Photon etc. inc.’s Tunable Top Notch Filters block a narrow bandwidth while maintaining up to 80% throughput between 350 nm and 2.5 μm. They provide access to Raman shifts as low as 10 cm–1, with a minimum of OD4 and a tuning range of several hundred nanometers. Based on volume Bragg gratings, the all-glass holographic filters are compact and easy to align. The computer-controlled systems are supplied with drivers and control software through a USB interface.