Highly evanescent nanophotonic waveguides enable extremely efficient Raman spectroscopy in chip-scale photonic integrated circuits due to the continuous excitation and collection of Raman scattering along the entire w...
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ISBN:
(纸本)9781510600652
Highly evanescent nanophotonic waveguides enable extremely efficient Raman spectroscopy in chip-scale photonic integrated circuits due to the continuous excitation and collection of Raman scattering along the entire waveguide length. Such waveguides can be used for detection and identification of condensed-phase analytes, or, if functionalized by a sorbent as a top-cladding, can be used to detect trace concentrations of chemical species. The scattering efficiency is modified in guided-mode structures compared to unconfined, micro-Raman geometries. Here, we describe the theoretical framework for understanding the Raman scattering efficiency in nanophotonic waveguides, and compare these calculations to our measurements of trace gases in hypersorbent-clad silicon nitride waveguides.
Despite all the eminent advantages of silicon photonics, other materials need to be integrated to fulfill the functions that are difficult to realize with silicon alone. This is because silicon has a low light emissio...
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ISBN:
(纸本)9781510601369
Despite all the eminent advantages of silicon photonics, other materials need to be integrated to fulfill the functions that are difficult to realize with silicon alone. This is because silicon has a low light emission efficiency and a low electro-optic coefficient, limiting the use of silicon as a material for light sources and modulators. A strong two-photon absorption (TPA) at high intensities also limits the use of silicon in applications exploiting nonlinear effects. In addition, signal amplification is needed to compensate the insertion and propagation losses in silicon nanowaveguides. To address these issues we have demonstrated the integration of atomic layer deposited nanolaminates on silicon waveguides.
Firstly we demonstrate slot waveguide ring resonators patterned on a silicon-on-insulator (SOI) wafer coated with an atomic layer deposited organic/inorganic nanolaminate structure, which consists of alternating layers of tantalum pentoxide (Ta2O5) and polyimide (PI) [1]. These materials were selected since the ALD process for depositing Ta2O5/PI nanolaminate films is already available [2] and both materials exhibit high third order nonlinearities [3-4]. In our nanolaminate ring resonators, the optical power is not only confined in the narrow central air slot but also in several parallel sub-10 nm wide vertical polyimide slots. This indicates that the mode profiles in the silicon slot waveguide can be accurately tuned by the atomic layer deposition (ALD) method. Our results show that ALD of organic and inorganic materials can be combined with conventional silicon waveguide fabrication techniques to create slot waveguide ring resonators with varying mode profiles.
Secondly we demonstrate the integration of atomic layer deposited erbium-doped aluminum oxide (Al2O3) nanolaminates on silicon waveguides. This method provides an efficient way for controlling the concentration and distribution of erbium ions. We have applied this method on silicon strip and slot
The propagation properties of 1D waveguides composed by a dielectric core and a multilayered metallic dielectric cladding are numerically analyzed in details for applications covering the O-E-S-C-L-U optical communica...
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ISBN:
(数字)9781510602281
ISBN:
(纸本)9781510602274;9781510602281
The propagation properties of 1D waveguides composed by a dielectric core and a multilayered metallic dielectric cladding are numerically analyzed in details for applications covering the O-E-S-C-L-U optical communication bands. The propagation length, penetration depth and the figure of merit as a function of their geometrical and optical parameters are presented. The strong dependence of their properties with their constituent materials has been observed. Long propagation distances with high values of figure of merit can be obtained, opening the possibility to develop devices of high performance in the optical band under inspection.
Ridge waveguides in ferroelectric materials like LiNbO3 attended great interest for highly efficient integrated optical devices, for instance, electro-optic modulators, frequency converters and ring resonators. The ma...
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ISBN:
(纸本)9781628419948
Ridge waveguides in ferroelectric materials like LiNbO3 attended great interest for highly efficient integrated optical devices, for instance, electro-optic modulators, frequency converters and ring resonators. The main challenges are the realization of high index barrier towards the substrate and the processing of smooth ridges for minimized scattering losses. For fabricating ridges a variety of techniques, like chemical and wet etching as well as optical grade dicing, have been investigated in detail. Among them, laser micromachining offers a versatile and flexible processing technology, but up to now only a limited side wall roughness has been achieved by this technique. Here we report on laser micromachining of smooth ridges for low-loss optical waveguides in LiNbO3. The ridges with a top width of 7 mu m were fabricated in z-cut LiNbO3 by a combination of UV picosecond micromachining and thermal annealing. The laser processing parameters show a strong influence on the achievable sidewall roughness of the ridges and were systematically investigated and optimized. Finally, the surface quality is further improved by an optimized thermal post-processing. The roughness of the ridges were analysed with confocal microscopy and the scattering losses were measured at an optical characterization wavelength of 632.8 nm by using the end-fire coupling method. In these investigations the index barrier was formed by multi-energy low dose oxygen ion implantation technology in a depth of 2.7 mu m. With optimized laser processing parameters and thermal post-processing a scattering loss as low as 0.1 dB/cm has been demonstrated.
Power scaling analysis based on the model by Dawson et al. [1,2] for circular core fibers has been applied to estimating power scaling of crystalline fiber waveguides (CFWs) with RE3+ doped single crystalline or ceram...
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ISBN:
(纸本)9781628419795
Power scaling analysis based on the model by Dawson et al. [1,2] for circular core fibers has been applied to estimating power scaling of crystalline fiber waveguides (CFWs) with RE3+ doped single crystalline or ceramic YAG (RE=rare earth: Yb, Er, Tm and Ho). Power scaling limits include stimulated Brillouin scattering, thermal lensing effect, and limits to coupling of pump light into CFWs. The CFW designs we have considered consist, in general, of a square doped RE3+:YAG core, an inner cladding of either undoped or laser-inactive-ion-doped YAG and an outer cladding of sapphire. The presented data have been developed for the structures fabricated using the Adhesive-Free Bonding (AFB (R)) technique, but the results should be essentially independent of fabrication technique, assuming perfect core/inner cladding/outer cladding interfaces. Hard power scaling limits exist for a specific CFW design and are strongly based on the physical constants of the material and its spectroscopic specifics. For example, power scaling limit was determined as similar to 16 kW for 2.5% ceramic Yb:YAG/YAG (core material/inner cladding material) at fiber length of 1.7 m and core diameter of 69 mu m. Considering the present manufacturing limit for CFW length to be, e.g., 0.5 m, the actual maximum output power will be limited to similar to 4.4 kW for a Yb:YAG/YAG CFW. Power limit estimates have also been computed for Er3+, Tm3+ and Ho3+ doped core based CFWs.
We developed a general method for direct and fully integrated generation of photon pairs in counter-propagating spatially entangled Bell-states using parametric down-conversion in photonic crystal slab waveguides with...
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ISBN:
(纸本)9781943580118
We developed a general method for direct and fully integrated generation of photon pairs in counter-propagating spatially entangled Bell-states using parametric down-conversion in photonic crystal slab waveguides without the need for periodic poling.
We determine the radiation loss for modulated potentials analytically and implement this setting experimentally utilizing laser-written photonic waveguides. We foresee numerous applications, in particular in PT-symmet...
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ISBN:
(纸本)9781943580118
We determine the radiation loss for modulated potentials analytically and implement this setting experimentally utilizing laser-written photonic waveguides. We foresee numerous applications, in particular in PT-symmetric systems.
We propose a pressure sensor based on two optical waveguides to be coupled vertically. The sensor operates by the change in the coupling constant between the optical waveguides when a pressure is applied to them. We d...
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ISBN:
(纸本)9781943580118
We propose a pressure sensor based on two optical waveguides to be coupled vertically. The sensor operates by the change in the coupling constant between the optical waveguides when a pressure is applied to them. We designed and realized the sensor by using of polymer and PDMS.
This paper describes a computer vision based robotic waveguide flange alignment system that achieves improved repeatability of waveguide measurements. The proof-of-concept is demonstrated using WR-62 in the frequency ...
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ISBN:
(纸本)9782874870439
This paper describes a computer vision based robotic waveguide flange alignment system that achieves improved repeatability of waveguide measurements. The proof-of-concept is demonstrated using WR-62 in the frequency band 12.40 GHz to 18 GHz. An Arduino board was used to interface a three channel NTS NanoDirect XYZ positioner with MATLAB and its image acquisition toolbox. The measured results of a back-to-back adapter pair demonstrate significantly improved repeatability with the automated system compared with manual alignment. Through EM modelling of two WR-1.0 rectangular waveguides over the frequency range 800 GHz to 1 THz it is shown that this new method for enhancing measurement repeatability will be invaluable.
In this study, phononic crystals are employed to elastic waveguide transducers for controlling its beam patterns. When signals from the transducer array are inputted to a homogeneous waveguide, they are distorted as p...
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ISBN:
(纸本)9781467398978
In this study, phononic crystals are employed to elastic waveguide transducers for controlling its beam patterns. When signals from the transducer array are inputted to a homogeneous waveguide, they are distorted as propagating due to generation of multiple wave modes and wave dispersion. For this reason, it is difficult to apply transducer array to manipulate the beam pattern of waveguide transducers. Here, the self-collimation of phononic crystals is applied to guide an input signal in the waveguide, maintaining the phase difference between active elements at the exit of the waveguide. To achieve this, the lattice parameters of phononic crystals are carefully chosen to exhibit the self-collimation effect at the operating frequency of the waveguide transducer and the beam steering through the proposed waveguide is demonstrated by numerical simulations.
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