997 nm extended cavity diode laser for cesium spectroscopy and uniform electric field generation.

摘要

In this paper, I present two separate topics: laser preparation for use in cesium atomic spectroscopy and design of electric field plate configurations for the generation of uniform electric field. The laser, whose free running wavelength is 1005 nm, was assembled to produce a narrow-band output (less than 1 MHz FWHM), a high intensity (∼1W/cm2), and a wide mode-hop free tunable range (∼5 GHz). The ECDL (External Cavity Diode Laser) configuration with a diffraction grating was exploited, which enhances the laser output power and the laser quality while enabling one to tune the laser by means of rotation of the grating. The temperature/injection current controller unit was used and examples of the current tuning and temperature tuning are reported. The piezoelectric transducer (PZT) circuit was also used in parallel to tune the laser in a finer scale. Using this laser, with proper polarization set-up, a number of cesium spectroscopy results of the Cs 6P to 7P state transitions were collected. The motivation behind this cesium spectroscopy is to measure the relative strengths of electric-dipole-forbidden transitions, which would enhance our knowledge in the states accessible by single-photon or multi-photon processes. In addition, a simple method of measuring laser noise to estimate the linewidth of the laser is presented and confirms that the laser linewidth was indeed less than 1 MHz FWHM. In a separate project, I present the design of the electric field capacitor plate configuration inside a MOT chamber. The capacitor plates are separated by a distance comparable to their dimensions. In order to maintain uniform electric field between the plates, a few nodes with bias voltage were introduced at points between the plates to keep the electric potential gradient relatively constant. The numerical simulations in COMSOL showed that the uniformity of the electric field in the region between the plates was within less than 10% marginal error.