Characterization of commercially available vertical-cavity surface-emitting lasers tuned on Cs D1line at 894.6  nm for miniature atomic clocks.
We report on the metrological characterization of novel commercially available 894.6 nm vertical-cavity surface-emitting lasers (VCSELs), dedicated to Cs D1line spectroscopy experiments. The thermal behavior of the VCSELs is reported, highlighting the existence of a minimum threshold current and maximum output power in the 55°C-60°C range. The laser relative intensity noise, measured to be -108  dB/Hz at 10 Hz Fourier frequency f for a laser power of 25 μW, is reduced with increased power. The VCSELs frequency noise is 108Hz2/Hz at f=100  Hz. The spectral linewidth of the VCSELs is about 30 MHz. VCSELs injection current can be directly modulated at 4.596 GHz with microwave power in the range of -10 to +0  dBm to generate optical sidebands. A VCSEL was used in a microcell-based Cs atomic clock based on coherent population trapping. A preliminary clock short-term fractional frequency stability of 8×10-11τ-1/2up to about 100 s is reported, demonstrating the suitability of these VCSELs for miniature atomic clock applications.
Eric
E
Kroemer
Jaroslaw
J
Rutkowski
Vincent
V
Maurice
Rémy
R
Vicarini
Moustafa Abdel
MA
Hafiz
Christophe
C
Gorecki
Rodolphe
R
Boudot