Grating-stabilized Diode Laser Research Articles

Crystal growth, low-temperature spectroscopy and multi-watt laser operation of Yb:Ca3NbGa3Si2O14

We report on the crystal growth, structure, room- and low-temperature (6K) absorption and emission spectroscopy of a 3at% Yb3+-doped trigonal ordered langasite-type silicate crystal, Ca3NbGa3Si2O14 (Yb: CNGS). The Rietveld refinement data are presented. Absorption, stimulated-emission and gain cross-sections are determined for the Yb3+ ion in CNGS for π and σ polarizations. The maximum stimulated emission cross-section amounts to σSE = 0.97 × 10−20cm−2 at 1014nm (σ-polarization). The Stark splitting of the Yb3+ multiplets is resolved. Microchip laser operation is obtained with both a-cut and c-cut 3at% Yb: CNGS samples under end-pumping at 976nm by a Volume Bragg Grating-stabilized diode laser. For the latter cut, the maximum output power reaches 7.61W at 1048–1060nm with a slope efficiency of 59%. By varying the output coupling, multi-watt emission over a 50nm-broad spectral range is achieved.

Measuring the linewidth of a stabilized diode laser

We demonstrate a straightforward technique to measure the linewidth of a grating-stabilized diode laser system-known as an external cavity diode laser (ECDL)-by beating the output of two independent ECDLs in a Michelson interferometer, and then taking the Fourier transform of the beat signal. The measured linewidth is the sum of the linewidths of the two laser systems. Assuming that the two are equal, we find that the linewidth of each ECDL measured over a time period of 2 μs is about 0.3 MHz. This narrow linewidth shows the advantage of using such systems for high-resolution spectroscopy and other experiments in atomic physics.

Narrow-bandwidth diode-laser-based blue and ultraviolet light source

A compact, tunable and narrow-bandwidth laser source for blue and ultraviolet radiation is presented. A grating-stabilized diode laser at 922 nm is frequency-stabilized to below 100 Hz relative to a reference resonator. Injection of the diode-laser light into a tapered amplifier yields a power of 0.5 W. In a first frequency-doubling stage, more than 200 mW of blue light at 461 nm is generated by use of a periodically poled KTP crystal. Subsequent second-harmonic generation employing a BBO crystal leads to about 1 mW of ultraviolet light at 231 nm.

Measurement of fast frequency fluctuations: Allan variance of a grating-stabilized diode laser

Fast frequency fluctuations of a 780 nm grating-stabilized diode laser are directly observed by the measurement of the Allan variance. Time intervals as short as 10 ns and up to 1 s are realized by means of two independent time interval counters. Frequency fluctuations with the laser locked to a Doppler-free resonance transition of atomic rubidium are examined in detail.

Inexpensive diode laser microwave modulation for atom trapping

We describe a simple modification to a grating-stabilized diode laser intended for use in neutral atom cooling and trapping. Modulation of the laser diode’s driving current at microwave frequencies induces sidebands in the laser’s spectrum that eliminate the need for a second laser in a trapping apparatus, yielding a considerable savings in effort and cost. A detailed description of the process for selection and assembly of microwave components is given. In an appendix we list the hardware used, with vendor and pricing information.

A compact grating-stabilized diode laser system for atomic physics

We describe a compact, economic and versatile diode laser system based on commercial laser diodes, optically stabilized by means of feedback from a diffraction grating. We offer detailed information which should enable the reader to copy our set-up which uses only easily machined mechanical parts. Our system offers single-mode operation with a linewidth of a few 100 kHz, continuous scans over 25 GHz, high chirp rates (up to 9 GHz/ms) and FM-modulation up to the GHz range. We discuss radio-frequency phase-locking of two independent lasers systems, allowing well controlled fast frequency switching which overcomes the limitations imposed by acousto-optic modulators.