METHOD FOR WRITING SHORT PERIOD REFLECTION BRAGG DIFFRACTION GRATING USING PHASE MASK

PROBLEM TO BE SOLVED: To write Bragg diffraction gratings into an optical fiber. SOLUTION: This method includes a process for manufacturing the Bragg reflection diffraction gratings using a phase mask and an amplitude mask device for manufacture of a Bragg reflector. The Bragg reflection diffraction gratings have the periods larger than the periods of the conventional short period diffraction gratings but much smaller than the periods of the conventional long-period diffraction gratings. This short-period Bragg reflection diffraction gratings have periods in a range of, for example, 1 to 10 μm. The method of manufacture includes the arrangement of the amplitude mask having internally formed suitable slits on a photosensitive waveguide to be manufactured, then irradiation of the waveguide through the slits and the consequent introduction of the periodic patterns of refractive index fluctuations which are the characteristic of the Bragg reflector by light. The short-period Bragg diffraction gratings generated by this amplitude mask are the reflection diffraction gratings having the reflection characteristics attaining nearly 99.99%. The reflective diffraction gratings manufactured according to this method are advantageous in applications, such as adding and decreasing of channels into a wavelength division multiplex system and the detection of the stabilization and structural imperfectness of a laser.