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System Design for High-Capacity Unrepeatered Optical Transmission
摘要： By basing the figure of merit on the joint evaluation of signal BER and OSNR, the design of single-carrier 400G unrepeatered optical systems using remote optically-pumped amplifiers (ROPAs) with dedicated delivery fiber is discussed and analyzed in this work. Simulation results show very good agreement with experimental measurements, proving the effectiveness of the proposed approach in critical transmission situations.
关键词： remote optically-pumped amplifier (ROPA),distributed Raman amplifier (DRA),optical system design,Unrepeatered coherent transmission
更新于2025-09-23 15:22:29
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Sources of heading errors in optically pumped magnetometers operated in the Earth's magnetic field
摘要： When optically pumped magnetometers are aimed for use in the Earth’s magnetic field, the orientation of the sensor to the field direction is of special importance to achieve accurate measurement results. Measurement errors and inaccuracies related to the heading of the sensor can be an even more severe problem in the case of special operational configurations, such as the use of strong off-resonant pumping. We systematically study the main contributions to the heading error in systems that promise high magnetic field resolutions at the Earth’s magnetic field strengths, namely the nonlinear Zeeman splitting and the orientation-dependent light shift. The good correspondence of our theoretical analysis to experimental data demonstrates that both of these effects are related to a heading-dependent modification of the interaction between the laser light and the dipole moment of the atoms. Also, our results promise a compensation of both effects using a combination of clockwise and counterclockwise circular polarization.
关键词： optically pumped magnetometers,circular polarization,Earth's magnetic field,light shift,nonlinear Zeeman splitting,heading error
更新于2025-09-23 15:22:29
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Magnetoencephalography with optically pumped 4He magnetometers at ambient temperature
摘要： In this paper, we present the first proof of concept confirming the possibility to record magnetoencephalographic (MEG) signals with Optically Pumped Magnetometers (OPMs) based on the parametric resonance of 4He atoms. The main advantage of this kind of OPM is the possibility to provide a tri-axis vector measurement of the magnetic field at room-temperature (the 4He vapor is neither cooled nor heated). The sensor achieves a sensitivity of 210 fT/√Hz in the bandwidth [2 Hz - 300 Hz]. MEG simulation studies with a brain phantom were cross-validated with real MEG measurements on a healthy subject. For both studies, MEG signal was recorded consecutively with OPMs and Superconducting Quantum Interference Devices (SQUIDs) used as reference sensors. For healthy subject MEG recordings, three MEG proofs of concept were carried out: auditory and visual evoked fields (AEF, VEF), and spontaneous activity. M100 peaks have been detected on evoked responses recorded by both OPMs and SQUIDs with no latency. Concerning spontaneous activity, an attenuation of the signal power between 8-12 Hz (alpha band) related to eyes opening has been observed with OPM similarly to SQUID. All these results confirm that the room temperature vector 4He OPMs can record MEG signals and provide reliable information on brain activity.
关键词： visual evoked field,Optically pumped magnetometer,vector measurement,magnetoencephalography,spontaneous activity,auditory evoked field,room temperature,Helium 4
更新于2025-09-23 15:21:21
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The efficacy and safety of a 577a??nm higha??power optically pumped semiconductor laser in the treatment of postacne erythema
摘要： Background: Postacne erythema (PAE) is a common sequela of inflammatory acne vulgaris. Treatment of which has been challenging due to limited options available and the variability of results for each modality. Recently, a 577-nm high-power optically pumped semiconductor laser (HOPSL) initially developed for vascular lesions, has shown promising results for the treatment of PAE. Objective: To evaluate the efficacy and safety of 577-nm HOPSL in the treatment of postacne erythema. Materials and Methods: This was a split-face, randomized controlled trial pilot study. Twenty-one patients with PAE on both sides of their face were enrolled. Each subject’s face sides were randomly assigned to either receive 577-nm HOPSL treatment (QuadroStar PROTM, Asclepion Laser Technologies, Jena, Germany) using the scanner handpiece, 1mm spot size, 80% coverage, 12-15 J/cm2, 30 ms, 2 passes for 3 sessions at 1-month intervals, or no treatment at all. Outcome measures such as overall improvement, the Erythema Index (EI) and Melanin Index (MI) from 3 different areas on both treatment and control sides were assessed at baseline, and 1-month follow-up after each treatment session. Side effects including pain, erythema, swelling, and crusting were also recorded. Results: Upon completion of the treatment period, the mean EI was significantly decreased in both treated and non-treated sides of the face (p<0.001 and p=0.001, respectively). The laser-treated sides already demonstrated significant reduction in the mean EI compared to non-treated sides at 1 month after the 2nd treatment (p=0.007). The mean MI of both sides; however, did not show any statistically significant differences from baseline, and likewise when comparing between sides. Patients reported more improvement on laser-treated sides compared to non-treated sides. Reported side effects were limited to mild discomfort during treatment and transient facial erythema lasting approximately 30 minutes. Conclusion: Patients who received treatment with the 577-nm HOPSL had better outcomes with minimal side effects at 1 month after 2 treatments as compared to those who did not receive any treatment. Therefore, the 577-nm HOPSL may be considered as an effective adjuvant treatment for PAE and early erythematous atrophic scars.
关键词： Vascular-specific laser,577-nm high-power optically pumped semiconductor laser (HOPSL),Postacne erythema
更新于2025-09-23 15:21:01
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Pick and Place Distributed Feedback Lasers Using Organic Single Crystals
摘要： Organic single crystals are of interest for optoelectronic applications due to their highly ordered molecular stacking and small defect concentration, giving the possibility of high mobility and luminescence efficiency. To achieve lasing in large flat single crystals, a simple 'pick and place' method of mounting organic single crystals onto distributed feedback gratings is demonstrated. Efficient lasing is achieved with three kinds of active organic single crystals, indicating the potential for broad application of the method for making single crystal lasers using distributed feedback gratings. Detailed investigations of the anisotropic refractive index and waveguide simulations further confirm that distributed feedback can provide efficient ways of fabricating organic single crystal lasers.
关键词： organic semiconductor optoelectronics,solid-state lasers,optically pumped lasers
更新于2025-09-23 15:19:57
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018) - Nagoya (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Optically Pumped Mixing in Photonically Integrated Uni- Travelling Carrier Photodiode
摘要： We report the first demonstration of optically pumped mixing using a monolithically integrated photonic chip. On that chip, uni-traveling carrier photodiodes (UTC-PDs) were monolithically integrated with two lasers to generate the optical heterodyne that will drive the optically pumped mixing. The two DFB lasers wavelength spacing was tuneable from 70.5 GHz to 92.4 GHz. When an RF signal at 70 GHz was supplied to the UTC-PD with the optimum voltage bias, the UTC-PD successfully down-converted the RF signal to an intermediate frequency (IF) that was tuneable from 0.5 GHz to 16.4 GHz. These results demonstrate the potential of this photonic integrated circuit in spectroscopy, sensing and as millimeter wave wireless receivers.
关键词： photonic integrated circuit,heterodyne,millimeter wave,optically pumped mixing,uni-traveling carrier photodiode
更新于2025-09-19 17:13:59
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Effect of Ar(3p <sup>5</sup> 4p; 2p)+M → Ar(3p <sup>5</sup> 4s; 1s)+M branching ratio on optically pumped rare gas laser performance
摘要： Optically pumped rare gas laser performance is analyzed as a function of the Ar(3p54p; 2p) + M → Ar(3p54s; 1s) + M branching ratios. Due to the uncertainty in the branching ratios, a sensitivity study is performed to determine the effect on output and absorbed pump laser intensities. The analysis is performed using a radio frequency dielectric barrier discharge as the source of metastable production for a variety of Argon in Helium mixtures over pressures ranging from 200 to 500 Torr. Peak output laser intensities show a factor of 7 increase as the branching ratio is increased from 0.25 to 1.00. The collection of Ar* in Ar(1s4) is inversely proportional to the branching ratio and decreases output laser intensity by reducing the density of species directly involved with lasing.
关键词： Argon,Helium,branching ratio,radio frequency dielectric barrier discharge,metastable production,optically pumped rare gas laser
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Thermal Noise in Optically Pumped DF-VECSELs
摘要： Over the last decades, the low noise properties of Vertical–External–Cavity Surface–Emitting Lasers (VECSELs) have aroused interest for various applications. The dual–frequency (DF) VECSELs can generate a very low noise RF signal resulting from the beatnote of two orthogonal linear polarizations as sketched in Fig.1(a). For example, the very high spectral purity and class–A operation of DF–VECSELs are of interest for ultrastable atomic clocks [1] or microwave electronics for optically-carried RF signal processing or wide-band RADARs. The sources of noise of optically pumped VECSELs are well identi?ed : (i) the intensity noise induced by the pump through the laser dynamics, (ii) the spontaneous emission contribution, (iii) technical noises such as mechanical vibrations, and (iv) the thermal noise. The two ?rst sources of noise are well modeled and understood. But in [2] a simple second–order low-pass ?lter behaviour is assumed for the thermal contribution to the frequency noise power spectral density (PSD) spectra. Yet, de?ning unequivocally a cut–off frequency is not obvious since different time scales are actually involved. Moreover, this over–simpli?ed model fails at low frequencies in [3] as displayed in Fig.1(b). Indeed, below 200 kHz the slope of the beatnote phase–noise spectrum of a DF–VECSEL at 852 nm obeys a f ?3 scaling law instead of the f ?4 expected behaviour. The aim of the present work is to microscopically model the thermal noise contribution. First, we describe the layers of the optically pumped emitting–surface, which is glued to a Peltier cooler. The heat equations take into account transverse and longitudinal diffusion processes. Assuming a gaussian pro?le for the pump, we obtain the temperature ?eld inside the structure using Hankel transformation formalism and we investigate the transient thermal response. The pump intensity ?uctuations induce heat ?uctuations inside the structure leading to changes of the refractive index and the material thermal–expansion, which are responsible for frequency ?uctuations of the laser mode. We ?nd an analytical expression of the frequency noise PSD induced by these thermo-optic effects, which allows to model the beatnote phase noise PSD of DF-VECSELs. We ?nd a very good agreement with the f ?3 slope of the experimental datas and we evidence the fundamental thermal ?uctuations contribution at room temperature. Such thermodynamics ?uctuations were already investigated for VCSEL structures in [4], starting from a stochastic heat equation. We extend it to a full study of the frequency noise PSD spectrum for DF-VECSELs. We obtain a fully analytical expression and discuss its validity.
关键词： Thermal noise,frequency noise PSD,thermal fluctuations,optically pumped,DF-VECSELs
更新于2025-09-16 10:30:52
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[IEEE 2019 Joint Conference of the IEEE International Frequency Control Symposium anEuropean Frequency and Time Forum (EFTF/IFC) - Orlando, FL, USA (2019.4.14-2019.4.18)] 2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC) - The Compact Laser System for Pulsed Optically Pumped Rubidium Atomic Clock
摘要： In this paper, we propose an implementation of the compact laser system for POP rubidium atomic clock. The compact system consists of the miniaturized optical platform and the laser driving and control electronic module, and the two parts with the same length and width are stacked together to ensure the output laser beam is exactly incident to rubidium vapor cell in physics package of the clock. (1) The miniaturized optical system adopts integration design milling all the pedestals of optical components on the bottom board of the platform with a volume of 30cm×17.5cm×5.8cm. It mainly includes a DBR diode laser as laser source, AOM as optical switching, sub-Doppler spectroscopy optical path, and optical expansion lens. (2) Laser driving and control electronic module mainly includes the high-precision driving current source, temperature control module, and the lock-in module (including PI and the error signal demodulating module). The temperature of the laser diode is set to 20.1℃, with ±0.001℃ fluctuation and the injected current is set around 180.2mA, with ±0.001mA control precision. The power of output laser is 40mW, with diameter 15mm. With sub-Doppler spectroscopy, the laser has been locked to rubidium transition line (795nm) more than 30 days and relocked within 1 second under unattended laboratory conditions, with power fluctuation less than 0.2% and power stability 5.57×10-4. The experimental results show that the portable compact laser system has strong robustness and reliance, which has an important significance in the engineering process of POP Rb atomic clock.
关键词： compact laser system,laser driving and control electronic module,optical platform,pulsed optically pumped rubidium atomic clock
更新于2025-09-16 10:30:52
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Optically Pumped Monolayer MoSe <sub/>2</sub> Excitonic Lasers from Whispering Gallery Mode Microcavities
摘要： Developing integrable, nanoscale, and low-energy-consumption lasers is a crucial step toward on-chip optical communications and computing technologies. The strong exciton-photon interaction emerged in monolayer transition metal dichalcogenides (TMDs) holds promise for engineering and integration. Herein we prepare the MoSe2/microsphere cavities excitonic lasers by placing SiO2 microspheres on top of monolayer MoSe2 film. By virtue of continuous wave exciting MoSe2/microsphere whispering-gallery-mode (WGM) cavities, we realize multiple excitonic WGM lasing in the emission wavelength range of ～750 nm to 875 nm at room temperature with tunable properties of free spectral range (FSR) and full width at half maximum (FWHM) by varying the microsphere size. Theoretical calculations based on finite element method (FEM) using COMSOL software were utilized to identify lasing modes and reveal the corresponding electric ?eld distribution. These findings help to deepen fundamental understanding of excitonic WGM lasing, and provide a promising research platform for integrable, scalable, and low-cost laser devices.
关键词： Whispering Gallery Mode Microcavities,Monolayer MoSe2,Optically Pumped,Excitonic Lasers
更新于2025-09-12 10:27:22