Abstract: A medical instrument is described that includes an optical source, an optical fiber, and a waveguide patterned upon a substrate. The optical fiber receives radiation from the optical source and includes a first segment and a second segment. The second segment is rotated about an optical axis relative to the first segment. The waveguide receives radiation from the optical source and guides a beam of radiation. The waveguide includes a first waveguide segment designed to impart a first differential group delay on the beam of radiation and a second waveguide segment designed to impart a second differential group delay on the beam of radiation. A sum of the first differential group delay and the second differential group delay is substantially zero.

Abstract: A photodetector element for infrared light radiation of a given wavelength, in a medium that is at least partially transparent to the infrared light radiation to be detected. The photodetector includes a layer of a partially absorbent semiconductor and a periodic structure placed at a distance from and in the near field of the semiconductor layer and exciting propagation modes parallel to the semiconductor layer, of the infrared light radiation to be detected. There is a perimetric electrical contact that frames the outline of the photodetector element and extends perpendicularly relative to the planes defined by the semiconductor layer and the periodic structure, which makes contact with said semiconductor layer, and that also forms an optical mirror for the modes excited by the periodic structure.