Diagram of the (a) main laser body, (b) diode collimation-tube mount, and (c) optical isolator mount (“aspirin tablet” size). Not pictured are the lids and baseplate. All pieces are machined from 6061-T6 aluminum.
Laser assembly: cutaway top view (with all peripherals but no electrical connections) and front view (with lids and baseplate).
Assembled laser: close-in view of the main cavity of the laser with the top lid removed.
Assembled laser mounted on table: A composite block and viscoelastic cushioning material isolate the laser from table vibrations, and a flexible, molded silicone cover offers further acoustic isolation and temperature regulation.
Older “bronze” diode laser in use in our lab: We compare this model to the new design in all stability measurements.
Cavity resonance spectroscopy: rms error signal as a function of the driving frequency of the laser's piezo. Included are plots of the new design both with (solid red line) and without (dashed green line) shear damping as well as our lab's original bronze Littrow laser model (dotted blue line). In the inset, the same data are plotted on a logarithmic vertical scale.
Frequency-noise spectral density for the old bronze design (green), new stable design (red), and detector background (blue). Inset are the same data on a logarithmic scale from 100 Hz to 10 kHz.
Spectral response exhibited by the old bronze design (green) and the new stable design (red) for an air-horn perturbation (105 dBA local sound intensity). In the inset, the same data are plotted on a logarithmic vertical scale.
Measured self-heterodyne spectra (solid green lines) and fits (dashed blue lines) to the model described in the text, for four different fiber-optic delay lengths, for the 922 nm laser. Averaged over the four fits, the fitted spectral parameters are γ/2π = 1.86(29) kHz and kHz.
Heterodyne signal (solid green line) and fit (dashed blue line) between two identical 780 nm lasers, acquired using a 20-kHz Gaussian resolution bandwidth. The fitted spectral parameters are γ/2π = 20(10) kHz and kHz.
Summary of the lasers characterized by the self-heterodyne technique. R d is the diode front-facet reflectivity, R g is the measured diffraction grating efficiency, and L c is the external cavity length. Also included are measured linewidth parameters (white-noise and 1/f components) and calculated FWHM for T obs = 100 μs. The diode and diffraction grating combination used for each wavelength are, respectively: old 780 nm—Sharp Microelectronics GH0781JA2C and Edmund NT43-751; new 780 nm—Sharp Microelectronics GH0781JA2C and Richardson 53-*-330H; 922 nm—Sacher SAL-920-60 and Richardson 53-*-239H; and 689 nm—Sacher SAL-690-25 and Richardson 53-*-059H.
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