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Connection between degenerate parametric oscillation and two-photon correlated-spontaneous emission laser

Shi-Yao Zhu, L. Z. Wang, Chang Su

Published May 21, 1990• 0 citations
OpenAlex

Abstract

There are many similarities between the degenerate parametric oscillation1,2 (DPC)) and two-photon correlated-spontaneous emission laser3,4 (CEL). Both have the capability of producing a squeezed state. In particular, a maximum 50% intracavity squeezing can be obtained at threshold, and the squeezing will decrease above threshold for both cases. These similarities motivated us to investigate the connection between them.

Related papers

Similarity and difference between degenerate parametric oscillators and two-photon correlated-spontaneous-emission lasers

Shi-Yao Zhu, Marlan O. Scully

The degenerate parametric oscillator (DPO) is analyzed with the nonlinear material treated quantum mechanically. The source of squeezing in the DPO is the same as in the two-photon correlated-spontaneous-emission laser (CEL)--the level coherence. In this sense, they are similar. The amount of squeezing in DPO is the same as in the two-photon CEL at two-photon resonance, but the gain in DPO is usually much smaller than that in the two-photon CEL at two-photon resonance.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Sep 1, 1991•0 citations

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

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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 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 Q functions are obtained for the resonant two-photon CEL and, in certain circumstances, for the off-resonant one.

Physical Review A•Nov 1, 1989•38 citations

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Journal of the Optical Society of America B•May 1, 1991•0 citations

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A quantum theory of a two-mode two-photon correlated spontaneous-emission laser is developed. It is shown that the quantum-noise quenching and even nonclassical effects can occur in both the average phase and relative amplitude of the two fields. Near threshold we find a maximum of 50% intracavity squeezing in the two-photon transition limit, with each of the average phase and the relative amplitude contributing 25% squeezing.

Physical Review A•Mar 1, 1990•24 citations

Phase and photon-number squeezings in a many-cascade two-photon correlated-spontaneous-emission laser

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I show that, in the case of both one- and two-photon resonances, a many-cascade two-photon correlated-spontaneous-emission laser can generate light exhibiting phase and photon-number squeezings. Optimizing the mean photon number in the cavity with respect to a phase factor sin[1/2(n-1)\ensuremath{\theta}]/sin(1/2\ensuremath{\theta}), we find that the maximized mean photon number and its squeezing increase with increasing the top populations ${\mathrm{\ensuremath{\rho}}}_{\mathit{n}\mathit{n}}^{\mathit{a}}$ of the active atoms. However, the photon-number squeezing may decrease, increase, or not change when increasing the number n-1 of lower, almost degenerate atomic levels, depending on the relative phase \ensuremath{\theta} of lower atomic states determined by the optimization conditions. The phase squeezing has a maximum value with increasing n-1 and ${\mathrm{\ensuremath{\rho}}}_{\mathit{n}\mathit{n}}^{\mathit{a}}$.

Physical Review A•May 1, 1994•0 citations

Two-photon correlated–spontaneous-emission laser: Quantum noise quenching and squeezing

Marlan O. Scully, K. Wódkiewicz, Muhammad Suhail Zubairy +3 more

Previous studies have shown that the possible utility of the two-photon laser as a squeezed-state generator is negated by spontaneous-emission fluctuations. We here show that a two-photon correlated--spontaneous-emission laser can produce light which is both squeezed and free from spontaneous-emission fluctuations.

Physical Review Letters•May 2, 1988•202 citations
There are many similarities between the degenerate parametric oscillation1,2 (DPC)) and two-photon correlated-spontaneous emission laser3,4 (CEL). Both have the capability of producing a squeezed state. In particular, a maximum 50% intracavity squeezing can be obtained at threshold, and the squeezing will decrease above threshold for both cases. These similarities motivated us to investigate the connection between them.
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 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 Q functions are obtained for the resonant two-photon CEL and, in certain circumstances, for the off-resonant one.
I show that, in the case of both one- and two-photon resonances, a many-cascade two-photon correlated-spontaneous-emission laser can generate light exhibiting phase and photon-number squeezings. Optimizing the mean photon number in the cavity with respect to a phase factor sin[1/2(n-1)\ensuremath{\theta}]/sin(1/2\ensuremath{\theta}), we find that the maximized mean photon number and its squeezing increase with increasing the top populations ${\mathrm{\ensuremath{\rho}}}_{\mathit{n}\mathit{n}}^{\mathit{a}}$ of the active atoms. However, the photon-number squeezing may decrease, increase, or not change when increasing the number n-1 of lower, almost degenerate atomic levels, depending on the relative phase \ensuremath{\theta} of lower atomic states determined by the optimization conditions. The phase squeezing has a maximum value with increasing n-1 and ${\mathrm{\ensuremath{\rho}}}_{\mathit{n}\mathit{n}}^{\mathit{a}}$.