分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Lithium niobate (LN) thin film has recently emerged as an important platform for nonlinear optical investigations for its large $\chi^{(2)}$ nonlinear coefficients and ability of light localization. In this paper, we report the first fabrication of LN on insulator (LNOI) ridge waveguides with generalized quasi-periodic poled superlattices using the electric field polarization technique and microfabrication techniques. Benefiting from the abundant reciprocal vectors, we observed efficient second-harmonic and cascaded third-harmonic signals in the same device, with the normalized conversion efficiency 1735% W$^{-1}$cm$^{-2}$ and 0.41% W$^{-2}$cm$^{-4}$, respectively. This work opens a new direction of nonlinear integrated photonics based on LN thin film.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Lithium niobate on insulator (LNOI), regarded as an important candidate platform for optical integration due to its excellent nonlinear, electro-optic and other physical properties, has become a research hotspot. Light source, as an essential component for integrated optical system, is urgently needed. In this paper, we reported the realization of 1550-nm band on-chip LNOI microlasers based on erbium-doped LNOI ring cavities with loaded quality factors higher than one million, which were fabricated by using electron beam lithography and inductively coupled plasma reactive ion etching processes. These microlasers demonstrated a low pump threshold of ~20 {\mu}W and stable performance under the pump of a 980-nm band continuous laser. Comb-like laser spectra spanning from 1510 nm to 1580 nm were observed in high pump power regime, which lays the foundation of the realization of pulsed laser and frequency combs on rare-earth ion doped LNOI platform. This work has effectively promoted the development of on-chip integrated active LNOI devices.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Topological photonics and its topological edge state which can suppress scattering and immune defects set off a research boom. Recently, the quantum valley Hall effect (QVHE) with large valley Chern number and its multimode topological transmission have been realized, which greatly improve the mode density of the topological waveguide and its coupling efficiency with other photonic devices. The multifrequency QVHE and its topological transmission have been realized to increase the transmission capacity of topological waveguide, but multifrequency and multimode QVHE have not been realized simultaneously. In this Letter, the valley photonic crystal (VPC) is constructed with the Stampfli-triangle photonic crystal (STPC), and its degeneracies in the low-frequency and high-frequency bands are broken simultaneously to realize the multifrequency and multimode QVHE. The multifrequency and multimode topological transmission is realized through the U-shaped waveguide constructed with two VPCs with opposite valley Chern numbers. According to the bulk-edge correspondence principle, the Chern number is equal to the number of topological edge states or topological waveguide modes. Therefore, we can determine the valley Chern number of the VPC by the number of topological edge states or topological waveguide modes, further determine the realization of large valley Chern number. These results provide new ideas for high-efficiency and high-capacity optical transmission and communication devices and their integration, and broaden the application range of topological edge states.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Microcavity lasers based on erbium-doped lithium niobate on insulator (LNOI), which are key devices for LNOI integrated photonics, have attracted much attention recently. In this Letter, we report the realization of a C-band single-mode laser using Vernier effect in two coupled Erbium-doped LNOI microrings with different radii under the pump of a 980-nm continuous laser. The laser, operating stably over a large range of pumping power, has a pump threshold of ~200 {\mu}W and a side-mode suppression ratio exceeding 26 dB. The high-performance LNOI single-mode laser will promote the development of lithium niobate integrated photonics.