A photonic integrated circuit (PIC) is a lightweight, compact alternative to bulk optics. The Fibered Imager foR a Single Telescope (FIRST) instrument, is a spectro-interferometer performing pupil remapping and design...
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ISBN:
(纸本)9781510675131;9781510675148
A photonic integrated circuit (PIC) is a lightweight, compact alternative to bulk optics. The Fibered Imager foR a Single Telescope (FIRST) instrument, is a spectro-interferometer performing pupil remapping and designed to operate in the 600 to 800nm visible wavelength range. It is installed on the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument's platform at the Subaru telescope. In the integrated optical version of FIRST (FIRST PIC), the interferometric combination of the beams occurs by the pairwise combination of five sub-apertures to achieve 20 baselines. This paper introduces a PIC design with novel components for splitting and pairwise coupling the light for FIRST PIC, fabricated and packaged by LioniX International. A high index difference between the waveguide fundamental mode and cladding material was selected to allow compact circuits with prospects of increasing the number of combined sub-apertures with designs of much greater complexity. The high confinement waveguides were simulated to produce approximately 50% injection loss, a tapering system in both height and width to a low confinement waveguide at the PIC interface ameliorated the loss. The optimised throughput prediction is estimated at 80%. Standard couplers and splitters are expected to have high losses due to fabrication tolerances, and due to the high confinement, standard couplers' performance is highly dependent on the wavelength. Presented here are novel component designs to replace them. Tapered directional couplers, which maintain an acceptable coupling ratio over the entire bandwidth, and tri-couplers, with higher throughput than conventional splitters but high intolerance to fabrication issues, were designed and fabricated for this purpose. The designs and individual experimental verification will be discussed, focusing on polarization and wavelength response. The full combination of components was used to create a five sub-aperture combiner for FIRST. Cross-talk betwe
We theoretically demonstrate a few novel small-footprint and broadband integrated photonic devices based on optical waveguides patterned with phased antenna arrays. These devices include waveguide mode converters, pol...
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ISBN:
(纸本)9781557529688
We theoretically demonstrate a few novel small-footprint and broadband integrated photonic devices based on optical waveguides patterned with phased antenna arrays. These devices include waveguide mode converters, polarization rotators, perfect absorbers, and optical power diodes.
A methodology for the generation of a multi-mode multi-port aperture antenna is proposed based on the selective excitation of magnetic current modes. The magnetic current modes are determined based on the analytical s...
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ISBN:
(纸本)9788831299091;9798350394436
A methodology for the generation of a multi-mode multi-port aperture antenna is proposed based on the selective excitation of magnetic current modes. The magnetic current modes are determined based on the analytical solution of wave-guide modes with the same aperture dimensions. An excitation technique for the modal magnetic aperture currents is shown by placing multiple ports within the aperture. Guidelines for the port placement within the aperture are given based on the magnetic current distribution. Further, a feeding network topology is proposed to selectively excite the magnetic current modes of the aperture. The theory is evaluated and validated by an analysis of the radiation patterns of the individual antenna ports as well as an investigation of the envelope correlation coefficient of the radiation patterns. It is shown that the excited far-fields are orthogonal, which confirms the claimed selective excitation of the magnetic current modes.
A previously presented prototype of a microwave oil/water ratio measurement system for geological applications has provided positive and applicable results in a commercial flow loop test. The prototype is a two-port c...
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ISBN:
(纸本)9798331517854;9781736235164
A previously presented prototype of a microwave oil/water ratio measurement system for geological applications has provided positive and applicable results in a commercial flow loop test. The prototype is a two-port circular waveguide traversed by a pipe. Both waveguides face each other on opposite sides of the pipe and are filled with dielectric material, which is molded to match the inside walls of the pipe. For maximizing transmission, avoiding higher order modes, the microwave waveguides in the system are designed with a diameter slightly smaller to that of the pipe. To expand the applications of the current system, a more thorough understanding of the waveguide propagation on a transversal pipe system and its limitations is needed. However, the complexity of the geometry makes the problem analytically intractable. Three dimensional simulations for transversal pipes geometries were performed in COMSOL 6.2 from 1 GHz to 4 GHz. Initial numerical results show waveguide mode propagation in the pipe at lower frequencies and pipe mode propagation at frequencies passed the optimum transmission frequency where the horizontally propagating waveguide/pipe mode wavelength are slightly smaller than the diameter of the waveguide/pipe intersection. Higher order modes can be seen in both waveguide and pipe at frequencies above 2.5 GHz.
A loaded waveguide antenna has been designed, manufactured, and tested to explore potential applications in ocean observation projects. This antenna can operate under high pressure and attenuation in the deep sea with...
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ISBN:
(纸本)9798350369908;9798350369915
A loaded waveguide antenna has been designed, manufactured, and tested to explore potential applications in ocean observation projects. This antenna can operate under high pressure and attenuation in the deep sea with simple techniques to adjust the operating frequency.
Gallium nitride (GaN) ultraviolet (UV) laser diodes (LDs) show tremendous promise for optical communications, data storage, and medical applications due to their compact size and higher efficiency compared to gas lase...
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ISBN:
(纸本)9781510670334;9781510670327
Gallium nitride (GaN) ultraviolet (UV) laser diodes (LDs) show tremendous promise for optical communications, data storage, and medical applications due to their compact size and higher efficiency compared to gas lasers. Typically, GaN UV LDs utilize a symmetric waveguide structure surrounding a multiple quantum well (MQW) active region for optical confinement. By increasing the thickness of these waveguides, device performance can be enhanced by reducing absorption losses. However, thin waveguides offer decreased carrier losses and improved electrical performance. These two competing effects can be balanced through the use of an asymmetric waveguide structure, composed of a thin upper waveguide and thick lower waveguide, in order to minimize both carrier (hole) losses as well as optical losses. Here, we demonstrated an edge-emitting ridge waveguide UV GaN LD emitting at similar to 392 nm. Mirror facets were fabricated through reactive ion etch and potassium hydroxide wet etch. These LD structures with InGaN/GaN MQWs and AlGaN cladding layers were grown via metalorganic chemical vapor deposition on a patterned sapphire substrate and utilize an asymmetric 100 nm thick upper unintentionally doped GaN (uGaN) waveguide and 500 nm thick lower uGaN waveguide structure. We have successfully demonstrated a LD device with 1000 mu m cavity length with a lasing threshold of 2.2 A, and 111.8 mW per facet peak optical output power with a differential efficiency of 3%. This demonstration paves the way for GaN LDs with improved differential efficiency at high current densities through the use of optimized asymmetric waveguide structures.
We demonstrate an in situ, non-invasive measurement method to ensure stable manufacturing and quality control of integrated waveguides. This method assumes that the scattered light from a waveguide is proportional to ...
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ISBN:
(纸本)9781510678781;9781510678798
We demonstrate an in situ, non-invasive measurement method to ensure stable manufacturing and quality control of integrated waveguides. This method assumes that the scattered light from a waveguide is proportional to the propagating light inside the waveguide. Consequently, we can estimate the waveguide losses by measuring the scattered light along the waveguide. We compare this newly demonstrated measurement method with state-of-the-art methods, including Fabry-Perot interferometry, Mach-Zehnder Interferometry, ring resonator interferometry, and the cut-back method. To validate our measurement method's working principle, we fabricated multiple amorphous silicon waveguides and characterized them using both, the presented and the cut-back method. Both methods yielded comparable results, indicating losses of around 1 dB/cm. For further investigation, multiple measurements of the same sample were conducted, resulting in a standard deviation of 0.29 dB/cm to 0.60 dB/cm. These initial standard deviations are sufficient to verify the presented measurement method. However, we want to emphasize that the main source of these deviations is due to the used measurement setup, indicating that the method has potential for improvement. Nevertheless, we have demonstrated that an in situ, non-invasive measurement of integrated waveguide losses is possible.
The authors studied the transmission performance for orthogonal polarization fundamental modes in a dielectric silicon terahertz waveguide for doubling the data rate. The maximum data rate of practical error-free cond...
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The authors studied the transmission performance for orthogonal polarization fundamental modes in a dielectric silicon terahertz waveguide for doubling the data rate. The maximum data rate of practical error-free condition (bit-error rate < 10(-11)) for both polarizations is comparable over 20 Gbit/s under on-off keying modulation at 0.3-THz band.
This paper discusses a new approach to the joining of Ku-band waveguides made of high-strength crack-sensitive aluminum alloys, A16061 and A16063. Using a pulsed Nd:YAG laser system in combination with a pulsed wire f...
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ISBN:
(纸本)9781479987672
This paper discusses a new approach to the joining of Ku-band waveguides made of high-strength crack-sensitive aluminum alloys, A16061 and A16063. Using a pulsed Nd:YAG laser system in combination with a pulsed wire feed drive, rectangular waveguide segments are welded. The results clearly show the potential to employ welding as a substitute to conventional brazing and soldering processes: the electrical and mechanical performances are close to the ones of a milled waveguide. Furthermore, the presented welding process is completely automated.
GeTe4 waveguides were designed and fabricated on silicon substrates with a ZnSe isolation layer. GeTe4 has a refractive index of 3.25 at a wavelength of 9 mu m and a lower refractive index isolation layer is needed to...
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ISBN:
(纸本)9781628417753
GeTe4 waveguides were designed and fabricated on silicon substrates with a ZnSe isolation layer. GeTe4 has a refractive index of 3.25 at a wavelength of 9 mu m and a lower refractive index isolation layer is needed to realise waveguides on silicon. Numerical modelling was carried out to calculate the thickness of the isolation layer (ZnSe, refractive index similar to 2.4) required to achieve low loss waveguides. For a loss between 0.1 and 1.0 dB/cm it was found that a similar to 4 mu m thick ZnSe film is required at a wavelength of 9 mu m. ZnSe thin films were deposited on silicon, GeTe4 waveguides were fabricated by lift-off technique and were characterised for mid-infrared waveguiding.
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