Photonic crystal gas sensors (original) (raw)
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Macroporous silicon photonic crystals for gas sensing
2013 Spanish Conference on Electron Devices, 2013
a) b) Figure 1. 3-D macroporous silicon samples fabricated in our laboratory. Pores are modulated with a sine-like profile. B) image shows a plane defect in the structure: missing "bump".
Photonic crystal cavity based gas sensor
Applied Physics Letters, 2008
We have studied the response of a photonic crystal cavity to changes of the ambient refractive index. Transmission measurements of the cavity under different gaseous environments and pressures showed a linear dependence of the resonance wavelength on the refractive index of the ambient gas. A change of the refractive index by 10 -4 leads to a shift of the resonace by 8 pm, which is readily detectable due to the high quality factor of the cavity. The observed wavelength shifts agree well with finite-difference time domain simulations of the cavity.
Miniature infrared gas sensors using photonic crystals
Journal of Applied Physics, 2011
We present an optical gas sensor based on the classical nondispersive infrared technique using ultracompact photonic crystal gas cells. The ultracompact device is conceptually based on low group velocities inside a photonic crystal gas cell and low-reflectivity antireflection layers coupling light into the device. Experimentally, an enhancement of the CO 2 infrared absorption by a factor of 2.6 to 3.5 as compared to an empty cell, due to slow light inside a 2D silicon photonic crystal gas cell, was observed; this is in excellent agreement with numerical simulations. We show that, theoretically, for an optimal design enhancement factors of up to 60 are possible in the region of slow light. However, the overall transmission of bulk photonic crystals, and thus the performance of the device, is limited by fluctuations of the pore diameter. Numerical estimates suggest that the positional variations and pore diameter fluctuations have to be well below 0.5% to allow for a reasonable transmission of a 1 mm device.
Design of an Optical Gas Sensor Based on Silicon
The sensitivity of optical gas sensors depends on the length of interaction between detected radiation and the gas under investigation. A reduction in cell size of the sensor generally results in reduced sensitivity. Photonic crystals possess certain regions of their photonic band structure which offer low group velocities. Making use of these effects, smallervery compact -gas sensors should be possible. Problems to solve with numerical calculations are the identification of the operating point in relation to the photonic bandstructure and selection of an appropriate photonic crystal, the calculation of transmission through the photonic structure with and without the gas inside the sensor cell and the determination of an optimized anti-reflection-layer to improve the air-sensorinterface, since the low group velocity results in a high reflectivity.
Simulations of Sub-wavelength Metallo-dielectric Photonic Crystals for Gas Sensing
MRS Proceedings, 2006
ABSTRACTWe have simulated metallo-dielectric photonic crystals that are sharp thermal emitters at infrared wavelengths, and are being employed in gas sensors. The simulations were performed with a rigorous scattering matrix approach where Maxwell's equations are solved in Fourier space. These metallo-dielectric photonic crystals consist of a sub-wavelength hole array in a metal layer coupled to a two-dimensional photonic crystal of the same periodicity. The sub-wavelength hole array has an enhanced transmission mode that couples to a guided mode of the photonic crystal. The transmissive mode of the hole array is absorbed by the photonic crystal to create a sharp absorption and reflective minimum feature found for a range of lattice spacing. The structure thermally emits in a narrow band of wavelengths controlled by the lattice spacing that can be tuned over the infrared region. The underlying physics of this emissive device is modeled with rigorous scattering matrix simulations.
Optics Communications, 2015
We develop a versatile gas sensor based on the condition for total internal reflection at the glass-photonic crystal interface and corresponding detection scheme for rapid and precise measurement of vapors. The sensor consists of a vapor sensitive photonic crystal film as a Fabry-Perot etalon coated on a solid substrate (e.g., large face of a glass prism or glass slide). Such scheme and specific physicochemical properties of submicron silica particles provide photonic crystal sensor selectivity due to the capillary condensation of ammonia vapor with a sensitivity of 1 ppm with a response time of 100 ms.
Design of a compact photonic crystal sensor
Optical and Quantum Electronics, 2011
The development of technology in photonic crystal (PC) structures has seen rapid progress. Using PCs in biosensing area may open new venues to achieve single molecule detection, and high resolution scanning. A novel PC sensor with improved performances, in terms of size, compactness and sensitivity is presented in this paper. The sensing element consists of dielectric cylinders with varying radius introduced along <01> and <10> directions of the crystal. The results show that the peak wavelength shifts to the high frequency region when only six cylinders are filled with analytes. Also, the peaks show a larger shift compared to the structure obtained using the entire PC waveguide as sensing region. The proposed sensor shows a better sensitivity to water than other analytes, where the peak wavelength tends to shift towards the low frequency region.
Scientific Reports
Gas sensors are important in many fields such as environmental monitoring, agricultural production, public safety, and medical diagnostics. Herein, tamm plasmon resonance in a photonic bandgap is used to develop an optical gas sensor with high performance. the structure of the proposed sensor comprises a gas cavity sandwiched between a one-dimensional porous silicon photonic crystal and an Ag layer deposited on a prism. the optimised structure of the proposed sensor achieves ultra-high sensitivity (S = 1.9×10 5 nm/RiU) and a low detection limit (DL = 1.4×10 −7 RiU) compared to the existing gas sensor. the brilliant sensing performance and simple design of the proposed structure make our device highly suitable for use as a sensor in a variety of biomedical and industrial applications. Gas sensing has different applications in many fields such as the food industry, medicine, safety, environment, agriculture, and cosmetic 1,2. For example, the detection of volatile organic compounds such as acetone and toluene in exhaled breath is used as a biomarker for many diseases 3,4. In addition, the determination of the concentration of harmful gases such as CO 2 and N 2 O can be applied as an environmental pollution monitor 5. Currently, optical gas sensors are of great interest to researchers because they do not require complicated radioactive/fluorescent labels 6,7. Surface plasmon resonance, Tamm plasmon (TP) resonance, waveguide, and photonic crystal are all examples of platforms for optical sensing 8-12. Photonic crystals (PCs) are useful for a wide range of biomedical and environmental sensing applications. This is due to an impressive set of relevant properties, such as ultrahigh sensitivity, low detection limit, and fast response time 13,14. PC refers to a range of materials characterised by a periodic refractive index along one, two, or three dimensions (1DPC, 2DPC, or 3DPC, respectively). The propagation of electromagnetic waves in PCs can be controlled because of the photonic bandgap (PBG) 15-17. 1DPCs are more appropriate for most applications, given their low cost and ease of fabrication compared to 2DPCs and 3DPCs 18. Recently, PCs have been widely used in various sensor systems. A high-precision gas index sensor, which was proposed by Jágerská et al., reached a sensitivity of 510 nm/RIU based on a PC air-slot cavity 19. Hua-Jun studied a surface plasmon resonance nanocavity antenna array for use as a gas sensor with a high sensitivity of 3200 nm/RIU 20. Wang et al. suggested a guided-mode resonance gas sensor with a sensitivity as high as 748 nm/ RIU 21. Pevec and Donlagic designed a fiber-optic Fabry-Perot gas sensor with a sensitivity of 1550 nm/RIU 22. García-Rupérez et al. presented a highly sensitive device for antibody detection using the slow light regime of a PC waveguide 23. Chen et al. designed a PC/Ag/graphene structure to function as a refractive index sensor based on the Tamm state, with a numerical sensitivity of 1178.6 nm/RIU 24. Auguié et al. studied TP resonance at the interface between a metal/mesoporous PC. The numerical results showed that the sensitivity was approximately 55 nm/RIU 25. Recently, 1DPCs based on multilayers of porous silicon (PSi) have become an effective solution for the design of novel biosensors 26-28. PSi characteristically provides high surface area and low mass within small volumes. The optical properties of PSi can be controlled by changing the size of the pores and/or material that fills the pores 27. Moreover, PSi is compatible with integrated electronic circuits. In contrast, TP resonance is used as an optical sensor technology with high performance. TPs can be created inside the bandgap by adding a metal layer in front of the 1DPC 25. The wavelength location of the TP resonant dip
Wireless enabled multi gas sensor system based on photonic crystals
2010
In this paper we introduce a multi gas sensor system based on refractive index changes in a 2D slab photonic crystal. The sensor is formed by a L3 resonant cavity sandwiched between two W1.06 waveguides in the photonic crystal. The sensor configuration is similar to an Add-Drop filter structure. The transmission spectrums of the sensor with different ambient refractive indices ranging from n = 1.0 to n = 1.1 are calculated. The simulation results show that a change in ambient RI of Δn = 0.0008 is apparent with a corresponding change in output wavelength of the sensor of 2.4 nm. The properties of the sensor are simulated using the 3D finite-difference time-domain (FDTD) method. The Q-factor of the sensor is also optimized, with highest values reaching over 30,000. The sensor system is hybrid integrated with a wireless RF chip which processes the sensor data and transmits them in effect turning the entire system into a wireless sensor mote.