Determination of Reactive RF-Sputtering Parameters for Fabrication of SiOx Films With Specified Refractive Index, for Highly Reflective SiOx Distributed Bragg Reflector

A conductive DBR electrode fabricated using the single Indium tin oxide (ITO) conductive material is proposed. The high refractive index of the dense ITO film was achieved by RF sputtering at room temperature and the porous ITO film with low refractive index was prepared by applying supercritical CO2(SCCO2) treatment at 60 °C on gel-coated ITO thin films. The index contrast of the ITO bilayers was higher than 0.5 at a wavelength of 550 nm. In addition, small deviations on the optical thickness of the ITO bilayers were observed during the DBR stacking processes. For the DBR comprising 4 periods ITO bilayers, the reflectance and sheet resistance of 72.8% and 35 Ω/ were achieved.

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Tunability of Distributed Bragg-Reflector Laser by Modulating Refractive Index in Corrugated Waveguide

Japanese Journal of Applied Physics ◽

10.1143/jjap.16.1501 ◽

1977 ◽

Vol 16 (8) ◽

pp. 1501-1502 ◽

Cited By ~ 13

Author(s):

Masahiro Okuda ◽

Kiyoshi Onaka

Keyword(s):

Refractive Index ◽

Bragg Reflector ◽

Corrugated Waveguide ◽

Distributed Bragg Reflector

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OMNI-DIRECTIONAL REFLECTOR USING A LOW REFRACTIVE INDEX MATERIAL

International Journal of High Speed Electronics and Systems ◽

10.1142/s0129156404002740 ◽

2004 ◽

Vol 14 (03) ◽

pp. 726-731

Author(s):

J.-Q. XI ◽

MANAS OJHA ◽

WOOJIN CHO ◽

TH. GESSMANN ◽

E. F. SCHUBERT ◽

...

Keyword(s):

Refractive Index ◽

Dielectric Material ◽

Metal Layer ◽

Transverse Magnetic ◽

Bragg Reflector ◽

Light Extraction Efficiency ◽

Distributed Bragg Reflector ◽

Triple Layer ◽

Quarter Wavelength ◽

Low Refractive Index

Triple-layer omni-directional reflectors (ODRs) consisting of a semiconductor, a transparent quarter-wavelength dielectric layer and metal layer have high reflectivities at all angles of incidence. In this paper, triple-layer ODRs are demonstrated that incorporate nanoporous SiO 2, a novel low-refractive-index (low-n) material with refractive indices n ≪ 1.46 as well as dense SiO 2 (n = 1.46). GaP and Ag serve as the semiconductor and metal layer materials, respectively. An angle-integrated transverse electric (TE) mode reflectivity of R avg | TE = 99.9 % and transverse magnetic (TM) mode reflectivity R avg | TM = 98.9 % are calculated for the triple-layer ODRs employing nanoporous SiO 2. Reflectivity measurements, including the angular dependence of R, are presented. Novel hybrid ODRs consisting of semiconductor, a several micron thick low-n dielectric material layer, a distributed Bragg reflector (DBR) and metal layer have outstanding reflectivities for all incident angles. GaP and Ag serve as the semiconductor and metal layer, respectively. Nanoporous SiO 2 is used as the low-n material. TiO 2 and dense SiO 2 serve as the DBR materials. The angle-intergrated reflectivities of the TE and TM modes are calculated to be larger than 99.9 % for the hybrid ODRs. The results indicate the great potential of the ODRs for light-emitting diodes with high light extraction efficiency.

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Optical Thin Films with Very Low Refractive Index and Their Application in Photonics Devices

MRS Proceedings ◽

10.1557/proc-0901-ra11-29-rb11-29 ◽

2005 ◽

Vol 901 ◽

Author(s):

Jingqun Xi ◽

Jong Kyu Kim ◽

Dexian Ye ◽

Jasbir S. Juneja ◽

T.-M. Lu ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Refractive Index ◽

Incident Angle ◽

Columnar Structure ◽

Bragg Reflector ◽

Single Pair ◽

Scanning Electron Micrographs ◽

Distributed Bragg Reflector ◽

Low Refractive Index

AbstractThe refractive index contrast in dielectric multilayer structures, optical resonators and photonic crystals is an important figure of merit, which creates a strong demand for high quality thin films with a very low refractive index. SiO2 nano-rod layers with low refractive indices n = 1.08, the lowest ever reported in thin-film materials, is grown by oblique-angle e-beam deposition of SiO2 with vapor incident angle 85 degree. Scanning electron micrographs reveal a highly porous columnar structure of the low-refractive-index (low-n) film. The gap between the SiO2 nano-rods is ≤50 nm, i.e. much smaller than the wavelength of visible light, and thus sufficiently small to make scattering very small. Optical micrographs of the low-n film deposited on a Si substrate reveal a uniform specular film with no apparent scattering. The unprecedented low index of the SiO2 nano-rod layer is confirmed by both ellipsometry measurements and thin film interference measurements. A single-pair distributed Bragg reflector (DBR) employing the SiO2 nano-rod layer is demonstrated to have enhanced reflectivity, showing the great potential of low-n films for applications in photonic structures and devices.

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Extended bound states in the continuum in a one-dimensional grating implemented on a distributed Bragg reflector

Nanophotonics ◽

10.1515/nanoph-2021-0478 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Emilia Pruszyńska-Karbownik ◽

Mikołaj Janczak ◽

Tomasz Czyszanowski

Keyword(s):

Refractive Index ◽

Bound States ◽

High Refractive Index ◽

Bragg Reflector ◽

Distributed Bragg Reflector ◽

Optical Cavities ◽

One Dimensional ◽

Optical Modes ◽

High Degree ◽

The Continuum

Abstract Bound states in the continuum (BICs) are observed in optical cavities composed of a high refractive index periodic structure embedded in significantly lower refractive index surroundings, enabling vertical confinement of the grating modes. Here, we propose a vertically nonsymmetric configuration, implemented on a high refractive index bulk substrate with a one-dimensional grating positioned on a distributed Bragg reflector (DBR). In this configuration, the grating modes are leaky, which could prohibit the creation of a BIC if the grating was implemented on uniform substrate. However, the judiciously designed DBR on which the grating is implemented reflects nonzero diffraction orders induced by the grating. We found that the laterally antisymmetric optical modes located at the center of the Brillouin zone of this structure create BICs that are robust against changes in the grating parameters, as long as the DBR reflects the diffraction orders. The configuration enables a high degree of design freedom, facilitating the realization of very high quality factor cavities in conventional all-semiconductor technology.

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