Quantum theory of two-photon correlated-spontaneous-emission lasers: Exact atom-field interaction Hamiltonian approach

Journal Article · Wed Nov 15 04:00:00 EST 1989 · Physical Review (Section) A: General Physics; (USA)

DOI:https://doi.org/10.1103/PhysRevA.40.5735· OSTI ID:5289715

Lu, N; Zhu, S ^[1]

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1. Center for Advanced Studies and Department of Physics and Astronomy, University of New Mexico, Albuquerque, New Mexico 87131 (US)

A quantum theory of two-photon correlated-spontaneous-emission lasers (CEL's) is developed, starting from the exact atom-field interaction Hamiltonian for cascade three-level atoms interacting with a single-mode radiation field. We consider the situation where the active atoms are prepared initially in a coherent superposition of three atomic levels and derive a master equation for the field-density operator by using a quantum theory for coherently pumped lasers. The master equation is transformed into a Fokker-Planck equation for the antinormal-ordering {ital Q} function. The drift coefficients of the Fokker-Planck equation enable us to study the steady-state operation of the two-photon CEL's analytically. We have studied both resonant two-photon CEL for which there is no threshold, and off-resonant two-photon CEL for which there exists a threshold. In both cases the initial atomic coherences provide phase locking, and squeezing in the phase quadrature of the field is found. The off-resonant two-photon CEL can build up from a vacuum when its linear gain is larger than the cavity loss (even without population inversion). Maximum squeezing is found in the no-population-inversion region with the laser intensities far below saturation in both cases, which are more than 90% for the resonant two-photon CEL and nearly 50% for the off-resonant one. Approximate steady-state {ital Q} functions are obtained for the resonant two-photon CEL and, in certain circumstances, for the off-resonant one.

• OSTI ID: 5289715
• Journal Information: Physical Review (Section) A: General Physics; (USA), Journal Name: Physical Review (Section) A: General Physics; (USA) Vol. 40:10; ISSN PLRAA; ISSN 0556-2791
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
426002* -- Engineering-- Lasers & Masers-- (1990-)
ATOMS
CORRELATIONS
DIFFERENTIAL EQUATIONS
ELECTROMAGNETIC FIELDS
EMISSION
EQUATIONS
FEASIBILITY STUDIES
FOKKER-PLANCK EQUATION
HAMILTONIANS
LASERS
MATHEMATICAL OPERATORS
NONLINEAR OPTICS
OPTICAL PUMPING
OPTICS
PARTIAL DIFFERENTIAL EQUATIONS
PHOTON EMISSION
PUMPING
QUANTUM OPERATORS