Santec TSL-210 - 13-3 Built-in Attenuator

TUNABLE LD LIGHT SOURCE TSL-210
13-3
13-3 Built-in Attenuator
13-3-A Introduction
By adopting an external cavity structure the product has maintained various semiconductor
laser features. In particular this structure make it possible to tune the wavelength of the laser
light. However, the optical output power is controlled by tuning the LD injection current.
This causes a change in the optical path length in the LD that can consequently cause an opti-
cal wavelength shift or cause difculty in maintaining adequate SSR (side-mode suppression
ratio). To counter these problems, a tunable attenuator (ATT) can be tted on the output side of
the external cavity. This is available as an option. The data below shows a comparison of the
spectrum of the output signal with the output power set to -15dB with and without the attenua-
tor.
13-3-B Features and Principle Structure
An optional feature is the ability to reduce the optical output power loss from installing a vari-
able attenuator in the optical test set-up. By including an internal ATT, variable attenuation
is realized with a minimum of optical power loss when compared with an external attenuator
set-up. An attenuator is made of a mechanically tunable graded ND lter. It can be tuned con-
tinuously with the resolution of 0.1dB within 0 to 20dB attenuation range.
Without ATT With ATT
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