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We present a simple and effective method for frequency locking a laser source to a free-space-coupled whispering-gallery-mode cavity. The scheme relies on the interference of spatial modes contained in the light scattered by the cavity, where low- and high-order modes are simultaneously excited. A dispersion-shaped signal proportional to the imaginary component of the resonant optical field is simply generated by spatial filtering of the scattered light. Locking of a diode laser to the equatorial modes of a liquid droplet resonator is demonstrated using this scheme, and its performance is compared to the Pound-Drever-Hall technique. This new approach makes laser-frequency locking straightforward and shows a number of advantages, including robustness, low cost, and no need for sophisticated optical and electronic components.
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http://dx.doi.org/10.1364/OL.41.000650 | DOI Listing |
Vet Sci
August 2025
ASA Campus Joint Laboratory, ASA Research Division, Department of Experimental and Clinical Biomedical Sciences, University of Florence, 50134 Florence, Italy.
Periodontal disease is a prevalent condition in companion animals. It is crucial to prevent the plaque and bacteria on tooth surfaces to avoid gingivitis and the more harmful periodontitis. The aim of the present study was to assess the impact of MLS laser treatment on the bacterial load by analyzing the gingival swabs of a total of 16 owned dogs with no history of dental disease that were selected from a cohort of patients admitted for plaque removal and dental hygiene procedures.
View Article and Find Full Text PDFLaser wavelength stabilization enables high-stable lasers to drive fundamental research and cutting-edge technologies. Advancements in such lasers now prioritize enhanced portability and reduced cost. In this Letter, we report a frequency-stability-enhanced, well-packaged non-planar ring oscillator laser at 1064 nm, by stabilizing its beat signal power of the dual-frequency laser inside the cavity.
View Article and Find Full Text PDFUltra-low-phase-noise photonic microwave generation and high-precision laser frequency determination are critical for advanced applications, such as radar, communication, and spectroscopy. Here, we demonstrate a monolithic nonplanar ring oscillator dual-frequency laser (NPRO-DFL) at 1064 nm that simultaneously generates ultra-stable photonic microwaves and enables sub-MHz laser frequency readout. By actively phase-locking the laser intracavity dual-frequency beat signal (equal to cavity free spectral range) to an ultra-stable oscillator via piezo control, we suppress the phase noise of the 5.
View Article and Find Full Text PDFRev Sci Instrum
August 2025
MOE Key Laboratory of TianQin Mission, TianQin Research Center for Gravitational Physics and School of Physics and Astronomy, Frontiers Science Center for TianQin, CNSA Research Center for Gravitational Waves, Sun Yat-sen University (Zhuhai Campus), Zhuhai 519082, China.
We present an advanced digital controller developed for laser frequency stabilization systems. A fully digital Pound-Drever-Hall (PDH) control scheme is implemented through direct digitization of the modulated optical signal, which is then demodulated in the digital domain and employs an inner-outer loop control module to lock the laser frequency to the cavity resonance. The design features automatic locking and relocking, where complex logic for signal verification and time-consuming monitoring is implemented using a state machine, thus enabling the system to automatically recover and prevent the locking procedure from getting stuck in a particular step.
View Article and Find Full Text PDFWe conduct a theoretical and experimental analysis for a self-referencing phase-lock module based on the delay-unbalanced Mach-Zehnder interferometer (UMZI) and optical phase-locked loop (OPLL). The self-referencing phase-lock module can be integrated with any system, allowing for linewidth narrowing and improved short-term laser stability without affecting the performance of the original system. In this paper, the laser noise detection principle based on UMZI is analyzed, accompanied by the development of UMZI response simulations and OPLL parameter design methods.
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