Contribution to the theory of single-mode laser modulation

L. Aubrecht

R. N. Shakhmuratov, A. R. Kessel

P. Titterton

A rigorous quantum-mechanical treatment of the internally phase-modulated laser is performed in terms of traveling-wave modes of the quantized electromagnetic field. A detailed treatment of the modulation process is consistent not only with the phase-locked and FM behavior of the laser, but also describes the external (to the laser cavity) frequency shifting of phase-locked light and single-frequency ("super-mode") operation of the FM laser.

A. Cassimi, Bernard Cheron, J. Hamel

$^4$He (2 $^3$S$_1$) metastable atoms are optically pumped with intensity modulated light. The use of a single mode diode-pumped LNA laser as the pumping source, allows the study of resonance signals predicted by the optical pumping theory but not yet observed. Resonances are detected on the transmitted pumping beam at the modulation frequency and its harmonics. Application of this method to high sensitivity magnetometers is suggested.

Kōichi Shimoda

Sin Hyuk Yim, D. Cho

We produced a pair of coherent laser beams with a 3-GHz frequency difference by optically phase locking two modes from a single, multimode extended-cavity diode laser. This method is complementary to either a direct modulation or an optical phase locking of two independent lasers. A large differential frequency shift between the two modes of the laser allows efficient phase locking. We developed a simple theory to account for the large differential frequency shift. Allan deviation of the beat frequency when the two modes are phase-locked drops as an inverse of the measurement time and it reaches 10(-14) when the time is 1 h. Coherent population trapping spectroscopy of Rb atoms using the phase-locked beams resulted in a spectrum as narrow as that of the case using direct modulation by a stable frequency synthesizer.