Broadband sum-frequency generation using d_33 in periodically poled LiNbO_3 thin film in the telecommunications band

Abstract

We demonstrate the first, to the best of our knowledge, type-0 broadband sum-frequency generation (SFG) based on single-crystal periodically poled LiNbO₃ (PPLN) thin film. The broad bandwidth property was largely tuned from mid-infrared region to the telecommunications band by engineering the thickness of PPLN from bulk crystal to nanoscale. It provides SFG a solution with both broadband and high efficiency by using the highest nonlinear coefficient d₃₃ instead of d₃₁ in type-I broadband SFG or second-harmonic generation. The measured 3 dB upconversion bandwidth is about 15.5 nm for a 4 cm long single crystal at 1530 nm wavelength. It can find applications in chip-scale spectroscopy, quantum information processing, LiNbO₃-thin-film-based microresonator and optical nonreciprocity devices, etc.

Second-harmonic generation in nanophotonic PPLN waveguides with ultrahigh efficiencies

“…A narrower waveguide leads to a longer QPM wavelength due to modal dispersion, as is expected from numerical simulations. The measured for the 1440-and the 1380-nm-wide devices are 2600%/W-cm 2 and 2300%/W-cm 2 , respectively, over an order of magnitude higher than the best values reported in previous PPLN waveguides [9][10][11][12][13][14][15][24][25][26].…”

“…1(c)]. While an odd multiple of this period could be used for higher-order QPM, it significantly reduces the nonlinear interaction strength [14]. In this work we focus on first-order periodic poling, which requires precise control over the poling uniformity and yield on a micron scale throughout the chip.…”

Status and Potential of Lithium Niobate on Insulator (LNOI) for Photonic Integrated Circuits

“…In LNOI waveguides, QPM can be achieved by inverting the spontaneous polarization of the lithium niobate crystal periodically along the waveguide. The inversion of the crystal direction, also called domain inversion, can either be done before the lithium niobate thin‐film is bonded on the silica buffer layer in the LNOI wafer fabricated process or afterwards on the LNOI wafer itself . A method to generate domain patterns on LNOI is the electric field poling technique.…”

Ultrahigh-efficiency wavelength conversion in nanophotonic periodically poled lithium niobate waveguides

“…In recent years, thin-film LN wavelength-conversion devices have been pursued to achieve integrated devices with better light confinement and potentially much higher conversion efficiencies [16][17][18][19][20][21][22][23][24][25][26][27]. In this platform, the device layer consists of a singlecrystal, sub-micrometer-thick LN film, which is bonded on top of a low-index substrate (e.g., SiO 2 ) [28].…”