{"id":246,"date":"2010-05-10T13:20:31","date_gmt":"2010-05-10T18:20:31","guid":{"rendered":"http:\/\/people.williams.edu\/pmajumde\/diode-laser-locking\/"},"modified":"2010-05-11T10:15:20","modified_gmt":"2010-05-11T15:15:20","slug":"diode-laser-locking","status":"publish","type":"page","link":"https:\/\/sites.williams.edu\/pmajumde\/current-experiments-and-apparatus\/diode-laser-locking\/","title":{"rendered":"Diode laser locking"},"content":{"rendered":"

Simple Methods for stabilization of diode lasers.<\/span><\/h4>\n

We have developed two different methods for simple and convenient stabilization of diode laser systems that are used in our work — and have potentially broad applicability. \u00a0Both schemes use Doppler-broadened (vapor cell) atomic samples. \u00a0These techniques remove long-term drifts, producing residual noise below the 1 MHz level for time scales from 10 msec to 100 sec. \u00a0These methods are described in the following Review of Scientific Instruments articles:<\/p>\n

Low-field Faraday rotation locking scheme<\/span><\/a><\/p>\n

AOM-based multiple beam locking scheme<\/span><\/a><\/p>\n

Faraday Rotation scheme<\/span><\/strong><\/span><\/p>\n

\"\"<\/a><\/p>\n

This method is particularly useful for locking to the side of atomic transition (as we would require for our differential phase shift spectroscopy method). \u00a0We have a optical polarimeter capable of detecting microradian-level optical rotation changes (similar to the design used for atomic parity violation experiments at UW Seattle). \u00a0An atomic vapor cell (thallium in our case) is placed between the polarizer and analyzer of the system. \u00a0Applying an AC magnetic field to a Faraday glass allows sinusoidal polarization modulation, and lock-in detection is used to obtain high-precision optical rotation signals. \u00a0By applying very small (few Gauss) magnetic fields to the atomic sample, we can obtain very high signal-to-noise Faraday rotation lineshapes, at which point we feedback the polarimeter signal to the laser PZT to hold the output polarization fixed. <\/span><\/span><\/p>\n

Here is a layout of the setup<\/span><\/a><\/span><\/span><\/p>\n

Here is some data demonstrating locking effectiveness<\/span><\/a><\/span><\/span><\/p>\n

This scheme offers the ability to lock over a wide range of frequencies on either side of an atomic resonance. \u00a0In our application, we study a ‘forbidden’ M1\/E2 transition, demonstrating that this scheme is well-suited to non-E1 transitions, where saturated absorption schemes are not convenient.<\/span><\/span><\/p>\n

AOM-based multiple-beam locking scheme<\/strong><\/p>\n

\"\"<\/a><\/p>\n

Charles Cao ’09 with laser locking apparatus, including AOM, supplementary vapor cell oven, and signal processing electronics<\/em><\/p>\n

<\/a>We developed this scheme for our most recent indium work where, again, we require long-term frequency stability at the 1 MHz level, and appreciate the convenience of lock point tunable over nearly 1000 MHz. \u00a0Again, we use a Doppler-broadened heated cell (indium in this case. \u00a0Our blue laser produces efficient second-order diffraction in an AOM tuned to 200 MHz. \u00a0By double-passing, we obtain a large number of frequency-shifted beams, in particular, two shifted by 800 MHz (roughly one-half of the Doppler-broadened profile). \u00a0These beams, first intensity-matched, are sent together through a heated indium cell, and the laser is tuned near the desired hyperfine resonance of the 410 nm line. <\/a>Two frequency shifted absorption dips result.<\/a> We use the resulting differential transmission signal as an error signal, which is processed and fed back to the laser PZT.<\/span><\/span><\/p>\n

Here is the optical layout for this scheme (photo above shows the optical system and locking cell)<\/span><\/a><\/span><\/span><\/p>\n

Here is a sample of the locking effectiveness \u00a0of the scheme<\/span><\/a><\/span><\/span><\/p>\n

A further improvement to this scheme, offering better common mode noise rejection, is to polarization-tag and then analyze the two laser beam frequency components, so that they truly co-propagate through the cell. \u00a0This simple and robust method greatly facilitated our recent indium two-step spectroscopy experiment.<\/p>\n


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Simple Methods for stabilization of diode lasers. We have developed two different methods for simple and convenient stabilization of diode laser systems that are used in our work — and have potentially broad applicability. \u00a0Both schemes use Doppler-broadened (vapor cell) … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":93,"featured_media":0,"parent":143,"menu_order":3,"comment_status":"closed","ping_status":"closed","template":"","meta":{"_acf_changed":false,"footnotes":""},"class_list":["post-246","page","type-page","status-publish","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/sites.williams.edu\/pmajumde\/wp-json\/wp\/v2\/pages\/246","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sites.williams.edu\/pmajumde\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/sites.williams.edu\/pmajumde\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/sites.williams.edu\/pmajumde\/wp-json\/wp\/v2\/users\/93"}],"replies":[{"embeddable":true,"href":"https:\/\/sites.williams.edu\/pmajumde\/wp-json\/wp\/v2\/comments?post=246"}],"version-history":[{"count":16,"href":"https:\/\/sites.williams.edu\/pmajumde\/wp-json\/wp\/v2\/pages\/246\/revisions"}],"predecessor-version":[{"id":282,"href":"https:\/\/sites.williams.edu\/pmajumde\/wp-json\/wp\/v2\/pages\/246\/revisions\/282"}],"up":[{"embeddable":true,"href":"https:\/\/sites.williams.edu\/pmajumde\/wp-json\/wp\/v2\/pages\/143"}],"wp:attachment":[{"href":"https:\/\/sites.williams.edu\/pmajumde\/wp-json\/wp\/v2\/media?parent=246"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}