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Stabilizing diode laser to 1?Hz-level Allan deviation with atomic spectroscopy for Rb four-level active optical frequency standard
摘要： We achieve a compact ultra-stable 420 nm blue diode laser system by immediately stabilizing the laser on the hyperfine transition line of Rb atom. The Allan deviation of the residual error signal reaches 1 Hz-level Allan deviation within 1 s averaging time, and the fractional frequency Allan deviation is 1.4 × 10?15∕√?? , which shows the best result of frequency-stabilized lasers based on the atomic spectroscopy without Pound–Drever–Hall (PDH) system. The signal-to-noise ratio of the atomic spectroscopy is evaluated to be 3,000,000 from the Allan deviation formula, which is the highest record, to the best of our knowledge. The frequency noise suppression characterization is demonstrated and the maximal noise suppression can be near 40 dB at 6 Hz. As a good candidate of pumping source, the ultra-stable 420 nm diode laser is successfully used in our Rb four-level active optical frequency standard system. The method can be easily extended to other wavelengths ultra-stable lasers with a Allan deviation of 10?15 level retaining an atomic reference with low cost and low complexity while in the absence of an expensive and complicated PDH system.
关键词： ultra-stable laser,Rb four-level active optical frequency standard,atomic spectroscopy,Allan deviation,frequency noise suppression
更新于2025-09-19 17:13:59
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Multipoint and energy-equal fiber-optic laser-ultrasonic actuator based on peanut-shaped structures
摘要： This paper introduces the parabolic variance (PVAR), a wavelet variance similar to the Allan variance (AVAR), based on the linear regression (LR) of phase data. The companion article arXiv:1506.05009 [physics.ins-det] details the Ω frequency counter, which implements the LR estimate. The PVAR combines the advantages of AVAR and modified AVAR (MVAR). PVAR is good for long-term analysis because the wavelet spans over 2τ, the same as the AVAR wavelet, and good for short-term analysis because the response to white and flicker PM is 1/τ3 and 1/τ2, the same as the MVAR. After setting the theoretical framework, we study the degrees of freedom and the confidence interval for the most common noise types. Then, we focus on the detection of a weak noise process at the transition—or corner—where a faster process rolls off. This new perspective raises the question of which variance detects the weak process with the shortest data record. Our simulations show that PVAR is a fortunate tradeoff. PVAR is superior to MVAR in all cases, exhibits the best ability to divide between fast noise phenomena (up to flicker FM), and is almost as good as AVAR for the detection of random walk and drift.
关键词： frequency stability,flicker,atomic frequency standard,Allan variance,phase noise,frequency noise,oscillator,measurement uncertainty
更新于2025-09-16 10:30:52
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[IEEE 2019 International Conference on Electrical and Computing Technologies and Applications (ICECTA) - Ras Al Khaimah, United Arab Emirates (2019.11.19-2019.11.21)] 2019 International Conference on Electrical and Computing Technologies and Applications (ICECTA) - Miniature Dual-Band Band-Pass Filter Using Slotted Ring Resonators and Coupled lines for L and S Bands Communication
摘要： This paper introduces the parabolic variance (PVAR), a wavelet variance similar to the Allan variance (AVAR), based on the linear regression (LR) of phase data. The companion article arXiv:1506.05009 [physics.ins-det] details the Ω frequency counter, which implements the LR estimate. The PVAR combines the advantages of AVAR and modified AVAR (MVAR). PVAR is good for long-term analysis because the wavelet spans over 2τ, the same as the AVAR wavelet, and good for short-term analysis because the response to white and flicker PM is 1/τ3 and 1/τ2, the same as the MVAR. After setting the theoretical framework, we study the degrees of freedom and the confidence interval for the most common noise types. Then, we focus on the detection of a weak noise process at the transition—or corner—where a faster process rolls off. This new perspective raises the question of which variance detects the weak process with the shortest data record. Our simulations show that PVAR is a fortunate tradeoff. PVAR is superior to MVAR in all cases, exhibits the best ability to divide between fast noise phenomena (up to flicker FM), and is almost as good as AVAR for the detection of random walk and drift.
关键词： atomic frequency standard,frequency noise,measurement uncertainty,oscillator,frequency stability,Allan variance,flicker,phase noise
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - St. Petersburg, Russia (2019.10.17-2019.10.18)] 2019 IEEE International Conference on Electrical Engineering and Photonics (EExPolytech) - Laser Frequency Noise Measurement by Forming an Interference Signal with Subcarrier Frequency
摘要： The paper presents a method for measuring laser frequency noise spectrum with the use of unbalanced fiber-optic interferometer and auxiliary phase modulation, forming a subcarrier signal at the interferometer output. The main features of the proposed method are analyzed. The paper also presents the results of experimental validation of the proposed method by measuring laser frequency noise of a high-coherent optical fiber laser.
关键词： laser frequency noise spectrum,laser frequency noise,coherent laser,fiber-optic interferometer
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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Method for Measuring Laser Frequency Noise
摘要： We have analyzed the characteristic features and problems in the major approaches to measurement of laser frequency noise. We propose a method in which we use an unbalanced fiber-optic interferometer, generation at the optical system output of a signal for a subcarrier of the frequency, phase-modulated by fluctuations in the laser frequency, and measurement of the spectrum for this signal. The proposed approach is distinguished by relative simplicity and accessibility, and does not require using uncommon specialized instruments and complicated specific procedures.
关键词： laser noise spectrum,laser frequency noise,coherent laser source,fiber-optic interferometer
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 4th Optoelectronics Global Conference (OGC) - Shenzhen, China (2019.9.3-2019.9.6)] 2019 IEEE 4th Optoelectronics Global Conference (OGC) - Quality Assessment of 980 nm GaAs Based Laser Diodes with Use of Low-Frequency Noise Measurements
摘要： Low-frequency noise has always been a fast and non-destructive tool to characterise the performance and quality of materials and electrical devices. In this paper, a non- destructive method of predicting reliability was introduced for 980 nm GaAs based semiconductor laser diodes. Measurement and analysis were carried out for the noise and transport characteristics of forward voltage biases. The results demonstrated a close relationship between LD quality and the characteristic parameters of low-frequency noise such as frequency exponent, noise intensity and amplitude.
关键词： low-frequency noise,frequency exponent,forward bias,laser diodes,GaAs substrate
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) - Rate Equation Modeling of Interband Cascade Lasers
摘要： Interband cascade lasers (ICLs) are power-efficient mid-infrared laser sources for applications in sensing of numerous molecules and in free-space optical communications. The static performances of ICLs including the lasing threshold and the output power have been significantly improved since its first demonstration by R. Yang [1]. GaSb-based ICLs have optimal performance in the spectral range of 3-4 μm, which is hard to reach for the quantum cascade laser counterpart [2]. This work proposes a rate equation model for studying dynamical characteristics of ICLs including the intensity modulation (IM) response, the relative intensity noise (RIN), and the frequency noise (FN). Taking into account carrier dynamics in the W-shape active region while ignoring those in the electron and hole injectors [3], the rate equations for the carrier number N, the photon number S, and the phase φ of the electric field read. Based on the standard small-signal analysis of the above rate equations, we obtain analytical formulas for IM response, RIN, and FN, respectively (not shown in this paper). The inset of Fig. 1(a) shows that ICLs exhibit an underdamped resonance peak in the IM response at a low pump current, and the modulation bandwidth increases with increasing pump current as conventional laser diodes. Figure 1(a) proves that more gain stages are desirable for enhancing the modulation bandwidth of ICLs. The inset of Fig. 1(b) shows that the RIN is raised at the resonance frequency, while a small stage number reduces the RIN in the whole spectral range. Figure 1(b) demonstrates that the RIN at the low-frequency range (<1.0 GHz) increases nonlinearly with the gain stage number. The inset of Fig. 1(c) shows that the FN of ICLs is raised at the resonance frequency, while a small stage number reduces the FN in the whole spectral range as well. The intrinsic spectral linewidth of ICLs in Fig. 1(c) is obtained from the low-frequency FN level. It is found that the intrinsic linewidth linearly increases with the gain stage number, which is consistent with the derived analytical formula. In summary, we theoretically prove that a large gain stage number is desirable for enhancing the modulation bandwidth, while a small stage number is favorable to reduce both the RIN and the FN/linewidth of ICLs.
关键词： Interband cascade lasers,rate equation model,frequency noise,intensity modulation,relative intensity noise
更新于2025-09-12 10:27:22
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Cooled Silicon-On-Insulator Diode Thermometer: Toward THz Passive Imaging
摘要： Terahertz passive imaging requires high sensitivity detectors, with Minimum Detectable Power (MDP) under the picowatt range. An antenna-coupled cooled microbolometer, incorporating a lateral PiN-like diode as thermometer, could represent a solution. In a first step, such diode performances have to be investigated, especially the temperature coefficient of current (TCC) and the low frequency noise. Prototypes were fabricated on Silicon-On-Insulator (SOI) 4” wafers with 50-nm active silicon layer. I-V and noise measurements down to 81K were useful to derive the electrical MDP of the future bolometer, already reaching 6.6 pW at 10 frames per second.
关键词： low frequency noise,microbolometer,Minimum Detectable Power,PiN diode,temperature coefficient of current,Silicon-On-Insulator,Terahertz passive imaging
更新于2025-09-12 10:27:22
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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) - Characterization, Integration and Operation of a 100-W Solid State Amplifier in the Advanced-VIRGO Pre-Stabilized Laser System
摘要： VIRGO is a 3-km-arm laser interferometer for gravitational wave detection in the 20 Hz - 5 kHz frequency band. Its second-generation version, Advanced VIRGO, aims at reducing the detector noise by a factor of ten compared to the first generation, with the progressive deployment of new technologies and equipment. The first detections of gravitational waves with VIRGO were made in August 2017. For its next scientific observations with an increased sensitivity, a pre-stabilized laser system twice as powerful has been developed. It comprises a new 100-W solid-state amplifier pumped at 878.7 nm. It is the first time such amplifier is integrated in a gravitational wave detector, LIGO detectors using a 70 W amplifier pumped at 808 nm. Power noise, long term power stability, frequency noise, beam jitter and transverse mode quality have been extensively studied and compared to Advanced VIRGO requirements.
关键词： beam jitter,solid-state amplifier,Advanced VIRGO,power noise,laser interferometer,frequency noise,gravitational wave detection
更新于2025-09-11 14:15:04