Mamat Rahmat

Real-time optical sensor based on one dimensional photonic crystals with defects

A previous theoretical study of a finite one-dimensional photonic crystal composed of 12 unit cells with two defects had shown the existence of Photonic Pass Band (PPB) inside the Stop Band, which was suggested as a useful refractive index sensor due to the sensitive variation of PPB with respect to the change of refractive index of defect layer material. We report in this presentation our successful fabrication of a prototype of this system by means of electron beam evaporation equipment in a sample chamber at pressure of 10−3 Pa with BK-7 glass substrate at temperature 573 K. Each of the photonic cells is composed of a high index layer of OS-5 with refractive index of n =3D2.10, and an equal thickness low index layer of MgF2 with n =3D 1.38. In the first defect cell, the high index layer has twice the thickness of the other layers with the low index layer left unchanged, while in the second, defect cell is separated by 6 unit cells, and the first layer is void to be filled with the sample solution. The device was used for measuring the refractive index of sugar solution with concentration range of 20–500 g/L in the real time mode. The result was found to achieve determination coefficient more than 90%. Further measurement performed has demonstrated a result in good agreement with theoretical prediction reported previously.

Fabrication and characterization of NO 2 gas sensor based on one dimensional photonic crystal for measurement of air pollution index

We have fabricated the corresponding photonic crystal (PC) structure by means of electron beam evaporation in a sample chamber at a pressure of 10−3Pa with BK-7 glass substrate at temperatures of 573K. This PC device is applied as a sensor to detect the concentration of NO2 gas dissolved in specific reagent Griess Saltzmann. From spectroscopic measurement it is found that the absorption spectral of the NO2 gas to be in the range of light source wavelength 500–550 nm. Based on this fact, we set up the PCs to admit a photonic pass band (PPB) at a wavelength of 550 nm. To enhance the performance, the device is designed to work on the basis of both absorption and PPB variation phenomena. The experimental results show that the response of the device correlates linearly with the concentration of dissolved NO2 gas and exhibits high sensitivity with coefficient determination of 99%. This sensor is potential to apply in an air pollution index measurement system

Measuring air pollutant standard index (ISPU) with photonics crystal sensor based on wireless sensor network (WSN)

Information systems of air pollutant standard index (ISPU) with photonics crystal sensor which consist of three primary section viz. station as sensor acquisition of air pollutant, server as collecting and data logging, and graphical user interface (GUI) as user facilitating while data acessed has been built. Each station is equipped with five sensors, each of which serves to read the CO gas, SO2, NO2, surface ozone (O3), and dust particles (PM10)[1]. To optimize the performance of the system to be able to retrieve data from areas that are difficult to reach, then the data transmission from the station to the server using wireless communication. Transmitted data is then stored on the server. The saved data can be displayed either in the form of desktop and web applications in realtime and non-realtime.

An integrated optical instrumentation for measuring NO 2 gas using one dimensional photonic crystal

Air pollution is one of main problems in human health, especially in big cities. There are five pollutants material which is indicated as a source of air pollution, one of them is nitrogen oxide (NO2). The proper environmental monitoring system for air pollution management has demanding requirements. We have designed an integrated optical sensor to measure NO2 gas concentration using 1-D photonic crystal. The phenomenon of photonic pass band (PPB) has been used as a frequency filter in liquid concentration measurement. Photonic crystal, LED, and photodiode were designed to operate in NO2 absorption spectra that are in the range between 557.23 and 558.01 nm. The NO2 gas concentration is inversely proportional to intensity of peak PPB spectra. We built electronic signal conditioning circuit which is consisting of: current to voltage converter, voltage follower, active low pass filter, and instrumentation amplifier, to get an appropriate signal. The experimental results show that our optical integrated instrumentation is able to measure NO2 gas concentration, while requiring a filtering circuit addition because of the presence of internal noise.