Generation of 116-mW output power at 461 nm in a periodically poled lithium niobate waveguide

We demonstrate a second harmonic generation (SHG) of 116 mW at 461 nm in a periodically poled lithium niobate waveguide when the power of the 922-nm fundamental light is coupled into the waveguide was 350 mW. The waveguide is 12.5 μm wide, 12.0 μm thick, 22 mm long, and has a 1-mm-long slab window at the output facet of the waveguide. The temperature acceptance bandwidth of the phase-matching curve of the SHG is approximately 0.5 °C. The SHG system demonstrates good beam quality and is reliable for cold atom experiments, including research on optical lattice clocks.

PR37 An Alternative Strategy for Photon-Pair Generation using Integrated Photonics on Silicon Wafers (1640968-Y4)

Research activities include the design, fabrication and poling of a spontaneous parametric down-conversion (SPDC) waveguide in periodically-poled thin-film lithium niobate SPDC device, and measurements of photon-pair generation in it. Summary of a Project Outcomes report of research funded by the U.S. National Science Foundation under Project Number 1640968 (Year 4).

A systematic study of PPLN length dependence in intracavity SHG

In this paper, a systematic study of the relationship between nonlinear crystal length and intracavity second-harmonic generation (SHG) using MgO-doped periodically-poled lithium niobate (MgO:PPLN) is presented. The experimental results demonstrate a relationship between the maximum SHG power generated and the full-width at half maximum (FWHM) of the crystal’s temperature tuning curve to the length of the nonlinear optical crystal. It was shown that maximum SHG power increases rapidly with the increase of MgO:PPLN length, reaching a saturation length (~ 2 mm), which is much shorter than that predicted by the single-pass SHG theory. This saturation length of the MgO:PPLN crystal is almost independent on 808 nm pump power for typical powers used in continuous wave intracavity SHG lasers. In addition to this saturation effect, a broadening effect was also observed, the FWHM of the temperature tuning curve was shown to have a larger FWHM than that predicted by the single-pass SHG theory for MgO:PPLN shorter than the saturation length. This work has the benefit of allowing engineers to optimize nonlinear crystal length when developing intracavity SHG based diode-pumped solid state (DPSS) lasers.

Phase-sensitive amplification based on gradient Er:PPLN

The present research focuses on the study of the phase-sensitive amplification based on periodically poled lithium niobate (PPLN) made from gradient Er doped lithium niobate. It is shown that the presence of a growing Er gradient increases the gain while maintaining phase sensitivity to the input signal.

Optical Frequency Down-Conversion With Bandwidth Compression Based on Counter-Propagating Phase Matching

Optical quantum network plays an important role in large scale quantum communication. However, different components for photon generation, transmission, storage and manipulation in network usually cannot interact directly due to the wavelength and bandwidth differences, and thus interfaces are needed to overcome such problems. We propose an optical interface for frequency down-conversion and bandwidth compression based on the counter-propagating quasi-phase-matching difference frequency generation process in the periodically-poled lithium niobate on insulator waveguide. We prove that a separable spectral transfer function can be obtained only by choosing proper pump bandwidth, thus relaxing the limitation of material, dispersion, and working wavelength as a result of the counter-propagation phase-matching configuration. With numerical simulations, we show that our design results in a nearly separable transfer function with the Schmidt number very close to 1. With proper pump bandwidth, an photon at central wavelength of 550 nm with a bandwidth ranging from 50 GHz to 5 THz can be converted to a photon at central wavelength of 1,545 nm with a much narrower bandwidth of 33 GHz.

Estimation of second harmonic generation intensity-noise in random periodically poled lithium niobate

Periodically poled lithium niobate (PPLN) predominantly has a random duty-cycle error (RDE), latent in them by virtue of poling mechanism. This error needs to be quantitatively predicted to abstain from parasitic harmonic generation. In this paper, we have calculated the influence of the RDEs degenerate noise in second-harmonic generation (SHG) consisting of PPLN. Here, we propose a method for calculating the random domain-wall distribution statistics by the SHG. We explored the equivalence between the statistics of random domain distribution by SHG and far-field diffraction pattern method.