Enhanced mid-infrared gas absorption spectroscopic detection using chalcogenide or porous germanium waveguides

Abstract

Different integrated photonic sensors are investigated for the detection in the mid-infrared region of the two gases namely CO2 and CH4. The three studied structures are ridge waveguides, based both on chalcogenide films (ChG) or porous germanium (PGe) and slot waveguides based on ChG. Waveguide dimensions are optimized to obtain the highest power factor between guided light and gas while maintaining a single mode propagation in the mid-infrared wavelength range. The achievable power factor is 1% in case of ChG ridge-waveguide, 45% for PGe-ridge, and 58% in case of ChG-slot. Extremely low limits of detection (LOD), 0.1 ppm for CO2 at λ = 4.3 μm and 1.66 ppm for CH4 at λ = 7.7 μm are obtained for a ChG slot waveguide, due to the large gas absorption coefficients in the mid-infrared spectral range. For PGe waveguides, low LOD values are also computed: 0.12 ppm for CO2 at λ = 4.3 μm and 1.89 ppm for CH4 at λ = 7.7 μm. These results show that the proposed structures could achieve competitive performance required for generic spectroscopic detection on a chip for environment and health sensing.

Large‐Scale Formation of Uniform Porous Ge Nanostructures with Tunable Physical Properties

“…Porous semiconductor materials have received an increasing interest for both fundamental research and advanced applications owing to their unique mechanical and physicochemical properties compared to their bulk material counterparts. [ 1–4 ] Porous germanium (PGe) in particular shows a potential in wide range of implementations such as energy storage systems, [ 5–10 ] thermoelectric devices, [ 11 ] sensors, [ 12–14 ] optoelectronics, [ 15,16 ] or synthesis of nanocomposite materials. [ 17–19 ] Moreover, PGe has recently been demonstrated as an efficient virtual substrate for epitaxial growth of detachable Ge membranes [ 20 ] and III‐V heterostructures with high crystalline quality [ 21,22 ] paving the way to direct application in the development of lightweight and flexible photovoltaics and optoelectronics.…”

Theoretical Demonstration of the Interest of Using Porous Germanium to Fabricate Multilayer Vertical Optical Structures for the Detection of SF6 Gas in the Mid-Infrared

“…Porous materials are attractive materials for many different sensing applications because of their large internal surface area [ 8 , 9 ], open pores network [ 10 ], and widely tunable refractive index [ 11 ]. Several structures using porous materials, especially porous silicon (PSi), have been demonstrated, such as omnidirectional mirrors [ 12 ], multilayers [ 13 ], microcavities [ 14 ], and waveguides [ 15 ]. The potential application areas of porous materials are mainly in the fields of biotechnology [ 16 ], microelectronics [ 17 ], and energy conversion [ 18 ].…”

“…Compared to silicon (Si), whose transparency window ranges from 1 to 8 μm, porous Ge (PGe) benefits from the larger transparency window of Ge extending from 2 to 15 μm. Furthermore, the strong light–matter interaction, conferred by its pores network, has attracted a growing interest for its use in various integrated detection applications [ 15 , 24 ].…”

Compact and Highly Sensitive Bended Microwave Liquid Sensor Based on a Metamaterial Complementary Split-Ring Resonator

“…Wireless sensor networks are essential in our society, and are becoming an integral part of our environment [1][2][3][4][5][6]. These sensors are the object of very active research because of the growing interest in them in many areas, such as environmental monitoring [1,2], industrial control [3], information security [4], the Internet of vehicles [5] and network lifetime [6]. The goal of these studies is to develop sensitive, fast, and easy-to-use sensors.…”