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Diode Laser Spectroscopy

Diode Laser Spectroscopy Brochure

Newsletter 1 – The Fabry-Perot Addition
Newsletter 2 – Coherent Population Trapping 'Quantum Fun'...
Learn about Fabry-Perot Cavity

Conceptual Introduction – Diode Laser Spectroscopy
Diode Laser Spectroscopy-Saturated Absorption and Crossover Transitions

Lab Topics :
Atomic Physics
Modern Physics
Quantum Optics

The Instrument

Diode Laser Spectroscopy

TeachSpin's Laser Diode Spectroscopy Lab is shown here configured for simultaneous saturated absorption spectroscopy and interferometric determination of the frequency sweep of the laser.
A block diagram is shown below.

The centerpiece of the apparatus is the grating stabilized 780 nm diode laser. Honed to research quality by our senior scientist, George Herold, the laser is both temperature and current regulated. Optical feedback from a grating retro-reflects laser light to create an external cavity that stabilizes the laser to run at a controllable wave length. A piezo stack, mounted in the grating support,allows the grating angle to be modulated by an applied voltage. Using the internal ramp generator to modulate both the laser current and the piezo stack, students readily achieve laser frequency sweeps of as much as 10 GHz.

The outstanding quality of this stabilized diode laser makes it useful in the research laboratory. To serve this need, the laser head and controller can be purchased separately. Individual photodiode detectors are also available. The detector unit consists of a photodiode with a low-noise preamplifier and comes with complete mounting hardware.

Reflecting TeachSpin's instructional philosophy the controller, shown below, is divided into modules which the student must interconnect. Each module can be interrogated independently, encouraging exploration of the effects of changing a wide variety of parameters. Within the modules, students turn dials to control the laser current, the laser temperature, the cell temperature, the piezo stack, and the ramp generator as well as the gain and summing of the detector signals. A separate power supply is used to control the magnetic field created by the high homogeneity Helmholtz coils.

Controller for TeachSpin's Diode Laser Spectroscopy Lab

Two Optical System Versions can be purchased and partial systems are also available.

Diode Laser Spectroscopy (DLS1-A), the full version of the apparatus, supplies all of the optics in the photograph and block diagram shown above. In addition to the Laser Head, Complete Electronics, and 3 Diode Lasers (tested), this system includes: 3 Photodiode Detectors with preamplifiers, IR Viewing Card, CCD Camera, TV Monitor, the Absorption Cell Assembly (Rb Cell, Helmholtz Coils, Cell Heater, Rotating Stand), 2 pairs of Safety Goggles, Special Tools, a Black Anodized Aluminum Optical Bread Board 24" x 48" and an Instructor/Student Manual written by Professor Kenneth Libbrecht of Caltech. The Optics, for which all mounts and bases are supplied, include 5 Mirrors, a High Power Neutral Density Filter, 2 Neutral Density Filter sets with a holder, 0.5 degree Optical Wedge, 1.0 degree Optical Wedge, 50/50 Beam Splitter, Fixed Beam Splitter, 2 Rotating Linear Polarizers, and 2 Rotating 1/4-Wave Plates.

Basic Experiments Only is a simplified version which does not include the optics needed for simultaneous interferometry or for the magnetic field experiments. Items deleted from the complete optics package are 1 Photodiode Detector, 3 Mirrors, the 1.0 degree Optical Wedge, the Fixed Beam Splitter, 2 Rotating Linear Polarizers and 2 Rotating 1/4-Wave Plates. For schools that purchase the basic system this set of deleted optics items will be available as an upgrade.

Either the complete or basic system can be purchased without the optical breadboard.

Partial Systems are also available which will be sufficient for use in the research lab.

Tunable Diode Laser and Controller includes the Laser Diode Head, 3 Diode lasers (tested), the electronic Controller (with cell temperature controller and detector electronics included, and 2 pair of Mandatory Savety Goggles.

Photodiode Detectors, as noted earlier, are also available individually.

The Absorption Cell Assembly can also be purchased individually and includes the Rubidium Cell, Cell Heater, Thermocouple, a Rotatable Cell Mount and the 10 mT Helmholtz Coils.

Learn about Fabry-Perot Cavity .