Production of degenerate polarization entangled photon pairs in the telecom-band from a pump enhanced parametric downconversion process.

The design and implementation of a novel source of degenerate polarization entangled photon pairs in the telecom band, based on a cavity enhanced parametric downconversion process, is presented. Two of the four maximally entangled Bell states are produced; the remaining two are obtainable by the addition of a half wave plate into the setup. The coincident photon detection rate in the A/D basis between two detectors at the output of the device revealed the production of highly entangled states, resulting in quantum interference visibilities of 0.971 ± 0.041 (ϕ = 0 state) and 0.932 ± 0.036 (ϕ = π state) respectively. The entangled states were found to break the Clauser-Horne-Shimony-Holt (CHSH) Bell inequality by around 6 standard deviations. From the measured coincidence counting rates and the optical system losses, an entangled photon pair production rate of 8.9 × 10(4) s(-1) mW(-1) pump was estimated.

Stable, continuous-wave, intracavity, optical parametric oscillator pumped by a semiconductor disk laser (VECSEL).

We report relaxation oscillation free, true continuous-wave operation of a singly-resonant, intracavity optical parametric oscillator (OPO) based upon periodically-poled, MgO-doped LiNbO3 and pumped internal to the cavity of a compact, optically-excited semiconductor disk laser (or VECSEL). The very short upper-laser-state lifetime of this laser gain medium, coupled with the enhancing effect of the high-finesse pump laser cavity in which the OPO is located, enables a low threshold, high efficiency intracavity device to be operated free of relaxation oscillations in continuous-wave mode. By optimizing for low-power operation, parametric threshold was achieved at a diode-laser power of only 1.4 W. At 8.5 W of diode-laser power, 205 mW of idler power was extracted, indicating a total down-converted power of 1.25 W, and hence a down-conversion efficiency of 83%.

Compact, continuous-wave, singly resonant optical parametric oscillator based on periodically poled RbTiOAsO4 in a Nd:YVO4 laser.

We describe a compact all-solid-state continuous-wave, singly resonant optical parametric oscillator (SRO) based on periodically poled RbTiOAsO4. The SRO is pumped at 1.064 microm by a Nd:YVO4 laser, which is itself pumped by a 3-W diode laser. Using the intracavity technique produced an oscillation threshold for the SRO of only 1.6 W (diode-laser power). For 3 W of diode pump power some 65 mW was obtained in the (nonresonant) idler (wavelength 3.52 microm). Temperature tuning over the range 10-100 degrees C resulted in tuning ranges of 1.52-1.54 and 3.41-3.54 microm for the signal and the idler waves, respectively. Importantly, relaxation oscillations were absent.