Generation of Spectral Clusters in a Mixture of Noble and Raman-Active Gases

Abstract: We report a novel scheme for the generation of dense clusters of Raman sidebands. The scheme uses a broadband-guiding hollow-core photonic crystal fiber (HC-PCF) filled with a mixture of H2, D2, and Xe for efficient interaction between the gas mixture and a green laser pump pulse (532 nm, 1 ns) of only 5 uJ energy. This results in the generation from noise of more than 135 ro-vibrational Raman sidebands covering the visible spectral region with an average spacing of only 2 THz. Such a spectrally dense and compact fiber-based source is ideal for applications where closely spaced narrow-band laser lines with high spectral power density are required, such as in spectroscopy and sensing. When the HC-PCF is filled with a H2-D2 mixture the Raman comb spans the spectral region from the deep UV (280 nm) to the near infrared (1000 nm).