High sensitivity infrared spectroscopy with a diamond waveguide on aluminium nitride
| Autor: | Pontus Forsberg, Mikael Karlsson, Patrik Hollman |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
Fabrication
Materials science business.industry Aluminium nitride Infrared spectroscopy Polishing Diamond engineering.material Cladding (fiber optics) Biochemistry Analytical Chemistry law.invention chemistry.chemical_compound chemistry law Analytisk kemi Electrochemistry engineering Environmental Chemistry Optoelectronics Quantum cascade laser business Waveguide Spectroscopy |
| Zdroj: | The Analyst. 146(22) |
| ISSN: | 1364-5528 |
| Popis: | Mid-infrared waveguide spectroscopy promises highly sensitive detection and characterization of organic molecules. Different material combinations for waveguides and cladding have been demonstrated with promising results, each with its own strengths and weaknesses in terms of sensitivity, transmission window and robustness. In this article we present a 5 μm thick diamond planar waveguide on aluminium nitride cladding, using a new fabrication and polishing method. Diamond has a very wide transmission window in the infrared, and its hardness and high chemical stability allows for chemistries and cleaning protocols that may damage other materials. With an aluminium nitride cladding the waveguide has a useable range between 1000 and 1900 cm−1, which we demonstrate using a tunable quantum cascade laser (QCL). This is a large improvement over silicon dioxide cladding. Compared to previously demonstrated free-standing diamond waveguides, the robustness of the sensor is greatly improved, which allows for a thinner diamond layer and increased sensitivity. The new waveguide was used in a QCL-based optical setup to detect acetone in deuterium oxide and isopropyl alcohol in water. The measurements showed higher sensitivity and lower noise level than previous demonstrations of mid-infrared diamond waveguides, resulting in a two orders of magnitude lower detectable concentration. |
| Databáze: | OpenAIRE |
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