Apodized holographic beam combiners for dense wavelength multiplexing based on Gaussian-beam interference

The brightness of high-power diode-laser systems can be significantly increased by using dense wavelengthmultiplexing technologies. Among these technologies, state-of-the-art volume holographic gratings (VHGs) are suitable wavelength-selective filters for scaling the power of frequency-stabilized high-power lasers. The frequency spacing is limited due to the sidelobes of the spectral filter characteristic. In this Letter, we present the simulation results of novel apodized VHGs produced by Gaussian-beam interference. Apodized VHGs offer increased sidelobe suppression of up to 22 dB with conventional grating dimensions and, moreover, will improve the spectral brightness of dense wavelength-multiplexing systems by a factor of approximately six.