Indium phosphide all air-gap Fabry-Pérot filters for near-infrared spectroscopic applications

3rd International School and Conference on Optoelectronics, Photonics, Engineering and Nanostructures (Saint Petersburg OPEN 2016)

Ullah, A.^1 ; Butt, M.A.^2 ; Fomchenkov, S.A.^2,3 ; Khonina, S.N.^2,3

Department of Electronic Engineering, Balochistan University of Information Technology, Engineering and Management Sciences (BUITEMS), Takatu Campus, Airport Road, Quetta

87300, Pakistan^1

Samara State Aerospace University, Moskovskoye Shosse 34, Samara

443086, Russia^2

Image Processing Systems Institute, Russian Academy of Sciences, Molodogvardeyshaya 151, Samara

443001, Russia^3

关键词: Design and implements;    Distributed Bragg reflection;    High index contrast material;    Highly reflecting mirrors;    Low-refractive-index materials;    Near-infrared wavelength;    Noninvasive technique;    Spectrometer detectors;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/741/1/012135/pdf
DOI  :  10.1088/1742-6596/741/1/012135

来源: IOP

【 摘 要 】

Food quality can be characterized by noninvasive techniques such as spectroscopy in the Near Infrared wavelength range. For example, 930 -1450 nm wavelength range can be used to detect diseases and differentiate between meat samples. Miniaturization of such NIR spectrometers is useful for quick and mobile characterization of food samples. Spectrometers can be miniaturized, without compromising the spectral resolution, using Fabry-Pérot (FP) filters consisting of two highly reflecting mirrors with a central cavity in between. The most commonly used mirrors in the design of FP filters are Distributed Bragg Reflections (DBRs) consisting of alternating high and low refractive index material pairs, due to their high reflectivity compared to metal mirrors. However, DBRs have high reflectivity for a selected range of wavelengths known as the stopband of the DBR. This range is usually much smaller than the sensitivity range of the spectrometer detector. Therefore, a bandpass filter is usually required to restrict wavelengths outside the stopband of the FP DBRs. Such bandpass filters are difficult to design and implement. Alternatively, high index contrast materials must be can be used to broaden the stopband width of the FP DBRs. In this work, Indium phosphide all air-gap filters are proposed in conjunction with InGaAs based detectors. The designed filter has a wide stopband covering the entire InGaAs detector sensitivity range. The filter can be tuned in the 950-1450 nm with single mode operation. The designed filter can hence be used for noninvasive meat quality control.