In applications in which single photons must be detected, such as in spectroscopy, confocal or STED microscopy, single molecule detection, and quantum cryptography, it is not only important to achieve an extremely low dark count rate of the detector, but a detection efficiency that is as high as possible. Depending on the version, the single photon counting modules from Laser Cpmponents exhibit efficiencies of > 80% at 670 nm and > 50% at 405 nm.

To realize a fiber coupling, additional optical elements are needed. In COUNT modules with FC connectors a special GRIN lens is integrated that images single photons from the fiber onto the detector chip. With the in-house IBS coater, LASER ­COMPONENTS optimize the lenses with a double-sided AR coating. This broadband coating from 400 nm - 1100 nm has a reflection of less than 1.5%, and has thus led to a reduction in losses in detection efficiency.

Because of the in-house production, we are able to customize the coatings. For example we can offer AR coatings with a reflection of <<1% in the range from 400 nm to 900 nm or from 600 nm to 1100 nm.

For COUNTblue modules with increased sensitivity in the blue to yellow spectral range, we designed a special AR coating option that has a reflection of less than 1% from 350 nm to 700 nm.

More information at www.lasercomponents.com/