研究目的
Investigating the manipulation of the second harmonic (SH) beams in nanophotonic waveguides using diffraction gratings to enhance the detection and conversion efficiency of SH signals.
研究成果
The integration of diffraction gratings with nanophotonic waveguides effectively manipulates the beam at the SH frequency, redirecting the radiation direction of SH light and enhancing the collection efficiency. This approach allows for the detection of SHG from co-propagating modes in high-loss waveguides and enables continuous beam steering by varying the pump wavelength. The findings contribute to the development of efficient nonlinear coherent light sources and integrated nonlinear nanophotonic devices.
研究不足
The study is limited by the propagation losses in the waveguide at the SH frequency, which affects the efficiency of SHG from co-propagating modes. The design could be optimized by adjusting the duty cycles of the grating or the phase difference between adjacent grating teeth to enhance coupling efficiency.
1：Experimental Design and Method Selection:
The study involved the integration of diffraction gratings with nanophotonic waveguides to manipulate the wavefront of SH beams. Theoretical models and momentum conservation equations were employed to predict the emission angles of SH signals.
2：Sample Selection and Data Sources:
Single-crystalline gold plates and CdSe nanobelts were used. The gold plates were synthesized via a wet-chemical procedure, and CdSe nanobelts were synthesized by chemical vapor deposition.
3：List of Experimental Equipment and Materials:
A wavelength tunable picosecond laser, an objective lens (Olympus, 100×), bandpass filters (380 – 420 nm), and a spectrometer were used for SHG measurements.
4：Experimental Procedures and Operational Workflow:
The CdSe nanobelts were transferred onto gold gratings using a mechanical transfer approach. SHG was excited by focusing a laser on the edge of the nanobelt, and the generated SH signal was collected and analyzed.
5：Data Analysis Methods:
The emission angles of SH signals were measured using Fourier imaging. The conversion efficiency and power dependence of SHG were analyzed to verify the nonlinear process.
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