Design of non-polarizing thin film edge filters

The separation between s- and p-polarization components invariably affects thin film edge filters used for tilted incidence and is a difficult problem for many applications, especially for optical communication. This paper presents a novel design method to obtain edge filters with non-polarization at incidence angle of 45°. The polarization separation at 50% trans-mittance for a long-wave-pass filter and a short-wave-pass filter is 0.3 nm and 0.1 nm respectively. The design method is based on a broadband Fabry-Perot thin-film interference filter in which the higher or lower interference band at both sides of the main transmittance peak can be used for initial design of long-wave-pass filter or short-wave-pass filter and then can be refined to reduce the transmittance ripples. The spacer 2H2L2H or 2L2H2L of the filter is usually taken. Moreover, the method for expanding the bandwidth of rejection and transmission is explained. The bandwidth of 200 nm for both rejection region and transmission band is obtained at wavelength 1550 nm. In this way, the long-wave-pass and short-wave-pass edge filters with zero separation between two polarization components can easily be fabricated.

Contrast Enhancement Based Image Detection Using Edge Preserved Key Pixel Point Filtering

In existing methods for segmented images,either edge point extraction or preservation of edges,compromising contrast images is so sensitive to noise.The Degeneration Threshold Image Detection(DTID)framework has been proposed to improve the contrast of edge filtered images.Initially,DTID uses a Rapid Bilateral Filtering process for filtering edges of contrast images.This filter decomposes input images into base layers in the DTID framework.With minimal filtering time,Rapid Bilateral Filtering handles high dynamic contrast images for smoothening edge preservation.In the DTID framework,Rapid Bilateral Filtering with Shift-Invariant Base Pass Domain Filter is insensitive to noise.This Shift-Invariant Filtering estimates value across edges for removing outliers(i.e.,noise preserving base layers of the contrast image).The intensity values are calculated in the base layer of the contrast image for accurately detecting nearby spatial locations using Shift-Invariant base Pass Domain Filter(SIDF).At last,Affine Planar Transformation is applied to detect edge filtered contrast images in the DTID framework for attaining a high quality of the image.It normalizes the translation and rotation of images.With this,Degeneration Threshold Image Detection maximizes average contrast enhancement quality and performs an experimental evaluation of factors such as detection accuracy,rate,and filtering time on contrast images.Experimental analysis shows that the DTID framework reduces the filtering time taken on contrast images by 54%and improves average contrast enhancement quality by 27%compared to GUMA,HMRF,SWT,and EHS.It provides better performance on the enhancement of average contrast enhancement quality by 28%,detection accuracy rate by 26%,and reduction in filtering time taken on contrast images by 30%compared to state-of-art methods.

A Novel Method of Edge Filter Linear Demodulation Using Long Period Grating in Fiber Sensor System

A novel method of linear demodulation based on edge filter is presented. An experimental system is built up in which LPG is used as the edge filter. We achieve linear demodulation with a bandwidth of 5nm.

Study on 3D CFBG Vibration Sensor and Its Application

A novel variety of three dimensional （3D） vibration sensor based on chirped fiber Bragg grating （CFBG） is developed to measure 3D vibration in the mechanical equipment field. The sensor is composed of three independent vibration sensing units. Each unit uses double matched chirped gratings as sensing elements, and the sensing signal is processed by the edge filtering demodulation method. The structure and principle of the sensor are theoretically analyzed, and its performances are obtained from some experiments and the results are as follows： operating frequency range of the sensor is 10Hz - 500Hz; acceleration measurement range is 2m.s-2 - 30m.s-2; sensitivity is about 70 mV/m.s-2; crosstalk coefficient is greater than 22 dB; self-compensation for temperature is available. Eventually the sensor is applied to monitor the vibration state of radiation pump. Seen from its experiments and applications, the sensor has good sensing performances, which can meet a certain requirement for some engineering measurement.

Usage of Simulated Annealing Algorithm in Design of Optical Thin Film

Simulated annealing algorithm is a mathematic model,which imitates the physical process of annealing. And optical thin film is widely used in many industry.Its design is difficult and can be regarded as an optimization problem.In this paper,we use the simulated annealing algorithm to design an edge filter,which is composed of 20 dielectric thin film layers with TiO2 and SiO2.The simulated annealing algorithm is a very robust algorithm for optical thin film design.

Beam multiplexing of diode laser arrays

Design and experimental studies on the wavelength multiplexing and polarization multiplexing of diode laser arrays were carried out. First, the structure of a A1GalnAs/GaAs/AIGaAs quantum well under compressive strain was used because the characteristic of wavelength was easier to adjust. We obtained diode laser arrays lasing in five different wavelengths, about 760 nm, 800 nm, 860 nm, 930 nm, and 976 nm. At the same time, four edge filters were designed, and an experimental study on the beam multiplexing of diode laser arrays was carried out. Second, two beams with different polarization states were composited using a half wave plate and a polarizing beam-splitter prism. After that, the beam focusing system was designed. Ultimately, ten beams of diode laser arrays in five wavelengths and two polarization states were composited, the total output power was 196 W and the overall efficiency was 76%. The size of the output focus spot was 144 × 1330μm2, and the power density of the focused light was as high as 1.02 ×105 W/cm2. Compared with a single diode laser array, the power density of the composite beam was improved by 4.3 times.