Abstract: Practical diffractive optical elements are made available efficiently and at low-cost. A refractive-index-modulated diffractive optical element includes a transparent DLC (diamond-like carbon) film (2) formed on a transparent substrate (1), with the DLC film (2) containing a diffraction grating having local regions (2a) of a relatively high refractive index and local regions (2) of a relatively low refractive index. The DLC film (2) can readily be deposited by plasma CVD onto the substrate (1), and the high refractive-index regions (2a) within the DLC film can readily be formed by irradiating it with an energy beam (4) such as an ion beam.

Abstract: Affords efficiently and at low cost optical fibers capped at the end with a working, tiny optically diffractive film. An optical fiber (F) includes a diffractive film (DF) formed onto an endface thereof, or onto the endface of a collimator (C) joined to the endface of the fiber; the diffractive film includes a transparent DLC (diamond-like carbon) layer; and the DLC layer includes a modulated-refractive-index diffraction grating containing local regions of relatively high refractive index and local regions of relatively low refractive index.

Abstract: Affords efficiently and at low cost practical, tiny light-emitting devices having an optically diffractive film on their light-output face. A light-emitting device (LD) includes a diffractive film (DF) formed on its light-output face; the diffractive film includes a transparent DLC (diamond-like carbon) layer; and the DLC layer includes a modulated-refractive-index diffraction grating containing local regions of relatively high refractive index and local regions of relatively low refractive index.