Optical grating in optical lead mfr. esp. for dispersion compensator with waveguide gratings

摘要

The method provides an optical grating (1) in an optical conductor or lead (2), which extends along a predetermined longitudinal axis (21) of the lead (2). The grating has, along this axis (21), a refractive index (n) at least approximating a periodically oscillating target waveform (11), and/or a grating amplitude (delta n) following a target waveform (13) and/or a grating constant (G) following a target waveform (15). The grating is produced by allowing a refractive index changing means to act on the lead material. At least one optical signal is sent along the axis (21) of the resulting grating (10). Using this signal, a complex optical spectrum of the grating is measured at least approximately. A pulse response of the grating is calculated at least approximately from the measured spectrum using an inverse Fourier transformation. The actual values of the refractive index and/or the grating amplitude and/or the grating constant are calculated from the calculated pulse response by solving a one-dimensional stray problem. A difference between the actual values and the target values is derived. These differences are balanced out, at least partly, by allowing a refractive index changing means e.g. irradiation, heat treatment, application of voltage etc., to act on the lead material.