Ultrafast variable attenuators

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Newport Corporation has introduced the first set in a series of ultrafast variable attenuators (UVAs). Compact, robust, and easy-to-use, the ultrafast attenuators are available in manual (UVA-800-M) and motorised (UVA-800-Conex) versions. The new attenuators are designed to address the challenge of safely attenuating the output of ultrafast amplifiers.

The UVAs are composed of specially designed thin film polarisers, zero-order achromatic waveplates, and high-precision opto-mechanics, enclosed in shuttered housings. Specially designed high-damage threshold, thin-film polarisers are pre-aligned in the sealed housing to minimise exposure to dust and other contaminants. The thin-film polarisers are utilised in conjunction with a half-waveplate providing continuously adjustable intensity ratio splitting of the dual S- and P-polarised outputs.

The P-polarised output passes through the first polariser with negligible beam deviation and minimal dispersion. The S-polarised output is reflected off two polarisers in a parallel offset (1-inch) from the fundamental, with negligible dispersion. Both outputs have high polarisation contrast ratios (greater than 1:450) and require no adjustment over the entire working range. For added functionality, the sealed housing includes a manual shutter for the S-polarised port and a removable beam dump on the P-polarised port.

The motorised version's rotational stage has an integrated Conex controller/driver, which is powered and communicates via a USB port. A free Nstruct applet to control the stage is available for download from Newport’s website.