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.

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.

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.

A Broadband High-Diffraction-Efficiency Electro-Optic Bragg Deflector Based on Monolithic Dual-Grating Periodically-Poled Lithium Niobate

Electro-optic (EO) Bragg deflectors have been extensively used in a variety of applications. Recent developments show that bandwidths and deflection efficiencies, as well as angular bandwidths, would significantly limit the utilization of EO Bragg deflectors, especially for applications which need strong focusing, such as intra-cavity applications. In this paper, we introduce a broadband EO Bragg deflector based on periodically-poled lithium niobate with a monolithic dual-grating design. We analyzed the deflection properties of this device by using a modified coupled wave theory and showed that this device can be still efficient for a small beam radius under strong focusing, whereas a single-grating one becomes very inefficient. Using a 1064-nm laser beam with a 100-μm beam radius, we obtained a 74% deflection efficiency with a 190-V bias voltage with a 0.5-mm-thick and 7.5-mm-long dual-grating sample. The acceptance angle for the Bragg condition of this device is as large as a few tens of mrad. The potential bandwidth of this device exceeds 500 nm if the proper operation region is chosen.

Photon Conversion and Interaction on Chip

The conversion and interaction between quantum signals at a single-photon level are essential for scalable quantum photonic information technology. Using a fully-optimized, periodically-poled lithium niobate microring, we demonstrate ultra-efficient sum-frequency generation on chip. The external quantum efficiency reaches (65±3)% with only (104±4) uW pump power, improving the state-of-the-art by over one order of magnitude. At the peak conversion, 3×10-5 noise photon is created during the cavity lifetime, which meets the requirement of quantum applications using single-photon pulses. Using pump and signal in single-photon coherent states, we directly measure the conversion probability produced by a single pump photon to be 10-5---breaking the record by 100 times---and the photon-photon coupling strength to be 9.1 MHz. Our results mark a new milestone toward quantum nonlinear optics at the ultimate single photon limit, creating new background in highly integrated photonics and quantum optical computing.

A compact and high efficiency intracavity OPO based on periodically poled lithium niobate

We demonstrate a compact, high efficiency and widely tunable intracavity singly resonant optical parametric oscillator (IC-OPO) based on multichannel periodically poled lithium niobate (PPLN). The IC-OPO is composed of 808 nm pump laser diode (LD), Nd:YVO4 laser and linear OPO. The continuous-wave (CW) mid-infrared (MIR) output laser is tunable from 2.25 to 4.79 μm. The maximum output power exceeds 1.08 W at 3.189 μm at 9.1 W LD pump power and the conversion efficiency is 11.88%. We also build up a prototype with volume of 145 × 85 × 42.5 mm3 and its total weight is less than 2 kg. The measured power stability is 1.3% Root Meat Square (RMS) for a 3 h duration under simulated high temperature conditions of 40 °C. RMS is 2.6% for a 4 h duration when simulated temperature is − 40 °C.