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We have developed an orthogonal digital demodulation scheme for Pound-Drever-Hall (PDH) frequency locking systems using the field-programmable gate array (FPGA). This scheme enhances the error model by incorporating crystal birefringence theory. Our approach mitigates the impact of laser polarization deviation and environmental interference on the phase instability of the photoelectric detector (PD) output signal by separating the effective amplitude signal from interfering phase information using narrowband signal decomposition and orthogonal baseband transformation theory. Additionally, we introduced a frequency lock-point localization algorithm for precise frequency stabilization in complex environments. Our research results show a significant reduction in maximum error from approximately 200 Hz in traditional schemes to around 100 Hz, while also stabilizing the signal's linear range.
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http://dx.doi.org/10.1364/OE.557725 | DOI Listing |
PeerJ
August 2025
Department of Spinal Surgery, Qingdao Municipal Hospital Group, Qingdao, Shandong Province, China.
Background: Adjacent segment disease (ASD) has become one of the most common complications after lumbar interbody fusion. To date, there have been few reports on the radiological effects between oblique lateral interbody fusion (OLIF) and minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) in lumbar degenerative diseases adjacent to the superior and inferior segments.
Method: The data of patients treated with OLIF or MIS-TLIF due to L4/5 degenerative lumbar diseases from October 2018 to March 2022 were retrospectively analyzed.
Rev 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 have developed an orthogonal digital demodulation scheme for Pound-Drever-Hall (PDH) frequency locking systems using the field-programmable gate array (FPGA). This scheme enhances the error model by incorporating crystal birefringence theory. Our approach mitigates the impact of laser polarization deviation and environmental interference on the phase instability of the photoelectric detector (PD) output signal by separating the effective amplitude signal from interfering phase information using narrowband signal decomposition and orthogonal baseband transformation theory.
View Article and Find Full Text PDFRev Sci Instrum
July 2025
Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China.
To achieve high performance ultra-stable laser (USL), multiple locking loops are required to operate simultaneously, including such as Pound-Drever-Hall (PDH), fiber noise cancellation (FNC), and light power stabilization (LPS). In this paper, a highly integrated multi-loop auto-locking system designed for USLs is demonstrated using fully digital electronics. The auto-locking process is implemented using a field programmable gate array with high-speed and high precision analog-to-digital and digital-to-analog converters.
View Article and Find Full Text PDFCell Death Dis
July 2025
Department of Pharmacology and International Cancer Center, Guangdong Provincial Key Laboratory of Regional Immunity and Diseases, Shenzhen University Medical School, Shenzhen, China.
Breast cancer (BC) is the most common tumor worldwide and it has been recognized that up to one third of BC patients have co-existing diabetes mellitus (DM) (BC-DM). Although many observational studies have indicated an association between DM and BC, the causal relationship of DM and BC prognosis remained uncertain and the molecular mechanisms underlying BC-DM are largely unclear. In this study, we used causal inference methods, including g-computation (GC), inverse probability of treatment weighting (IPTW), targeted maximum likelihood estimation (TMLE), and TMLE-super learner (TMLE-SL), to comprehensively analyze the association of DM with BC mortality in a cohort of 3386 BC patients.
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