Optical-Power Dependence of Gain, Noise, and Bandwidth Characteristics for 850-nm CMOS Silicon Avalanche Photodetectors

Abstract High optical power is considered as the source of failures in passive optical elements. Optical connectors, in particular, have been studied because of the unavoidable exposure of their optical interfaces to environmental issues during insertion and extraction. Cleaning and insertion/extraction procedures are investigated. Evidence for burn-out, depending on the different procedures, calls for new suitable rules for handling during equipment operation and testing.

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Frequency Encoded All Optical Tri-state Logic Gates NOT and NAND Using Semiconductor Optical Amplifier Based Interferometric Switches

Nanoscience &Nanotechnology-Asia ◽

10.2174/2210681209666190620110027 ◽

2020 ◽

Vol 10 (4) ◽

pp. 369-380

Author(s):

K. Maji ◽

K. Mukherjee ◽

A. Raja

Keyword(s):

Semiconductor Optical Amplifier ◽

Extinction Ratio ◽

Optical Power ◽

Logic Gates ◽

Optical Amplifier ◽

All Optical ◽

State Frequency ◽

Spontaneous Noise ◽

First Time ◽

Practical Feasibility

All optical tri-state frequency encoded logic gates NOT and NAND are proposed and numerically investigated using TOAD based interferometric switch for the first time to the best of our knowledge. The optical power spectrum, extinction ratio, contrast ration, and amplified spontaneous noise are calculated to analyze and confirm practical feasibility of the gates. The proposed device works for low switching energy and has high contrast and extinction ratio as indicated in this work.

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Influence of a Thermal Pad on Selected Parameters of Power LEDs

Energies ◽

10.3390/en13143732 ◽

2020 ◽

Vol 13 (14) ◽

pp. 3732

Author(s):

Krzysztof Górecki ◽

Przemysław Ptak ◽

Tomasz Torzewicz ◽

Marcin Janicki

Keyword(s):

Optical Properties ◽

Thermal Resistance ◽

Optical Power ◽

Junction Temperature ◽

Operating Parameters ◽

Cold Plate ◽

Optical Efficiency ◽

Forward Current ◽

Measurement Results ◽

Set Up

This paper is devoted to the analysis of the influence of thermal pads on electric, optical, and thermal parameters of power LEDs. Measurements of parameters, such as thermal resistance, optical efficiency, and optical power, were performed for selected types of power LEDs operating with a thermal pad and without it at different values of the diode forward current and temperature of the cold plate. First, the measurement set-up used in the paper is described in detail. Then, the measurement results obtained for both considered manners of power LED assembly are compared. Some characteristics that illustrate the influence of forward current and temperature of the cold plate on electric, thermal, and optical properties of the tested devices are presented and discussed. It is shown that the use of the thermal pad makes it possible to achieve more advantageous values of operating parameters of the considered semiconductor devices at lower values of their junction temperature, which guarantees an increase in their lifetime.

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Discrete Nonlinear Schrödinger Systems for Periodic Media with Nonlocal Nonlinearity: The Case of Nematic Liquid Crystals

Applied Sciences ◽

10.3390/app11104420 ◽

2021 ◽

Vol 11 (10) ◽

pp. 4420

Author(s):

Panayotis Panayotaros

Keyword(s):

Differential Equation ◽

Infinite System ◽

Linear Part ◽

Optical Power ◽

Explicit Construction ◽

Translation Invariance ◽

Nonlocal Nonlinearity ◽

Wannier Functions ◽

Nonlinear Schrödinger ◽

Nonlinear Schrödinger Systems

We study properties of an infinite system of discrete nonlinear Schrödinger equations that is equivalent to a coupled Schrödinger-elliptic differential equation with periodic coefficients. The differential equation was derived as a model for laser beam propagation in optical waveguide arrays in a nematic liquid crystal substrate and can be relevant to related systems with nonlocal nonlinearities. The infinite system is obtained by expanding the relevant physical quantities in a Wannier function basis associated to a periodic Schrödinger operator appearing in the problem. We show that the model can describe stable beams, and we estimate the optical power at different length scales. The main result of the paper is the Hamiltonian structure of the infinite system, assuming that the Wannier functions are real. We also give an explicit construction of real Wannier functions, and examine translation invariance properties of the linear part of the system in the Wannier basis.

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Global Ocean Studies from CALIOP/CALIPSO by Removing Polarization Crosstalk Effects

Remote Sensing ◽

10.3390/rs13142769 ◽

2021 ◽

Vol 13 (14) ◽

pp. 2769

Author(s):

Xiaomei Lu ◽

Yongxiang Hu ◽

Ali Omar ◽

Rosemary Baize ◽

Mark Vaughan ◽

...

Keyword(s):

Polarization Plane ◽

Optical Power ◽

Satellite Observations ◽

Global Ocean ◽

Reference Plane ◽

Orthogonal Polarization ◽

True Value ◽

Before And After ◽

Oriented Parallel ◽

532 Nm

Recent studies indicate that the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite provides valuable information about ocean phytoplankton distributions. CALIOP’s attenuated backscatter coefficients, measured at 532 nm in receiver channels oriented parallel and perpendicular to the laser’s linear polarization plane, are significantly improved in the Version 4 data product. However, due to non-ideal instrument effects, a small fraction of the backscattered optical power polarized parallel to the receiver polarization reference plane is misdirected into the perpendicular channel, and vice versa. This effect, known as polarization crosstalk, typically causes the measured perpendicular signal to be higher than its true value and the measured parallel signal to be lower than its true value. Therefore, the ocean optical properties derived directly from CALIOP’s measured signals will be biased if the polarization crosstalk effect is not taken into account. This paper presents methods that can be used to estimate the CALIOP crosstalk effects from on-orbit measurements. The global ocean depolarization ratios calculated both before and after removing the crosstalk effects are compared. Using CALIOP crosstalk-corrected signals is highly recommended for all ocean subsurface studies.

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