RESUMEN
State-of-the-art optical cavities are pivotal in pushing the envelope of laser frequency stability below 10-16. This is often achieved by extending the cavity length or cooling the system to cryogenic temperatures to reduce the thermal noise floor. In our study, we present a 30-cm-long cavity that operates at room temperature and is outfitted with crystalline coatings. The system has a predicted ultralow thermal noise floor of 4.4 × 10-17, comparable to what is observed in cryogenic silicon cavities. A 1397-nm laser is stabilized in this advanced cavity, and the stable frequency is then transferred to the clock transition in strontium optical lattice clocks via a frequency-doubling process. We have meticulously minimized and assessed the technical noise contributions through comparisons with an ultrastable reference laser that is locked to a commercially available 30-cm cavity. The frequency instability of the system is rigorously evaluated using a three-cornered-hat method. The results demonstrate that the laser frequency instability remains below 2 × 10-16 for averaging times ranging from 1 to 50 s. These findings underscore the significant potential of room-temperature cavities with crystalline coatings in high-precision metrology and pave the way for further improvements in optical lattice clocks.
RESUMEN
Optical thin films with high-reflectivity (HR) are essential for applications in quantum precision measurements. In this work, we propose a coating technique based on reactive magnetron sputtering with RF-induced substrate bias to fabricate HR-optical thin films. First, atomically flat SiO2 and Ta2O5 layers have been demonstrated due to the assistance of radio-frequency plasma during the coating process. Second, a distributed Bragg reflector (DBR) mirror with an HR of â¼99.999 328% centered at 1397 nm has been realized. The DBR structure is air-H{LH}19-substrate, in which the L and H denote a single layer of SiO2 with a thickness of 237.8 nm and a single layer of Ta2O5 with a thickness of 171.6 nm, respectively. This novel coating method would facilitate the development of HR reflectors and promote their wide applications in precision measurements.
RESUMEN
BACKGROUND: Persistent suspicion of prostate cancer (PCa) due to a rising prostate-specific antigen (PSA) level after repeated negative biopsies is a serious challenge in clinical practice. AIM: To determine the role of Hiraoka's transurethral detachment of the prostate (TUDP) combined with biopsy of the peripheral zone during the same session in patients with repeated negative biopsies in the diagnosis of PCa. METHODS: We retrospectively evaluated the records of 10 patients who were eligible for inclusion in our hospital between December 2012 and August 2017. Patient demographics, a family history of PCa, the number of biopsies, prostate volume, pathological examination, and perioperative PSA level were obtained. RESULTS: Two of 10 patients were pathologically diagnosed with PCa after surgery; the Gleason scores were 4 + 4 and 4 + 3, respectively. Both patients subsequently underwent laparoscopic radical prostatectomy. The median PSA levels preoperatively, and 3 mo and 1 year postoperatively in the other eight patients who were diagnosed with benign prostate hyperplasia after surgery were 19.10 ng/mL, 1.10 ng/mL, and 1.15 ng/mL, respectively. The adjusted P values of the 3-mo and 1-year post-operative PSA level vs pre-operative PSA level were 0.003 and 0.026, respectively. None of the patients had increased PSA levels or PCa detected after a median 35 mo of follow-up. CONCLUSION: TUDP combined with peripheral zone biopsy may improve the detection rate of PCa in patients with repeated negative biopsies. The PSA level declined rapidly in patients who had negative pathological examinations after TUDP, which remained stable 1 year after surgery.