Write-in characteristics of multiple volume holographic gratings for wavelength demultiplexing with wide spectra

The Bragg matching and the uniformity of Bragg diffraction efficiencies of multiple volume holographic gratings (MVHGs), which were used for wavelength demultiplexing devices in optical communication based on all wave optical fiber, were theoretically studied and quantitatively analyzed. It was shown that the Bragg mismatching would be caused due to the recording medium dispersion during wavelength demultiplexing with wide spectra by employing MVHGs. Moreover the Bragg diffraction efficiencies of MVHGs with homogeneous refractive index modulation obtained at short writing wavelength would not be uniform at different optical communication wavelengths. And it has been experimentally demonstrated. For this reason, the improved dependence of writing angles on communication wavelengths for fabricating angle-multiplexing transmission MVHGs and the corrected formula for refractive index modulation of individual MVHG at writing wavelength were presented in order to ensure rigorous Bragg matching and the uniformity of diffraction efficiencies.