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A Tunable External Cavity Diode Laser Using a Volume Holographic Reflection Grating PIs: Dana Z. Anderson (PI), Victor M. Bright (Co-PI)
Students: Ho-Chiao Chuang (Rick), Ricardo Jimenezmartinez, Simon Braun Project field/specialty: Atomic Physics, Optics, Micro-fabrication Project Description:
Laser diodes have been well documented for their suitability in the field of laser cooling and atom trapping. They are now widely used in many experiments in optical and atomic physics. Although these devices are compact, simple, and relatively inexpensive, unmodified laser diodes do have some undesirable properties, mostly as a result of their short semiconductor cavity. In particular, their frequency is very sensitive to changes in temperature and injection current, and they have large linewidths ~100 MHz and poor tunability. It is well known that these shortcomings can be rectified by operating the laser in a longer external cavity which provides frequency-selective optical feedback. A particularly simple implementation of this idea uses feedback from a diffraction grating mounted in the Littrow configuration in which it is very difficult to find a pivot position between the grating and diode. In G. Ewald's and A. Wicht's work, they have developed a diode laser setup by use of a volume holographic transmission grating. However, there is no temperature control for the diode and gratings. In this project, we describe a whole new method for constructing a smaller extended-cavity diode laser by use of a volume holographic grating. Its performance is similar to that of Sheng's design but it is particularly smaller, inexpensive and easy to build because it is based on simple modifications of a few commercial optical and mechanical components but with a specific silicon flexure design made by micro-fabrication technology for the laser frequency tuning.
The previous laser system design and Rubidium D2 line transition spectrums are shown in the following figures.
Funding Source: DARPA
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