Semrock VersaChrome Tunable Bandpass Filters

Thin-film filters that are tunable over a wide range of wavelengths by adjusting the angle of incidence with...

Semrock VersaChrome Tunable Bandpass Filters

By Semrock


The first widely tunable thin-film optical filters. Turan Erdogan, Ph.D. and Ligang Wang


Thin-film filters are the ideal solution for wavelength selection in most optical systems due to exceptionally high transmission (close to 100%), very steep spectral edges, and blocking of optical density 6 or higher over wide spectral regions for maximum noise suppression. However, until now thin-film filters have been considered “fixed” filters only, such that changing the spectral characteristics requires swapping filters. There are mechanical means to perform filter swapping, like filter wheels, but these are generally large in size, relatively slow (minimum switching times are typically 50 to 100 ms), and they permit only a limited number of filters (typically wheels contain from 4 to 12 slots). Thus, size, speed, and filtering flexibility are all limited. When higher-speed, more flexible wavelength changing is required, diffraction gratings ...

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