https://doi.org/10.1007/s100530050258
Squeezed two-mode lasers without and with inversion
Department of Physics, Huazhong Normal University,
Wuhan 430079, P.R. China
Received:
22
December
1997
Revised:
25
March
1998
Accepted:
9
September
1998
Published online: 15 February 1999
On the basis of the nondegenerate 
quantum-beat laser model, we
introduce a coherent field which drives the transition between the upper
lasing level and an auxiliary level. We demonstrate that such a four-level
system can produce squeezed two-mode laser without and with inversion. When
the laser is operated well above threshold, the intensity fluctuation in the
average mode is reduced below the shot noise with an optimum Mandel
parameter 
. At the same time, the noises in the relative
amplitude and the relative phase drop to their vaccum noise levels.
Furthermore, regardless of inversion, noninversion, and transition between
inversion and noninversion, the optimum Mandel Q parameter of
is retained when the system operates well above threshold. A simple physical
explanation of the squeezing mechanism for two-mode squeezing is given.
PACS: 42.50.Lc – Quantum fluctuations, quantum noise, and quantum jumps / 42.50.Ar – Photon statistics and coherence theory / 42.50.Dv – Nonclassical field states; squeezed, antibunched, and sub-Poissonian states; operational definitions of the phase of the field; phase measurements
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999
