Research in atomic physics is at times somewhat equipment intensive: lasers, power supplies, photoreceivers, optical cavities, . . . As a result, getting a lab started with a limited budget can be intimidating. Fortunately, many of the tools we use every day are really quite simple at heart, so with a bit of time it is quite feasible to build many of them in-house. To this end, we have developed designs for a number of our day-to-day tools.
ECDLs
Nearly all of our diode lasers are home-built, grating stabilized Littrow-configurations based around the well known design of Arnold et al. described in Rev. Sci. Instrum. 69, 1 (1998). We have tweaked the design slightly and also incorporated a steering correction mirror along the lines of Hawthorn et al. in Rev. Sci. Instrum. 72, 4477 (2001). At this point we have built nearly ten of these lasers, using them throughout our lab and also in teaching laboratories. In our experience when properly assembled they have excellent long-term stability.
Our design is built from gently-modified stock components plus a few simple custom aluminum parts.
Solidworks files: ECDL_Assembly.zip
To drive our lasers we use home-built electronics based around the excellent current source from Dallin Durfee’s group at BYU, a temperature control module from Wavelength Electronics, and our own PZT driver. The PZT driver is sourced with +/- 15V and produces very low noise outputs of up to 90V at a bandwidth of up to 400 kHz. Further details are available in a paper which has been published in Rev. Sci. Instrum.
Board design files and detailed schematics are available: PZT_Driver.zip
Photodiode Circuit
We use photodiodes with a home-built variable-gain transimpedance amplifier for a variety of tasks around the lab. These designs are not particularly remarkable in terms of bandwidth or low-noise operation, but they are quite useful and fit into a convenient package similar in size to the popular NewFocus 20×1 and 205x series photoreceivers. Our design features 5-position transimpedance gain and 1x or 3x voltage gain to make it flexible for use with a wide variety of laser powers. Detector bandwidth is ~1 MHz, while 5-position low- and high- pass Chebyshev filters aid in rejection of out-of-band noise sources.
Board files, detailed schematics, and Solidworks drawings of our enclosure are available: Photodiode_Amp.zip
Mechanical Shutter Controller
Turning a laser on and off is a routine exercise in atomic physics laboratories. Fast control is typical implemented with an acousto-optic or electro-optic modulator, often permitting on/off times of under 100 nsec. However, scattering and effects mean that the extinction of such devices is rarely quite as good as desired for some experiments, thus “slow” mechanical shutters remain useful in experiments. One common design for these shutters is based off of the read/write arm of a hard drive (see Rev. Sci. Instrum. 75, 3077 (2004); Rev. Sci. Instrum. 78, 026101 (2007)). Following these papers we have implemented a four-channel shutter controller which we use to actuate shutters built from retired laptop hard drives.
Board files and schematics are available: Shutter_Controller.zip
Transfer Cavity Laser Stabilization
Our lab stabilizes most of our ECDLs by locking them to a commercial stabilized HeNe by monitoring frequency drift with a scanning Fabry-Perot cavity. This technique, which is well described in the literature (see for example Rev. Sci. Instrum. 62, 1656 (1991), Rev. Sci. Instrum. 69, 3737 (1998), and also John Barry’s thesis from the DeMille group at Yale), is quite general, and a good option when there are not convenient atomic transitions available to serve as frequency references.
While I was a postdoc I prepared an informal writeup which describes a fairly inexpensive set of optics and electronics that worked well for laser wavelengths from 400-900 nm. Though never intended to be widely disseminated – it was never edited beyond first-draft form, and features some tortured prose and typographical errors – it spent some time on the web and was surprisingly well read, especially by undergraduates. At this point it could use both editing and updating, but in service to the undergraduate AMO community I thought I would re-post it here. If you are considering building a similar setup drop me a line for suggestions.
