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We demonstrated a high-brightness, polarization-entangled bi-photon source generated in a type-II phase-matched non-collinear PPKTP crystal pumped by a 405 nm continuous-wave (cw) broadband diode laser. Basing on the single-pass configuration, we investigated the distribution characteristics of the bi-photon cone and the wavelength tunability with crystal temperatures. Overcoming the degradation of the bi-photon generation rate and the spectral correlation induced by the broadband pump laser, we obtained a bi-photon generation rate of 7. 48 × 10 3/s/mW/nm and an interference visibility over 95% via a Hong–Ou–Mandel (HOM) configuration. We established a theoretical model to address the bi-photon time-delayed HOM dip pumped by the broadband cw diode laser in spontaneous parametric down-conversion and obtained the complete analytic solution of the bi-photon coincidence counting rates. • The manuscript presented a detailed experimental and theoretical study of the fundamental properties of bi-photon pairs source generated in a non-collinear type-II PPKTP crystal. • Based on a Hong–Ou–Mandel (HOM) interference configuration, a high-flux bi-photon generation rate of 7.48 × 103/s/mW/nm and a high interference visibility over 95% are obtained by using of a broadband diode laser. • A reasonable theoretical model is established to address the bi-photon time-delayed HOM-dip pumped by the broadband cw diode laser via the spontaneous parametric down-conversion (SPDC). The complete analytic solution of the coincidence counting rate of bi-photons is obtained. [ABSTRACT FROM AUTHOR]

We present the strict design parameters of the experiment for the 780 nm tunable continuous-wave second harmonic (SH) generation by the nonlinear resonator containing a MgO doped periodically poled LiNbO (MgO:PPLN) crystal. Optimization of such critical parameters, including focusing and impedance matching, more than 84% SH conversion efficiency and 3.1 W available output power at 780 nm were obtained from the fundamental wave at 1560 nm with two different input couplers. The thermal saturated behavior of the SH output power has been observed in the experiment. The beam quality factor M of the generated SH wave is 1.04 (1.03), and the RMS power stability is 1.29% in 3 h. The SH wave was further used to detect the D transitions of Rb atom, exhibiting a fine tunable characteristic. Such laser source can be a suitable candidate in the atomic physics and quantum optics. [ABSTRACT FROM AUTHOR]

We experimentally present a three-mirror folded singly resonant sum-frequency generation (SFG) cavity with an adjustable input coupling, which has been applied to 520-nm single-frequency laser generation via 780-nm laser and 1560-nm laser frequency mixing in a periodically poled KTiOPO4crystal (PPKTP). A continuous variation in the input coupling reflectivity from 81.4 to 96.1% for 780-nm resonant laser is achieved by tilting the input coupler, and the impedance matching of the resonator can be optimized. Up to 268 mW of SFG output power at 520-nm is obtained with 6.8 W of the 1560-nm laser input and 1.5 W of 780-nm laser input. [ABSTRACT FROM AUTHOR]

We demonstrated a continuous-wave (CW) 780 nm laser with Watt-level output power by using external-cavity-enhanced frequency doubling of an Erbium-doped fiber amplifier (EDFA) boosted 1560 nm diode laser in a periodically-poled magnesium-oxide-doped lithium niobate (PPMgO:LN) bulk crystal. A 780 nm laser with maximum output power of 1.5 W is obtained at an incident 1560 nm laser of 2.05 W, corresponding to a doubling efficiency of 73%. The typical fluctuation of 780 nm laser׳s power is 1.2% (rms) in about 30 min. This 780 nm laser can be potentially applied to laser cooling and manipulation of rubidium atoms, generating 1560 nm squeezed vacuum field as well as 1560 nm continuous-variable entanglement based on optical parametric oscillator if additional locking and noise suppression is applied. [ABSTRACT FROM AUTHOR]

Abstract: The asymmetrical phase-matching temperature tuning curves of periodically-poled 5%-mol MgO-doped lithium niobate (MgO:PPLN) bulk crystals for frequency doubling of 1560nm telecom laser have been observed experimentally and analyzed theoretically. We find that the asymmetrical phenomena are resulted from the variation in the extraordinary refractive index by the doping concentration inhomogeneity of the crystals. The critical parameters of phase-matching temperature mismatching γ(γ=δT pm /ΔT, in which δT pm is the change of the phase-matching temperature due to the doping concentration inhomogeneity, and ΔT is the temperature acceptance bandwidth) and the thermal refractive index are investigated. Our analysis method is not only a reasonable explanation to the experiment, but also can be a simple evaluation way of optical quality of the given MgO:PPLN bulk crystals. Moreover, the MgO:PPLN bulk crystal is used in single-pass configuration for frequency doubling a 4.4W Erbium-doped fiber amplifier boosted 1560nm telecom laser, and 300mW of tunable 780nm laser is obtained, corresponding to a conversion efficiency of 6.9%. This source provides a simple and compact laser system for rubidium atom cooling and manipulation experiments. [Copyright &y& Elsevier]

Magic wavelength optical-dipole trap (ODT) allows confinement of neutral atoms and cancellation of the position-dependent spatially inhomogeneous differential light shift for a desired atomic transition. The light shift of the 87Rb 5P3/2�state can be expediently tailored to be equal to that of the 87Rb 5S1/2�state by employing dicromatic (λ1�+�λ2�(here λ2�= 2λ1�∼ 1.5��m)) linearly polarized ODT lasers. In our calculation, two sets of state-insensitive dichromatic (784.3�+�1568.6�nm and 806.4�+�1612.8�nm) are obtained for the 87Rb 5S1/2�(F = 2) – 5P3/2�(F′ = 3) transition. Further, 784.3�+�1568.6�nm dicromatic laser system with a moderate output power has been realized experimentally by marrying efficient second-harmonic generation using a PPMgO:LN bulk crystal with a fibre-amplified 1.5��m telecom laser. [ABSTRACT FROM AUTHOR]

Recently, vector beams with special intensity and phase distribution have received much attention due to their unique properties. In this paper, we construct the double‐petal linear edge dislocation (DPLED) beams based on Gaussian vortex beams. The distribution of intensity, polarization, and spin angular momentum (SAM) of the DPLED beams is analyzed in tightly focused based on the Richards‐Wolf vector diffraction theory. The significant difference is occurred in light field, polarization SAM, and polarization distributions before and after focusing of DPLED beams. It's of certain importance for expanding the application of vector beams in optical control, optical imaging, and other fields. [ABSTRACT FROM AUTHOR]

We have demonstrated 1.61 W of 780 nm single-frequency continuous-wave laser output with a semi-monolithic periodically poled potassium titanyl phosphate (PPKTP) crystal doubler pumped by a 2-W erbium-doped fiber amplifier boosted 1560 nm diode laser. The measured maximum doubling efficiency is 77%, and the practical value should be 80% when taking into account the fundamental-wave mode matching efficiency. The measured beam quality factor of 780 nm output, M 2 , is better than 1.04. Typical root-mean-square fluctuation of 780 nm output is less than 0.5% in 30 minutes. This compact frequency doubler has good mechanical stability, and can be employed for many applications, such as laser cooling and trapping, atomic coherent control, atomic interferometer, and quantum frequency standard with rubidium atoms. [ABSTRACT FROM AUTHOR]