Working principle of 48AT-0

The collimated laser beam is constricted by a precision ball transported by a scaled micrometer screw. The subsequent single-mode fiber coupling is used as a mode filter.

This mechanically stable attenuation method allows the precise and reproducible setting of the laser power output over a wide range (typically 1.5 to > 60 dB). Unlike a power regulation by modulation of the laser current, the wavelength and polarization status of the laser beam are preserved.

A reproducible power attenuation is only assured for singlemode fibers that have a Gaussian intensity profile. In case of a multimode fiber not only the power is attenuated but also the intensity distribution ex fiber is affected. 

Attenuation and relative power output depending on the micrometer position of the precision ball.