scholarly journals Broadband High-Efficiency Grating Couplers for Perfectly Vertical Fiber-to-Chip Coupling Enhanced by Fabry-Perot-like Cavity

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 859
Author(s):  
Zan Zhang ◽  
Beiju Huang ◽  
Zanyun Zhang ◽  
Chuantong Cheng ◽  
Bing Bai ◽  
...  
Keyword(s):  
High Efficiency ◽  
Coupling Efficiency ◽  
Light Sources ◽  
Feature Size ◽  
Grating Couplers ◽  
Fabrication Cost ◽  
Fabry Perot ◽  
Dimensional Parameters ◽  
Minimum Feature Size ◽  
Deep Uv

We propose a broadband high-efficiency grating coupler for perfectly vertical fiber-to-chip coupling. The up-reflection is reduced, hence enhanced coupling efficiency is achieved with the help of a Fabry-Perot-like cavity composed of a silicon nitride reflector and the grating itself. With the theory of the Fabry-Perot cavity, the dimensional parameters of the coupler are investigated. With the optimized parameters, up-reflection in the C-band is reduced from 10.6% to 5%, resulting in an enhanced coupling efficiency of 80.3%, with a 1-dB bandwidth of 58 nm, which covers the entire C-band. The minimum feature size of the proposed structure is over 219 nm, which makes our design easy to fabricate through 248 nm deep-UV lithography, and lowers the fabrication cost. The proposed design has potential in efficient and fabrication-tolerant interfacing applications, between off-chip light sources and integrated chips that can be mass-produced.

Isotope shift and hyperfine structure in the atomic spectrum of tin

1973 ◽  
Vol 332 (1588) ◽  
pp. 129-138 ◽  
Keyword(s):  
Stable Isotopes ◽  
Hyperfine Structure ◽  
Nuclear Charge ◽  
Light Sources ◽  
Atomic Spectrum ◽  
Nuclear Charge Distribution ◽  
Fabry Perot ◽  
Self Consistent ◽  
Structure Constants ◽  
Good Agreement

Three lines in the atomic spectrum of tin, λ 3262 Å, λ 3283 Å and λ 6454Å have been studied in emission under high resolution with the use of light sources containing enriched isotopic samples. Results are reported for isotope shifts in these lines for the abundant stable isotopes ( A ≽ 116). Pressure-scanned Fabry–Perot etalons provided the necessary resolution; the spectrograms for λ 6454 Å were recorded and analysed by digital techniques, and for this line hyperfine structure constants required in the interpretation of the data were also evaluated. The results for the three lines are not in good agreement with earlier work, but are shown to be self-consistent by means of a King plot. Their interpretation in terms of the nuclear charge distribution is considered in the following paper.

scholarly journals Optimising apodized grating couplers in a pure SOI platform to −05 dB coupling efficiency

2015 ◽  
Vol 23 (12) ◽  
pp. 16289 ◽  
Author(s):  
Angelo Bozzola ◽  
Lee Carroll ◽  
Dario Gerace ◽  
Ilaria Cristiani ◽  
Lucio Claudio Andreani
Keyword(s):  
Coupling Efficiency ◽  
Grating Couplers

scholarly journals Breaking the Coupling Efficiency–Bandwidth Trade‐Off in Surface Grating Couplers Using Zero‐Order Radiation

2021 ◽  
pp. 2000542
Author(s):  
Alejandro Sánchez‐Postigo ◽  
Robert Halir ◽  
J. Gonzalo Wangüemert‐Pérez ◽  
Alejandro Ortega‐Moñux ◽  
Shurui Wang ◽  
...  
Keyword(s):  
Coupling Efficiency ◽  
Zero Order ◽  
Grating Couplers ◽  
Trade Off ◽  
Surface Grating

Simulation and Characterization of Nanoparticle Thermal Conductivity for a Microscale Selective Laser Sintering System

2021 ◽  
Author(s):  
Joshua Grose ◽  
Obehi G. Dibua ◽  
Dipankar Behera ◽  
Chee S. Foong ◽  
Michael Cullinan
Keyword(s):  
Thermal Conductivity ◽  
Selective Laser Sintering ◽  
Primary Source ◽  
Laser Sintering ◽  
Metal Nanoparticle ◽  
Feature Size ◽  
Cad Models ◽  
Minimum Feature Size ◽  
Geometric Arrangements ◽  
Thermal Simulations

Abstract Additive Manufacturing (AM) technologies are often restricted by the minimum feature size of parts they can repeatably build. The microscale selective laser sintering (μ-SLS) process, which is capable of producing single micron resolution parts, addresses this issue directly. However, the unwanted dissipation of heat within the powder bed of a μ-SLS device during laser sintering is a primary source of error that limits the minimum feature size of the producible parts. A particle scale thermal model is needed to characterize the thermal properties of the nanoparticles undergoing sintering and allow for the prediction of heat affected zones (HAZ) and the improvement of final part quality. Thus, this paper presents a method for the determination of the effective thermal conductivity of metal nanoparticle beds in a microscale selective laser sintering process using finite element simulations in ANSYS. CAD models of nanoparticle groups at various timesteps during sintering are developed from Phase Field Modeling (PFM) output data, and steady state thermal simulations are performed on each group. The complete simulation framework developed in this work is adaptable to particle groups of variable sizes and geometric arrangements. Results from the thermal models are used to estimate the thermal conductivity of the copper nanoparticles as a function of sintering duration.

High-efficiency subwavelength-engineered surface grating couplers in SOI and DSOI

2014 ◽  
Author(s):  
Daniel Benedikovic ◽  
Pavel Cheben ◽  
Jens H. Schmid ◽  
Dan-Xia Xu ◽  
Shurui Wang ◽  
...  
Keyword(s):  
High Efficiency ◽  
Grating Couplers ◽  
Surface Grating

scholarly journals Amplitude electro-optical modulation of radiation by sequences of Fabry-Perot resonators

2020 ◽  
Vol 56 (2) ◽  
pp. 217-223
Author(s):  
V. B. Zalesski ◽  
A. I. Konoiko ◽  
V. M. Kravchenko ◽  
H. S. Kuzmitskaya
Keyword(s):  
Lithium Niobate ◽  
High Efficiency ◽  
Optical Modulation ◽  
Operating Point ◽  
Optical Modulator ◽  
Control Voltage ◽  
Clock Frequency ◽  
Fabry Perot ◽  
In Series ◽  
Light Signals

In this paper, we considered the method of amplitude electro-optical modulation of radiation using sequences of Fabry-Perot resonators based on the transverse electro-optical effect on the example of lithium niobate LiNbO3. With this method, it is possible to significantly reduce the voltage of the control electromagnetic field of the electro-optical amplitude modulator operating in the transmission mode of the light beam while maintaining its high efficiency. The reduction of the control voltage is achieved by increasing the number of Fabry-Perot resonators installed in series and the phase shift relative to the extremum of the transmittance function. This method allows to diminish the duration of the received light signals which leads to an increase in the clock frequency while maintaining a high efficiency of the radiation modulation. Diminishing the duration of light signals is achieved by using separate modulation channels of two sequences of electro-optical Fabry-Perot resonators, the first of which works on the transmission and the second one on the reflection. Increasing the clock frequency at the output of the modulator is achieved by summing the signals coming from several modulation channels. It is shown that the value of the control voltage for an amplitude electro-optical modulator based on a sequence of Fabry-Perot resonators made of lithium niobate LiNbO3, with an operating wavelength of 1.307 microns, can be 4 V in the case when its initial operating point corresponds to the maximum transmittance. The control voltage is 2 V if the initial operating point is shifted in phase relative to the extremum of the transmittance function.

Realization of high-efficiency deep-UV LEDs using transparent p-AlGaN contact layer

2013 ◽  
Vol 10 (11) ◽  
pp. 1521-1524 ◽  
Author(s):  
Noritoshi Maeda ◽  
Hideki Hirayama
Keyword(s):  
High Efficiency ◽  
Contact Layer ◽  
Deep Uv ◽  
Uv Leds

System Design and Energy Management for Indoor Solar Energy Harvesting Under Consideration of Spectral Characteristics of Solar Cells

2013 ◽  
Vol 3 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Christian Viehweger ◽  
Thomas Keutel ◽  
Laura Kasper ◽  
Tim Pfeifer ◽  
Olfa Kanoun
Keyword(s):  
Solar Cells ◽  
Energy Harvesting ◽  
Energy Management ◽  
High Efficiency ◽  
Spectral Characteristics ◽  
Sensor Nodes ◽  
Light Sources ◽  
Wireless Sensor Nodes ◽  
Solar Energy Harvesting ◽  
Difficult Situations

A standardized characterization method for solar cells is only available for outdoor use. For the supply of wireless sensor nodes with energy harvesting also indoor applications are of interest. Without comparable values it is difficult to select the proper cell for defined environmental conditions. Therefore it is necessary to make an investigation on their behavior individually to be able to make a selection. The work presented here shows the characterization of solar cells according to their spectral behavior, the influence of illumination and the usage of this information about the maximum power to design an energy management. Therefore a test structure with a monochromator, different light sources, source measure units and instruments for measuring intensity and spectra has been developed. The measurements help to select the best solar cell out of a repertory for indoor energy harvesting applications. As for indoor applications also the ability to make use of weak light and a high efficiency is important, the energy management has been improved using a dual DC/DC strategy that allows it to make efficient use of solar cells within difficult situations.

High-efficiency fast X-ray imaging detector development at SSRF

2019 ◽  
Vol 26 (5) ◽  
pp. 1631-1637
Author(s):  
Honglan Xie ◽  
Hongxin Luo ◽  
Guohao Du ◽  
Chengqiang Zhao ◽  
Wendong Xu ◽  
...  
Keyword(s):  
High Speed ◽  
High Efficiency ◽  
Sampling Rate ◽  
Coupling Efficiency ◽  
Numerical Aperture ◽  
X Ray ◽  
Temporal Sampling ◽  
X Ray Imaging ◽  
Imaging Detector ◽  
Working Distance

Indirect X-ray imaging detectors consisting of scintillator screens, long-working-distance microscope lenses and scientific high-speed complementary metal-oxide semiconductor (CMOS) cameras are usually used to realize fast X-ray imaging with white-beam synchrotron radiation. However, the detector efficiency is limited by the coupling efficiency of the long-working-distance microscope lenses, which is only about 5%. A long-working-distance microscope lenses system with a large numerical aperture (NA) is designed to increase the coupling efficiency. It offers an NA of 0.5 at 8× magnification. The Mitutoyo long-working-distance microscope lenses system offers an NA of 0.21 at 7.5× magnification. Compared with the Mitutoyo system, the developed long-working-distance microscope lenses system offers about twice the NA and four times the coupling efficiency. In the indirect X-ray imaging detector, a 50 µm-thick LuAG:Ce scintillator matching with the NA, and a high-speed visible-light CMOS FastCAM SAZ Photron camera are used. Test results show that the detector realized fast X-ray imaging with a frame rate of 100000 frames s−1 and fast X-ray microtomography with a temporal sampling rate up to 25 Hz (25 tomograms s−1).

Sign in / Sign up

Export Citation Format

Share Document