDL below 0.3 dB within the C-band and lower than 0.5 dB within the L-band. Waveguide delay lines were used to compensate the waveguide channel phase differences at the output port.</p
Surface-grating-coupled low-loss Ge-on-Si rib waveguides and multimode interferometers
No full textGermanium-on-silicon is a highly promising platform for planar photonics for the midinfrared, due to germanium’s wide transparency range. In this letter, we report Ge-on-Si waveguides with record low losses of only 0.6 dB/cm, which is achieved using a 2.9 µm thick germanium layer, thus minimizing mode interaction with dislocations at the germanium/silicon interface. Using these waveguides, multimode interferometers with insertion losses of only 0.21 ± 0.02 dB are also demonstrated
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