Curved grating spectrometer and wavelength multiplexer or demultiplexer with very high wavelength resolution

摘要

The present application discloses a system comprising a compact curved grating (CCG) and its associated compact curved grating spectrometer (CCGS) or compact curved grating wavelength multiplexer/demultiplexer (WMDM) module and a method for making the same. The system is capable of achieving a very small (resolution vs. size) RS factor. In the invention, the location of the entrance slit and detector can be adjusted in order to have the best performance for a particular design goal. The initial groove spacing is calculated using a prescribed formula dependent on operation wavelength. The location of the grooves is calculated based on two conditions. The first one being that the path-difference between adjacent grooves should be an integral multiple of the wavelength in the medium to achieve aberration-free grating focusing at the detector or output slit (or output waveguide) even with large beam diffraction angle from the entrance slit or input slit (or input waveguide). The second one being specific for a particular design goal of a curved-grating spectrometer. In an embodiment, elliptical mirrors each with focal points at the slit and detector are used for each groove to obtain aberration-free curved mirrors.

主权项

1. A wavelength multiplexer/demultiplexer suitable for analyzing a spectra composition of an optical beam, the wavelength multiplexer/demultiplexer enabling a detection of light of a particular wavelength, the wavelength multiplexer/demultiplexer comprising:
an input slit for allowing an entry of the optical beam into a spectrometer, a location of the input slit, being adjustable, and further the location of the input slit specified by a first angle with respect to a normal of a rating center of a curved grating and a first distance from the grating center; a first output slit for allowing the exiting of a first exit optical beam having a first wavelength, a location of the first output slit being adjustable, and further the location of the first output slit specified by a second angle with respect to the normal of the grating center of the curved gratin and a second distance from the grating center; anda second output slit for allowing the exit of a second exit optical beam having a second wavelength, a location of the second output slit being adjustable, and further the location of the second output slit specified by a third angle with respect to the normal of the grating center of the curved grating and a third distance from the grating center,
wherein the second distance and third distance are nearly equal so that both slits are near a circle with radius Rout centered at the grating center.