Low-Directivity Quasi-Monochromatic Thermal Radiation From Microcavities Covered by Thin Metal Film

2016 ◽  
Author(s):  
Asaka Kohiyama ◽  
Makoto Shimizu ◽  
Fumitada Iguchi ◽  
Hiroo Yugami
Keyword(s):  
Thin Film ◽  
Numerical Simulation ◽  
Thermal Radiation ◽  
Metal Film ◽  
Solid Angle ◽  
Thin Metal Film ◽  
Q Factor ◽  
High Quality ◽  
Quality Factor Q ◽  
Strong Confinement

Here, closed-end microcavity is proposed in which a semi-transparent metal film was formed atop microcavity. The structure shows weak angular dependence as well as quasi-monochromatic absorptance. Au is employed as material of the cavity walls and the covering thin film. Quasi-monochromatic absorption from the structure is observed in numerical simulation. High quality factor (Q factor) is obtained by strong confinement in the closed-end microcavity. Asymmetric and quasi-monochromatic absorption band with a Q factor of ∼28 at 1.85 μm was observed. This value was about 4-fold larger than that of the open-end microcavity. Additionally, the closed-end microcavity structure filled with SiO2 in cavity exhibits isotropic and quasi-monochromatic thermal radiation over a wide solid angle. This result suggests that both quasi-monochromatic and low-directivity absorptance can be realized by using this configuration.

scholarly journals Narrowband and flexible perfect absorber based on a thin-film nano-resonator incorporating a dielectric overlay

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Chul-Soon Park ◽  
Sang-Shin Lee
Keyword(s):  
Thin Film ◽  
Resonance Condition ◽  
Metal Layer ◽  
High Fidelity ◽  
Perfect Absorber ◽  
Q Factor ◽  
High Quality ◽  
Perfect Absorption ◽  
Narrow Bandwidth ◽  
20 Nm

Abstract We developed a flexible perfect absorber based on a thin-film nano-resonator, which consists of metal–dielectric–metal integrated with a dielectric overlay. The proposed perfect absorber exhibits a high quality (Q-)factor of ~ 33 with a narrow bandwidth of ~ 20 nm in the visible band. The resonance condition hinging on the adoption of a dielectric overlay was comprehensively explored by referring to the absorption spectra as a function of the wavelength and thicknesses of the overlay and metal. The results verified that utilizing a thicker metal layer improved the Q-factor and surface smoothness, while the presence of the overlay allowed for a relaxed tolerance during practical fabrication, in favor of high fidelity with the design. The origin of the perfect absorption pertaining to zero reflection was elucidated by referring to the optical admittance. We also explored a suite of perfect absorbers with varying thicknesses. An angle insensitive performance, which is integral to such a flexible optical device, was experimentally identified. Consequently, the proposed thin-film absorber featured an enhanced Q-factor in conjunction with a wide angle of acceptance. It is anticipated that our absorber can facilitate seminal applications encompassing advanced sensors and absorption filtering devices geared for smart camouflage and stealth.

EFFECT OF SURFACTANT AND SUBSTRATE TEMPERATURE ON THE GROWTH OF Ag FILMS ON A SAPPHIRE SURFACE

1997 ◽  
Vol 04 (02) ◽  
pp. 219-222 ◽  
Author(s):  
T. LEWOWSKI ◽  
P. WIECZOREK
Keyword(s):  
Thin Film ◽  
Substrate Temperature ◽  
Sapphire Substrate ◽  
Metal Film ◽  
Film Growth ◽  
Substrate Surface ◽  
Thin Metal Film ◽  
Thin Film Growth ◽  
Sapphire Surface ◽  
Electrically Conducting

The possibility of modification of the thin film growth on an insulating (sapphire) substrate by using a Ga monolayer as a "surfactant" was studied. We found that the films grown in this way are electrically conducting and can emit photoelectrons at much lower thickness than those deposited on a pure substrate. The surfactant stabilizes the positions of Ag atoms on the substrate surface and inhibits the coalescence of small nuclei into bigger islands, even when the film is annealed to 450 K. This fact may be very important for thin metal film technology.

Thermoelastic Damping Based Design, Sensitivity Study and Demonstration of a Functional Hybrid Gyroscope Resonator for High Quality Factor

2021 ◽  
Vol 29 (1) ◽  
pp. 70-96
Author(s):  
N.G. Sharma ◽  
◽  
Sundararajan T. ◽  
G.S. Singh ◽  
◽  
...  
Keyword(s):  
Thin Film ◽  
Quality Factor ◽  
Sensitivity Study ◽  
Fused Silica ◽  
High Quality Factor ◽  
Q Factor ◽  
Thermoelastic Damping ◽  
High Quality ◽  
Field Problem ◽  
Macro Scale

The most critical element of Hemispherical Resonator Gyroscope (HRG) is the high quality factor (Q-factor) mechanical resonator. This paper discusses the role of thermoelastic damping (TED) on effective Q-factor. Finite element method (FEM) is used to solve this highly coupled field problem involving vibration, solid mechanics, heat transfer and thermodynamics. The major contribution of this paper is the sensitivity analysis of the effect of material property, operating temperature and dimensions to arrive at macro scale resonator configuration. Hybrid hemispherical-cylindrical configuration is proposed by studying the performance parameters such as effective mass and angular gain.The uniqueness of the present work is the sensitivity study of ultra thin film coating (volume fraction of 0.01%), coating variations and different coating configurations. The coating can reduce the Q-factor by a few orders compared to uncoated shell. It has been found that coating material selection and coating configuration are very important factors. Another significance of the present work is the realization and detailed characterization of the hybrid fused silica resonator. Thin film gold coating is done on the 3D surfaces of the realized precision resonator. Detailed coating characterization is carried out using sophisticated instruments. Very fine balancing to the order of a few mHz is achieved after coating. Q-factor measurement of the coated resonator is carried out using LDV and achieved a few millions in the final functional hybrid resonator.

scholarly journals Thin Metal Film Sensors

1985 ◽  
Vol 12 (1) ◽  
pp. 9-32 ◽  
Author(s):  
C. R. Tellier
Keyword(s):  
Thin Film ◽  
Grain Boundary ◽  
Metal Film ◽  
Bulk Diffusion ◽  
Film Structure ◽  
Thin Metal Film ◽  
Thin Metal ◽  
Structural Defects ◽  
Transport Parameters ◽  
Theoretical Predictions

During the last decade some progress have been made in the field of sensors using thin film techniques. In particular thin metal film strain gauges and thin film temperature sensors based on the temperature dependent resistivity of metal are now commonly used. But changes in other transport parameters with various measurands are also useful for the design of metal film sensors. Difficulty arises in thin film techniques when structural defects are frozen in films.Intensive theoretical investigations are carried out to explain the effect of grain-boundary and external surface scatterings on transport parameters. Accordingly the main results are presented to specify the influence of film structure on the sensor performance. The grain-boundary effects are discussed according to applications of metal film sensors. Theoretical predictions are analyzed in terms of sensitivity, thermal stability and long term behavior. But other problems induced by the presence of grain boundaries or point defects are also discussed, in particular problems associated with bulk diffusion, electromigration induced failures or intrinsic stresses.

Effect of Geometric and Material Properties on Thermoelastic Damping (TED) of 3D Hemispherical Inertial Resonator

2016 ◽  
Author(s):  
Jiewen Liu ◽  
Joshua Jaekel ◽  
Dharamdeo Ramdani ◽  
Nabeel Khan ◽  
David S.-K. Ting ◽  
...  
Keyword(s):  
Material Properties ◽  
Design Parameters ◽  
Q Factor ◽  
Thermoelastic Damping ◽  
High Quality ◽  
Hemispherical Shell ◽  
Edge Defects ◽  
Wine Glass ◽  
Quality Factor Q ◽  
Crucial Parameter

High quality factor (Q-factor) is a crucial parameter for the development of precision inertial resonators. Q-factor indicates efficiency of a resonator in retaining its energy during oscillations. This paper explores the effects of different design parameters on Q-factor of a 3D hemispherical (wine-glass) inertial resonator. Thermo-elastic damping (TED) loss mechanisms in a 3D non-inverted wine-glass (hemispherical) shell resonator is systematically investigated and presented in this paper. We investigated TED loss resulting from the effects of hemisphere geometric parameters (such as thickness, height, and radius), mass imbalance, thickness non-uniformity, and edge defects. We used glassblowing to fabricate hemispherical 3D shell resonators. The results presented in this paper can facilitate selecting efficient geometric and material properties for achieving desired Q-factor in 3D inertial resonators. Enhancing the Q-factor in MEMS based 3D resonators can further enable the development of high precision resonators and gyroscopes.

Comparative Studies of Thin-Film Ti-Si and Ti-SiO2 Rapid Thermal Reactions Using the RIP/TEM Technique

1986 ◽  
Vol 74 ◽  
Author(s):  
Menachem Natan
Keyword(s):  
Thin Film ◽  
Electron Microscopy ◽  
Thermal Processing ◽  
Metal Film ◽  
Rapid Thermal Processing ◽  
Nucleation And Growth ◽  
Thin Metal Film ◽  
Processing Temperature ◽  
Thermal Reactions ◽  
Transmission Electron

AbstractOne requirement of self-aligned microelectronics metallization processes is selectivity of reactions, e.g., a deposited, thin metal film must react with Si to form a silicide, yet avoid reaction with SiO2 Rapid thermal processing (RTP) techniques may enhance selectivity by utiliz-ing differences in competing reaction kinetics. In this paper, we apply the RTP/transmission electron microscopy (RTP/TEM) technique to determine processing temperature (T)/time (t) “win-dows” for selective sulicide formation in Ti-Si vs Ti-SiO2 reactions. Free-lying Si/Ti/Si and SiO2/Ti/SiO2 films deposited on electron microscope grids were RTP'd in pairs and immediately examined by TEM. The products of the interfacial reactions, their sequence of appearance, and the T/t conditions for silicide nucleation and growth in each system are described.

Whispering Gallery Mode Microresonators for Biosensing

2012 ◽  
Vol 82 ◽  
pp. 55-63 ◽  
Author(s):  
Silvia Soria ◽  
Simone Berneschi ◽  
Lorenzo Lunelli ◽  
Gualtiero Nunzi Conti ◽  
Laura Pasquardini ◽  
...  
Keyword(s):  
Total Internal Reflection ◽  
Spherical Surface ◽  
High Sensitivity ◽  
Whispering Gallery Mode ◽  
Q Factor ◽  
High Quality ◽  
Whispering Gallery ◽  
Resonance Shift ◽  
Surrounding Environment ◽  
Quality Factor Q

In the field of sensing, WGM microresonators are receiving a growing interest as optical structures suitable for the realization of miniature sensors with high sensitivity. When properly excited, WGM microresonators are able to strongly confine light, by means of total internal reflection,along the equatorial plane near their spherical surface. The corresponding supported resonances show low losses and a high quality factor Q (107-109). These high values of the Q factor make possible the detection of any minute event that occurs on the surface of the spherical microcavity. In fact, any minimum change in the surface of the sphere or in the physical and optical properties of the surrounding environment reduces the Q factor value and modifies the position of the resonancesinside the dielectric microcavity. From a direct measurement of this resonance shift, one can infer the amount of analyte that produces this variation.

scholarly journals High-quality-factor Optical Microresonators Fabricated on Lithium Niobite Thin Film with an Electro-optical Tuning Range Spanning Over One Free Spectral Range

2020 ◽  
Author(s):  
Zhe Wang ◽  
Chaohua Wu ◽  
Zhiwei Fang ◽  
Min Wang ◽  
Jintian Lin ◽  
...  
Keyword(s):  
Thin Film ◽  
Spectral Range ◽  
Tuning Range ◽  
Free Spectral Range ◽  
Resonance Wavelength ◽  
Q Factor ◽  
High Quality ◽  
Electric Voltage ◽  
Optical Microresonators ◽  
Racetrack Resonator

We demonstrate high quality (intrinsic Q factor ~2.8×106) racetrack microresonators fabricated on lithium niobate (LN) thin film with a free spectral range (FSR) of ~86.38 pm. By integrating microelectrodes alongside the two straight arms of the racetrack resonator, the resonance wavelength around the 1550 nm can be red shifted by 92 pm when the electric voltage is raised from -100 V to 100 V. The microresonators of the tuning range spanning over a full FSR is fabricated using photolithography assisted chemo-mechanical etching (photolithography assisted chemo-mechanical etching, PLACE).

Thin Film Herringbone Buckling Patterns

2003 ◽  
Vol 795 ◽  
Author(s):  
Xi Chen ◽  
John W. Hutchinson
Keyword(s):  
Thin Film ◽  
Strain Energy ◽  
Metal Film ◽  
Thin Metal Film ◽  
Thin Metal ◽  
Biaxial Compression ◽  
Compliant Substrate

ABSTRACTThin metal film deposited on compliant substrate undergoes equi-biaxial compression and buckles into a highly ordered herringbone pattern [1,2]. In this study, it is shown that compare with the bifurcation competing modes, the herringbone mode has the lowest strain energy and therefore it is the preferred buckling pattern in the thin film.

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