Characterisation of ultra-narrow band filters for diode laser systems based on dense wavelength division multiplexing

We present a measurement platform to characterise combining elements used for dense wavelength division multiplexing, such as dielectric edge filters or Volume Bragg Gratings (notch filters). This platform enables the characterisation of the spectral and angular selectivity, the homogeneity of reflectance or transmittance and temperature-induced spectral shift of the band edge. The determination of the diffraction efficiency, the reflectance and the transmittance is carried out for both polarisations with high accuracy.