Correlated Spontaneous Emission in a Zeeman Laser and High Resolution Optical Multiplex Spectroscopy

M. P. Winters, J. L. Hall

M. P. Winters, J. L. Hall

Motoichi Ohtsu, K.-Y. Liou

Recently, correlated spontaneous emission in a laser of three-level atoms has been analyzed theoretically and has been demonstrated experimentally using a three-level He-Ne Zeeman laser. We demonstrate that correlated spontaneous emission is also feasible in a semiconductor laser with a long extended cavity. As a result, the heterodyned spectral width between two lasing modes in a grating extended-cavity laser was reduced to below the spontaneous emission noise level. The laser can be used for high-precision optical-heterodyne sensing.

Stanislav O. Konorov, Xiaoji G. Xu, John W. Hepburn +1 more

High-peak-power ultrafast lasers are widely used in nonlinear spectroscopy, but often limit its spectral resolution because of the broad frequency bandwidth of ultrashort laser pulses. Improving the resolution by achieving spectrally narrow excitation of, or emission from, the resonant medium by means of multiphoton interferences has been the focus of many recent developments in ultrafast spectroscopy. We demonstrate an alternative approach in which high resolution is exercised by detecting narrow spectral correlations between broadband excitation and emission optical fields. All-optical correlation analysis, easily incorporated into a traditional spectroscopic setup, enables direct, robust, and simultaneous detection of multiple narrow resonances in a single measurement.

Shigeru Nakayama

A theoretical analysis of the relative intensities of the Doppler-free signals in saturation spectroscopy, velocity selective optical pumping (VSOP) spectroscopy, polarization spectroscopy and a mixing of saturation and polarization spectroscopies is presented using the approximation of a single cycle of optical pumping in a four-level system. An optical pumping process in the Zeeman sublevels is taken into account owing to the important role of spontaneous emission even if the sublevels are degenerate. Arbitrary polarization combinations are considered for pump and probe beams. The similarities and differences between three kinds of spectroscopy are made clear. Both circular and linear optical anisotropies induced by the pump beam are considered in this theoretical calculation. The magnitude and sign of Doppler-free resonances in each spectroscopy are quite different owing to the polarizations of the pump and probe beams. The four-level system is important as a three-level approximation. The results obtained from the four-level optical pumping theory are in good agreement with experimental reports.

M. Orszaga, J. Bergoub, Wolfgang P. Schleich