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[en] We present theoretical predictions and experimental results of a mid-infrared optical parametric oscillator (OPO) based on periodically poled lithium niobate. An air-space intracavity etalon causes our OPO to oscillate on a single longitudinal mode. Continuous frequency tuning of this mode is achieved by simultaneous adjustment of the etalon mirror spacing and the OPO resonator length with piezoelectric translators. We achieved 10 cm-1 of continuous frequency tuning and more than 10 cm-1 of mode-hop tuning. The OPO is pumped with 200 μJ/pulse by a seeded, 1-kHz, Q-switched Nd:YAG laser and provides as much as 10 μJ of energy in both the idler near the 3-μm wavelength and in the signal near the 1.6-μm wavelength. We obtained a resolution of 0.01 cm-1 with the idler when measuring the spectrum of the Q branch of the methane C-H stretch under Doppler-limited conditions. (c) 2000 Optical Society of America

[en] We present the experimental realization of a theoretical effect discovered by Olivares and Paris (2009 Phys. Rev. A 80 032329), in which a pair of entangled optical beams undergoing independent losses can see nonlocal correlations restored by the use of a nonlocal resource correlating the losses. Twin optical beams created in an entangled, Einstein-Podolsky-Rosen (EPR) state by an optical parametric oscillator above threshold were subjected to 50% loss from beamsplitters in their paths. The resulting severe degradation of the amplitude-quadrature correlations between the two beams was then suppressed when another, independent EPR state impinged upon the other input ports of the beamsplitters, effectively entangling the losses inflicted to the initial EPR state. The additional EPR beam pair was classically coherent with the primary one but had no quantum correlations with it. This result may find applications as a 'quantum tap' for entanglement.

[en] We investigate time-modulated EPR entangled states and intensity quantum correlation of twin light beams in application to time-resolved quantum communication. As a proper device generating such states, the nondegenerate optical parametric oscillator driven by the time-modulated pump field is considered.

[en] A frequency stabilizing system for a pulsed injection seeded 1550nm optical parametric oscillator (OPO) at 20 Hz repetition rate is demonstrated. The optical heterodyne method is used to measure the frequency difference between the seed laser and the OPO output. Using the frequency difference as the error signal, a proportionalintegral controller in combination with a scanner is applied to stably match the OPO cavity length to the seed laser frequency. The root-mean-square (rms) error of the frequency discrimination method is <0.07MHz according to a ‘frequency shifting-chopping-beat’ evaluation. The frequency fluctuation of the frequency-stabilized OPO is 0.29MHz (rms), and the Allan deviation is less than 20 kHz for averaging time of more than 3 s. (paper)

[en] The dynamics of dipolariton states in a planar microcavity has been studied upon pumping of a state corresponding to the middle dipolariton branch. It has been shown that, under exact resonance conditions, both periodic and aperiodic regimes of conversion of pump dipolaritons to dipolaritons of idler and signal modes occur. The periodic regime of conversion of signal and idler dipolaritons without involving pump dipolaritons on the middle branch has also been analyzed.

[en] A high-energy, extended-cavity femtosecond BiBO optical parametric oscillator synchronously pumped by a 1.0-ps, 1030-nm Yb:YAG, thin-disk pump laser is presented. The oscillator operated near degeneracy in a noncollinear interaction geometry, producing signal wavelength tunability from 1.99 to 2.20 μm. The signal pulses have an average power exceeding 2 W, producing 455-fs pulses at 7.08 MHz with energies up to 350 nJ, showing increased potential for tunable sources of scalable ultrafast pulses in the infrared.

[en] We present a solution to the minimum time control problem for a classical harmonic oscillator to reach a target energy E_T from a given initial state (q_i, p_i) by controlling its frequency ω, ω_min ≤ ω ≤ ω_max. A brief synopsis of optimal control theory is included and the solution for the harmonic oscillator problem is used to illustrate the theory.

[en] Tunable high-power THz-wave radiation is achieved via a compact eudipleural THz-wave parametric oscillator. The maximum THz-wave output is 1.164 V at 1.755 THz when the pump energy is 90 mJ. In the experiments we find that the maximum output of THz-wave moves to the high frequency band as the pump energy increases and this phenomenon is reasonably explained. The polarization characteristics of the THz-wave are analyzed. (authors)

[en] A parametric oscillator with damping driven by white noise is studied. The mean square displacement (MSD) in the long-time limit is derived analytically for the case that the static force vanishes, which was not treated in the past work (Tashiro and Morita 2007 Physica A 377 401). The formula is asymptotic but is applicable to a general periodic function. On the basis of this formula, some periodic functions reducing MSD remarkably are proposed