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Integrated waveguide with a microfluidic channel in spiral geometry for spectroscopic applications

“…[12][13][14][15] Light from the waveguide core penetrates the surrounding liquid where specific analyte is homogeneously distributed. The penetration depth d p is a function of the waveguide core and liquid index, and can be estimated for a given wavelength as follows: 12,13 …”

Low-loss PbO2 diffusion waveguide used as a sensitive gas sensor

“…The detection of dangerous and harmful gases represents an important issue in ecology, chemistry, environmental monitoring, and defense. [1][2][3] The control of atmospheric ammonia levels is especially important because it is a flammable and explosive gas. Apart from its natural origin, it has many sources.…”

“…We previously described an opto-chemical sensor scheme featuring a resonance amplifier and lock-in detector with mechanical recording of the output signal. 1,3 However, the measurement setup had the following drawbacks: a time response exceeding one second, the production of analog signals, and a high sensitivity to mechanical noise. Laser power losses were also very high in the optical waveguides, to the point of affecting the metrological characteristics of the sensor.…”

“…Using this expression, we calculated N min NH 3 ≈ 0.1 ppm for a signal-to-noise ratio of about 20. (1) and output (2) prisms, the integrated optical waveguide (3), and the TE 0 -mode track (4). When ammonia is delivered to the sensor cell, the ouput laser power decreases.…”

An integrated optical gas sensor with improved sensitivity and time response

“…Different types of sensors have been designed based on various physical and chemical properties. [1][2][3][4] Environmental monitoring and physical ecology, in particular, require the development of sensors that can determine parameters such as temperature, pressure, humidity, composition of mixtures, and gas concentration. Progress in this area is closely related to advances in opto-chemical sensor technology.…”