Alpes Lasers ECLK, User Manual

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1. Description
1.1 Introduction
Alpes Laser’s line of External Cavity Laser Kit (ECLK) is designed for single-mode op-
eration with wide spectral tunability. The ECLK consists of a quantum cascade laser
(QCL) gain chip, a grating-tuned extended optical cavity in Littrow configuration, laser
drive electronics, an Alpes Lasers TC-3 temperature controller, and a graphical user
interface software. The kit is delivered pre-aligned and ready to use. Additional gain
chips with different wavelength coverage and/or output power can be purchased from
Alpes Lasers and installed in the instrument by the user. In the case of purchasing a
gain medium only, initial alignment and calibration steps are necessary. Characteri-
zation data are supplied with every kit and gain medium.
The ECLK is compatible with the Alpes Lasers line of Broad Gain QCLs which tune
over up to
30% of their center wavelength. The gain medium is prepared in form of
antireflection (AR) coated Fabry-Perot cavity, soldered to an aluminium nitride sub-
mount and to a copper carrier. The temperature is actively regulated by a heatsink
assembly that includes a thermoelectric element and water cooling for improved heat
dissipation. The laser is driven by an Alpes Lasers S-2 pulsed driver. The graphical
user interface allows for automatic wavelength tuning.
The back facet beam is collimated with an ashperical collimator lens onto a diffraction
grating mounted on a motorized rotation stage. The first order diffracted beam is fed
back into the gain chip. The laser frequency is tuned by rotating the grating. The front
facet (output) beam is collimated by another asperical collimator and is collected at
the front side of the kit after passing through a one-inch-diameter AR coated output
window.
For improved performance, the kit can be operated in a purged atmosphere. The
electrical connectors and plugs for water cooling and gas purging are found at the
back panel of the ECLK.
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