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A simple and highly reliable laser system for cold atom experiments

A simple and highly reliable laser system for cold atom experiments

Optics Communications 290 110-114 (2013)
D. Sahagun, V. Bolpasi, and W. von Klitzing
http://dx.doi.org/10.1016/j.optcom.2012.10.013 (local link)
Abstract:
The increasing complexity of cold atom experiments puts ever higher demands on the stability and reliability of its components. We present a laser system for atom cooling experiments, which is extremely reliable yet simple to construct and low-cost, thus forming an ideal basis for ultracold atom experiments such as Bose-Einstein condensation and degenerate Fermi gases. The extended cavity (master) diode and slave lasers remain locked over a period of months with a drift in absolute frequency well below 1MHz with a line-width of less than 300kHz. We generate the repumper light by modulating the current of an injection locked slave laser at a frequency of 6.6GHz. The construction of the laser is simple and largely based on off-the-shelf electronic and optomechanical components.

Design

The basic idea of this laser system is to keep the individual elements modular, so that a fault in one part of the system can be repaired by only changing the sub-system with zero changes elsewhere.  Each parts in the graph on the right thus represents a separate bread-board.

The article also describes a very simple diode laser with extraordinary long term stability (depicted here on the right). This master-laser uses simply to machine parts and a commercial mirror mount for holding the grating.  The diode holder and mirror mount are screwed onto an aluminium base plate, which is glued onto a Peltier element, which in turn is glued onto a base.  The whole assembly is then surrounded by thick-walled aluminium box, which has been lined with standard isolation foam.