Researchers from the State Key Laboratory of Advanced Optical Communication Systems and Networks at Peking University, led by Professor Ya Cheng, have made significant strides in the development of highly efficient multi-chromatic Raman microlasers. Their work, published in the journal Nature Communications, presents a novel approach to creating on-chip coherent light sources with broad bandwidth and flexible tunability, which could have profound implications for the energy sector.
The team’s study focuses on the integration of stimulated Raman scattering (SRS) and second-order nonlinearity in non-centrosymmetric photonic microresonators. By leveraging cavity polygon modes within an X-cut thin-film lithium niobate microdisk, they achieved highly efficient multi-chromatic Raman microlasers. Specifically, they excited high-Q square modes with two parallel sides oriented perpendicularly relative to the optical axis of the lithium niobate crystal. These modes enhance mode-field overlap and improve phase matching, crucial for Raman-quadratic nonlinear interactions.
The experimental results demonstrated significant advancements in multi-wavelength laser generation. Forward stimulated Raman laser signals exhibited a high conversion efficiency of up to 65.02% and an impressively narrow integral linewidth of only 5.2 kHz. The system also enabled the generation of multi-wavelength Raman-quadratic laser signals across the ~800 nm and ~530 nm spectral bands. Notably, an absolute conversion efficiency of 1.33% for the 797.4-nm Raman laser was achieved at a pump power of just 1.07 mW.
This research extends the application scope of cavity polygon modes from single second/third-order nonlinear optical processes to cascaded processes. It establishes a foundation for realizing high-efficiency on-chip multi-chromatic laser sources with versatile functionalities. For the energy sector, these advancements could lead to more efficient and compact laser systems for various applications, including sensing, communications, and industrial processes. The ability to generate multiple wavelengths with high efficiency and low power consumption could also contribute to the development of more advanced and sustainable energy technologies.
Source: Nature Communications, “Highly efficient multi-chromatic Raman microlasers from cavity polygon modes on thin-film lithium niobate platform” by Yixuan Yang et al.
This article is based on research available at arXiv.