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Subwavelength Structured Photonic Integrated Devices for Near- and Mid-infrared Applications.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Subwavelength Structured Photonic Integrated Devices for Near- and Mid-infrared Applications./
Author:	Zhou, Wen.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2018,
Description:	261 p.
Notes:	Source: Dissertations Abstracts International, Volume: 80-06, Section: B.
Contained By:	Dissertations Abstracts International80-06B.
Subject:	Electrical engineering. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=11012271
ISBN:	9780438659735

Subwavelength Structured Photonic Integrated Devices for Near- and Mid-infrared Applications.
Zhou, Wen.

Subwavelength Structured Photonic Integrated Devices for Near- and Mid-infrared Applications. - Ann Arbor : ProQuest Dissertations & Theses, 2018 - 261 p.

Source: Dissertations Abstracts International, Volume: 80-06, Section: B.

Thesis (Ph.D.)--The Chinese University of Hong Kong (Hong Kong), 2018.

This item must not be sold to any third party vendors.

Tremendous progress of the group-IV photonics from the early 2000s has shown that light can be manipulated at the subwavelength scale with judiciously designed periodic and aperiodic photonic materials and give rise to unprecedented optical properties. In this thesis, hyperuniform disordered photonic structure (HUDPS) and subwavelength grating (SWG) are exploited for developing subwavelength-structured photonic integrated circuits (PICs) and devices with overall improved performances and advanced functions compared with those of the conventional platforms for near- and mid-infrared (IR) applications in polarization controlling, light coupling, wave guiding, and resonating. HUDPS with the short-range order and statistical isotropy are a new class of photonic material. Photon transportation in a HUDPS exhibits behaviors of scattering, diffusion, and Bragg reflection due to the photonic bandgap (PBG) effect, which has special characters of isotropy, large bandwidth, and polarization dependence. The silicon-on-insulator (SOI) PICs based on HUDPS are proposed as a new waveguide platform for polarization controlling with overall improved performances compared with those of the integrated polarizers based on the periodic photonic crystals (PhCs). HUDPS polarizers were demonstrated with one of the largest bandwidths of 98 nm when extinction ratio is larger than 30 dB and one of the shortest device lengths of 8 μm. An average excess loss of the transmitted TM mode is 1.7 dB. The adverse back reflection can be reduced to 81.8%. HUDPS polarizers are tolerant to fabrication errors due to disordered nature. Performances can be well maintained with width variations between -25 nm and 20 nm. SWGs are periodic structures with a pitch smaller than the working wavelength to avoid diffraction effects. Working in the subwavelength regime, SWG can be treated as a dispersion-tailorable and birefringent metamaterial with a refractive index (RI) defined by the Rytov's effective-medium theory. The best broadband focusing subwavelength grating coupler (FSWGC) has a 1-dB bandwidth of ~100 nm, which poses a tough challenge for simultaneously coupling widely separated dual-wavelength bands from a SMF into a PIC for wavelength-division-multiplexing (WDM) applications. Based on the composited SWGs, a practical four-step methodology is proposed for designing the TE-mode SOI FSWGCs with tailorable dual spectral peaks diffracted at the same angle in near-IR. Fabricated FSWGCs were measured with spectral peaks at (1486.0, 1594.5) nm and (1481.5, 1661.5) nm with coupling efficiencies of (18.3%, 20.1%) and (14.5%, 17.5%), 3-dB bandwidths of (55.0, 30.5) nm and (44.0, >39.5) nm, respectively. As a new type of surface grating coupler, it will greatly facilitate direct coupling between the fiber-optic links and on-chip WDM linear and nonlinear systems. In mid-IR region, Ge has an ultrawide spectral range of transparency (2-V15 μm). Mid-IR Ge grating couplers based on Ge-on-Si and Ge-on-SOI platforms suffer from high back-reflection, low directionality, and low coupling strength, due to a small index contrast between Ge and Si, and limited spectral range of transparency (< 8 μm) due to absorption of Si. These limitations are overcome in the air-cladding suspended Ge FSWGCs, which were demonstrated with one of the highest coupling efficiencies of -11 dB and a 1-dB bandwidth of ~58 nm at the center wavelength of 2370 nm. Based on the SWG metamaterial, a fully suspended slot waveguide (FSSW) platform was proposed to make full use of the spectral range of transparency of Si and to enhance light-matter interfacing due to 42% of the modal power in ambient, which is larger than that in the slot waveguides sitting on buried oxide (BOX). SWG performs triple functions in (i) diffraction-free index guiding as an in-plane waveguide cladding, (ii) deformation-free mechanical supporting of the slotted waveguide cores and devices, and (iii) wet etching of BOX using a hydrogen fluoride solution. With an air-cladding geometry, the spectral range of transparency of the FSSW platform covers 2.0-8.0 μm. Theoretically calculated RI sensitivity is 1.1. Low-loss guiding (2.8 dB/cm) and bending (0.15 dB/90°) of the Bloch-Floquet mode were demonstrated in the asymmetric FSSWs. Loaded and intrinsic optical Q factors of the FSSW racetrack resonators are 8550 and 12600, respectively. An average conversion efficiency of a strip-to-slot mode converter is 95.4% over a bandwidth of 170 nm. A coupling coefficient of a sidewall Bragg grating is 2.1 x 104 m-1. In addition, fully suspended nanophotonic waveguide (FSNW) ring resonators were measured with a loaded Q factor of 40,600 and tailorable operational bandwidth by engineering dispersion of the coupling coefficient. The broadband and low-loss FSSW and FSNW platforms are promising candidates for long-range and cavity-enhanced mid-IR light-analyte interaction.

ISBN: 9780438659735Subjects--Topical Terms:

649834
Electrical engineering.

Subwavelength Structured Photonic Integrated Devices for Near- and Mid-infrared Applications.
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245 1 0 $a Subwavelength Structured Photonic Integrated Devices for Near- and Mid-infrared Applications.
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300 $a 261 p.
500 $a Source: Dissertations Abstracts International, Volume: 80-06, Section: B.
500 $a Publisher info.: Dissertation/Thesis.
502 $a Thesis (Ph.D.)--The Chinese University of Hong Kong (Hong Kong), 2018.
506 $a This item must not be sold to any third party vendors.
506 $a This item must not be added to any third party search indexes.
520 $a Tremendous progress of the group-IV photonics from the early 2000s has shown that light can be manipulated at the subwavelength scale with judiciously designed periodic and aperiodic photonic materials and give rise to unprecedented optical properties. In this thesis, hyperuniform disordered photonic structure (HUDPS) and subwavelength grating (SWG) are exploited for developing subwavelength-structured photonic integrated circuits (PICs) and devices with overall improved performances and advanced functions compared with those of the conventional platforms for near- and mid-infrared (IR) applications in polarization controlling, light coupling, wave guiding, and resonating. HUDPS with the short-range order and statistical isotropy are a new class of photonic material. Photon transportation in a HUDPS exhibits behaviors of scattering, diffusion, and Bragg reflection due to the photonic bandgap (PBG) effect, which has special characters of isotropy, large bandwidth, and polarization dependence. The silicon-on-insulator (SOI) PICs based on HUDPS are proposed as a new waveguide platform for polarization controlling with overall improved performances compared with those of the integrated polarizers based on the periodic photonic crystals (PhCs). HUDPS polarizers were demonstrated with one of the largest bandwidths of 98 nm when extinction ratio is larger than 30 dB and one of the shortest device lengths of 8 μm. An average excess loss of the transmitted TM mode is 1.7 dB. The adverse back reflection can be reduced to 81.8%. HUDPS polarizers are tolerant to fabrication errors due to disordered nature. Performances can be well maintained with width variations between -25 nm and 20 nm. SWGs are periodic structures with a pitch smaller than the working wavelength to avoid diffraction effects. Working in the subwavelength regime, SWG can be treated as a dispersion-tailorable and birefringent metamaterial with a refractive index (RI) defined by the Rytov's effective-medium theory. The best broadband focusing subwavelength grating coupler (FSWGC) has a 1-dB bandwidth of ~100 nm, which poses a tough challenge for simultaneously coupling widely separated dual-wavelength bands from a SMF into a PIC for wavelength-division-multiplexing (WDM) applications. Based on the composited SWGs, a practical four-step methodology is proposed for designing the TE-mode SOI FSWGCs with tailorable dual spectral peaks diffracted at the same angle in near-IR. Fabricated FSWGCs were measured with spectral peaks at (1486.0, 1594.5) nm and (1481.5, 1661.5) nm with coupling efficiencies of (18.3%, 20.1%) and (14.5%, 17.5%), 3-dB bandwidths of (55.0, 30.5) nm and (44.0, >39.5) nm, respectively. As a new type of surface grating coupler, it will greatly facilitate direct coupling between the fiber-optic links and on-chip WDM linear and nonlinear systems. In mid-IR region, Ge has an ultrawide spectral range of transparency (2-V15 μm). Mid-IR Ge grating couplers based on Ge-on-Si and Ge-on-SOI platforms suffer from high back-reflection, low directionality, and low coupling strength, due to a small index contrast between Ge and Si, and limited spectral range of transparency (< 8 μm) due to absorption of Si. These limitations are overcome in the air-cladding suspended Ge FSWGCs, which were demonstrated with one of the highest coupling efficiencies of -11 dB and a 1-dB bandwidth of ~58 nm at the center wavelength of 2370 nm. Based on the SWG metamaterial, a fully suspended slot waveguide (FSSW) platform was proposed to make full use of the spectral range of transparency of Si and to enhance light-matter interfacing due to 42% of the modal power in ambient, which is larger than that in the slot waveguides sitting on buried oxide (BOX). SWG performs triple functions in (i) diffraction-free index guiding as an in-plane waveguide cladding, (ii) deformation-free mechanical supporting of the slotted waveguide cores and devices, and (iii) wet etching of BOX using a hydrogen fluoride solution. With an air-cladding geometry, the spectral range of transparency of the FSSW platform covers 2.0-8.0 μm. Theoretically calculated RI sensitivity is 1.1. Low-loss guiding (2.8 dB/cm) and bending (0.15 dB/90°) of the Bloch-Floquet mode were demonstrated in the asymmetric FSSWs. Loaded and intrinsic optical Q factors of the FSSW racetrack resonators are 8550 and 12600, respectively. An average conversion efficiency of a strip-to-slot mode converter is 95.4% over a bandwidth of 170 nm. A coupling coefficient of a sidewall Bragg grating is 2.1 x 104 m-1. In addition, fully suspended nanophotonic waveguide (FSNW) ring resonators were measured with a loaded Q factor of 40,600 and tailorable operational bandwidth by engineering dispersion of the coupling coefficient. The broadband and low-loss FSSW and FSNW platforms are promising candidates for long-range and cavity-enhanced mid-IR light-analyte interaction.
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710 2 $a The Chinese University of Hong Kong (Hong Kong). $b Electronic Engineering. $3 2094192
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