Photodetector and beating spectroscopy device
AssigneeHamamatsu Photonics K.K.
InventorsTatsuo Dougakiuchi, Akio Ito, Masahiro Hitaka, Tadataka Edamura, Naota Akikusa
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Abstract
A beating spectroscopy device includes: first and second quantum cascade lasers; a quantum cascade detector; and a sample holder configured to hold a sample on an optical path between the second quantum cascade laser and the quantum cascade detector. Lights from the first and second quantum cascade lasers are detected by the quantum cascade detector while a wavelength of the light from the second quantum cascade laser is changed to scan a frequency of a beating signal having a frequency in accordance with a wavelength difference between the lights from the first and second quantum cascade lasers.
Claims15
A beating spectroscopy device comprising:
- a first quantum cascade laser that is a fixed wavelength light source;
- a second quantum cascade laser that is a variable wavelength light source;
- a quantum cascade detector that detects first light traveling along a first optical path from the first quantum cascade laser to the quantum cascade detector and second light traveling along a second optical path from the second quantum cascade laser to the quantum cascade detector, wherein the quantum cascade detector includes a light receiving surface formed by a cleavage surface of a stripe-shaped mesa portion;
- a sample holder configured to hold a sample on the second optical path, wherein the sample holder causes the second optical path to be longer than the first optical path;
- an optical combiner that combines the first light and the second light;
- and
- a first lens disposed on the second optical path between the sample holder and the optical combiner to reduce a beam divergence of the second light that is increased due to the second optical path being longer than the first optical path;
- and
- a second lens disposed between the optical combiner and the quantum cascade detector to converge the first light and the second light onto the light receiving surface,
- wherein the first light and the second light are detected by the quantum cascade detector while a wavelength of the second light is changed to scan a frequency of a beating signal having a frequency in accordance with a wavelength difference between the first light and the second light, and
- wherein a converging lens is not disposed on the first optical path between the first quantum cascade laser and the optical combiner.
Dependencies are inferred from the claim text.