Pump Light Power Research Articles

Design of Fiber Laser Based on Erbium-ion

Erbium ions (Er3+) exhibit good characteristics of fiber lasers in the 1500-1550 nm band, including three-level systems, high tilt efficiency, and large emission cross sections. This article focuses on studying the spectral characteristics of erbium ions, simulating the power propagation equation of erbium-doped ion fiber lasers, and calculating the pump power threshold and output power. The findings of the simulation indicate that the laser begins to produce 10 W of pump optical power. The laser power hits 34.38 W and the oblique power is determined to be 38.20% as soon as the pump power exceeds 100 W. Experimental results show that when pump light propagates forward, the forward propagation power of the pump light will weaken, the forward propagation power of the signal light will increase, the reverse propagation of the signal light will weaken and the reverse propagation of the pump light will Transmission will also weaken, with directional transmission remaining largely unchanged. This study carried out numerical simulations on the experimental parameters of the fiber laser doped with Er3+and finally obtained the output power of pump light and signal light under these conditions, providing better data support for the preparation of 1500-1550 nm fiber laser doped with erbium ion.

Design of 1450-1500nm Bismuth-doped Fiber Laser

With the rapid development of information technology, people's demand for the transmission capacity of fiber optic communication networks is increasing. How to broaden the bandwidth of communication systems has become one of the key issues in the field of communication. Researchers have found that the operating bandwidth of amplifiers mainly limits the bandwidth of communication systems. Although multiple solutions have been proposed and implemented to address this issue, there are still many gaps in the design of full-band multi wavelength-related light sources. By studying the three-level system of bismuth ions, the rate equation and power transfer equation of a bismuth ion doped fiber laser are simulated, and the pump power threshold and output power are calculated. Using MATLAB for simulation experiments, the relationship between laser power and pump power, as well as their variation with propagation distance, were ultimately obtained. The simulation results show that under 830 pump lights, the pump light threshold power is 10W. After reaching the threshold power, the pump light power and laser power have a linear relationship, and as the propagation distance increases, the pump light power gradually decreases and the laser power gradually increases. The analysis shows that the power generated by the signal light in this band meets the theoretical standards, which verifies the correctness of the scheme.

Design and simulation implementation of bismuth-doped fiber laser

Rare-earth doped fibers are an important means of expanding the wavelength band of optical fibers. Currently, researchers aim to broaden the working wavelength band of optical fibers by doping with different rare-earth elements, thereby increasing the amount of information that can be transmitted. In this paper, a bismuth-doped fiber laser operating around 1300nm was designed. A basic physical model for implementing a bismuth-doped fiber laser was proposed based on the energy levels and transition processes of bismuth, rate, and power propagation equations. It was possible to determine the link between pump power and laser power at a wavelength of 1300 nm by modeling tests using the physical model. Additionally, the relationship between pump light and laser power in bismuth-doped fiber at different positions and propagation directions was analyzed. Suggestions for the future large-scale application of bismuth-doped fiber lasers around the 1300nm wavelength band were provided.

Suppression of Bias instability Induced by Fluctuations in Pump Light Power Density by Vapor Cell Temperature Optimization in Spin-Exchange Relaxation-Free Co-Magnetometers

Suppression of Bias instability Induced by Fluctuations in Pump Light Power Density by Vapor Cell Temperature Optimization in Spin-Exchange Relaxation-Free Co-Magnetometers

Comprehensive analysis on the magnetic field error of a K–Rb–21Ne comagnetometer with low-frequency bias magnetic field sensitivity

The spin-exchange relaxation-free comagnetometer (SERFC) is of important research value compared to existing high-precision gyroscopes because of its extremely high theoretical limit sensitivity and long-term stability, in which one significant limiting factor is the magnetic field error. First, the relationship between the magnetic field gradient and the nuclear spin relaxation mechanism is introduced into the frequency response and steady-state response models of SERFC. Then, a novel method for suppression of the low-frequency magnetic field error based on the modified bias magnetic field sensitivity model is proposed. Finally, the effectiveness of the proposed suppression methods is demonstrated by optimizing the cell temperature, pump light power, and compensation magnetic field gradient to increase the suppression factor by 72.19%, 20.24%, and 69.86%, and the corresponding bias instability increased by 55.41%, 20.84%, and 27.63%, respectively. This study contributes to improving the long-term zero bias stability of the SERFC.

Tunable all-optical liquid crystal lens based on the thermo-plasmonic effect

Surface plasmon resonance (SPR) thermal effects have been the focus of researchers lately and are commonly used in sensors, micro heaters in integrated circuits, and other applications. In this study, a new type of tunable all-optical liquid crystal (LC) lens is fabricated by employing the SPR thermal effects. Due to the absorption of pump light by gold nanoparticles, the generated heat is transferred to the surrounding LC layer, leading a radial gradient distribution of LC molecules. Passing a probe light through the center of the fabricated cell, a lens shaped optical phase retardation observed. The temperature increase with intensification of the pump light power has been numerically calculated. In addition, the focal length of the lens reduces from 157.8 to 13.1 cm during this process. The tunable all-optical LC lens is a fascinating new concept that could open up new horizons and has numerous applications. It has a simpler and cheaper structure compared to electronic lenses, provides greater stability than other all-optical counterparts, and allows for optical control of the focal length.

Nonzero-Order Resonances in Single-Beam Spin-Exchange Relaxation-Free Magnetometers

Zero-field optically pumped magnetometers operating in the spin-exchange relaxation-free (SERF) regime have been extensively studied, and usually depend on zeroth-order parametric resonance to measure the magnetic field. However, the studies conducted on this topic lack thorough analyses and in-depth discussion of nonzero-order magnetic resonances in single-beam SERF magnetometers. In this paper, we analyzed the nonzero-order resonance, especially the first-order resonance, based on a single-beam SERF magnetometer, and discussed its various applications. A comprehensive theoretical analysis and experiments were conducted with respect to multiple functions, including nonzero finite magnetic field measurements, spin polarization measurement, and in situ coil constant calibration. The results showed that first-order resonance can be utilized for nonzerofinite magnetic field measurements, and the spin polarization of alkali-metal atoms can be determined by measuring the slowing-down factor using the resonance condition. Furthermore, acquiring the first-order resonance point at an equivalent zero pump light power through fitting offers an approach for quick and precise in situ coil constant calibration. This study contributes to the applications of SERF magnetometers in nonzero finite magnetic fields.

A robust method for performance evaluation of the vapor cell for magnetometry

A robust performance evaluation method for vapor cells used in magnetometers is proposed in this work. The performance of the vapor cell determines the sensitivity of the magnetic measurement, which is the core parameter of a magnetometer. After establishing the relationship between intrinsic sensitivity and the total relaxation rate, the total relaxation rate of the vapor cell can be obtained to represent the intrinsic sensitivity of the magnetometer by fitting the parameters of the magnetic resonance experiments. The method for measurement of the total relaxation rate based on the magnetic resonance experiment proposed in this work is robust and insensitive to ambient noise. Experiments show that, compared with conventional sensitivity measurement, the total relaxation rate affected by magnetic noise below 0.9 nT, pump light frequency noise below 1.5 GHz, pump light power noise below 9%, probe light power noise below 3% and temperature fluctuation of 150 ± 3 °C deviates by less than 2% from the noise-free situation. This robust performance evaluation method for vapor cells is conducive to the construction of a multi-channel high-spatial-resolution cardio-encephalography system.

Red and green light generation in TPPLNOI ridge optical waveguide with 1550 nm picosecond laser

Periodically poled lithium niobate (PPLN) waveguides are a powerful platform for efficient frequency conversion. Conventional frequency doubling PPLN converters only generate second-harmonic light. However, we propose a trapezoidal periodically poled lithium niobate on insulator (TPPLNOI) ridge optical waveguide, simultaneously generating red and green light with 1550 nm picosecond laser by cascading second-harmonic generation and sum-frequency generation (SHG-SFG). According to the experimental data, we find that the second-harmonic (red light at 775 nm) and third-harmonic (green light at 517 nm) power increase with the pump light (1550 nm) power. We also verify experimentally that temperature can affect nonlinear frequency conversion of cascading SHG-SFG, and when the temperature increases from 20 °C to 70 °C, the normalized conversion efficiency of red light and green light rises from 154.79% W−1 cm −2, 129.24% W−1 cm −2 to 204.29% W−1 cm −2, 152.08% W−1 cm −2, respectively.

Efficient Optical Modulation of Exciton State Population in Monolayer MoS2 at Room Temperature.

The modulation of exciton energy and state density of layer-structured transition metal dichalcogenides (TMDs) is required for diverse optoelectronic device applications. Here, the spontaneous inversion of exciton state population in monolayer MoS2 is observed by turning the pump light power. The excitons prefer to exist in low energy state under low pump power, but reverse under high pump power. To discuss the mechanism in depth, we propose a semiclassical model by combining the rate equation and photo−exciton interaction. Considering the modifying of exciton−exciton annihilation, the spontaneous inversion of exciton state population is phenomenologically described.

Ultra-wide range and wavelength fixed trace gas detection technology based on single chamber multiplexing

The all-fiber photo-thermal interference (PTI) system based on hollow-core photonic crystal fiber (HC-PCF) has the advantages of wide dynamic range, ultra-sensitivity, and small volume, which is of great significance in gas trace analysis. Most of the previous PTI systems obtain the relationship between gas concentration and phase modulation by wavelength scanning and extracting the second harmonic signal absorbed by the gas. However, the residual modulation caused by the asynchronism between wavelength and modulation signal seriously affects the signal-to-noise ratio (SNR) and dynamic detection range of the system. In addition, wavelength scanning has limitations for detecting gas with irregular absorption lines. This paper proposes an all-fiber photo-thermal interference system with pump intensity external modulation. The system is not limited by the gas absorption line and has a high SNR. The factors affecting the dynamic range of the system are analyzed theoretically and experimentally. It is verified that increasing the injection gas pressure can significantly increase the detection limit of the system compared with increasing the pump light power. The redshift of the pump light can dramatically increase the detection limit of the system. A C2H2 gas trace system with the pump wavelength redshifted to 1530.41 nm was demonstrated. The detection lower limit of 9.24 ppm and an extensive dynamic detection range of five orders of magnitude were obtained.

Tunable Faraday effect in Graphene/SiO2/Ta2O5 layered structure using a pump He-Ne laser light

Faraday rotation spectrum of a Graphene/SiO2/Ta2O5 layered structure under an external magnetic field and a pump light of a He-Ne laser with the wavelength of 632.8 nm is investigated in the THz frequency region. The results showed that, when the pump light is turned off and the magnetic field strength is increased, the maximum Faraday rotation angle frequency shifts toward the higher frequencies, as well as, the value of the maximum Faraday rotation angle increases. Furthermore, for a constant external magnetic field, by increasing the pump light power, the value of Faraday rotation increases, and the maximum Faraday rotation frequency shifts toward the lower frequencies. However, the noticeable changes in the transmission spectrum were not observed by changing the magnetic field strength and the pump light power. These results would have potential applications in designing the magneto-optical devices with tuning property of the Faraday rotation using a pump He-Ne laser.

Tunable Nonlinearity in 2D Graphdiyne Oxide for High‐Performance All‐Optical Modulation

Abstract2D atomically thin graphdiyne oxide (GDYO) nanosheets (NSs) are synthesized, and their nonlinear modulation is investigated. Generally, improving the modulation depth (MD) of all‐optical modulation (AOM) requires a pump light with strong power, which limits the development of AOM technology in the design of low‐power loss devices. In this study, an AOM system based on spatial self‐phase modulation and spatial cross‐phase modulation methods is proposed using 2D GDYO NSs. The results reveal that 2D GDYO exhibits tunable nonlinearity and high stability, which is desirable for designing the AOM system. Because of the excellent optical properties of 2D GDYO, a large MD of >98% is achieved for the proposed AOM with a low power of pump light, which is higher than most AOMs currently reported. Thus, GDYO is an excellent modulation material in AOM, which improves the application prospects of carbon nanomaterials in all‐optical devices.

On-chip all-optical quantizer based on the cross polarization modulation effect in a double-ridge a-Si:H-Si3N4 waveguide.

The on-chip all-optical quantizer is a key functional module to realize all-optical analog-to-digital conversion. It has important applications in future optical communication and ultrafast all-optical signal processing systems. To the best of our knowledge, a novel all-optical quantization scheme based on the cross-polarization modulation effect in a double-ridge a-Si:H-Si3N4 waveguide is proposed. For the optimized waveguide, the maximum nonlinear coefficient and transmission loss at the probe wavelength are 2680.5m-1W-1 and 2.246 dB/cm, respectively. The simulation results of the proposed all-optical quantizer show that a nonlinear phase shift of 8 can be generated in the 8.79 mm long waveguide when the peak pump light power is 0.8 W. A 16-level quantization and a 4-bit quantization resolution are obtained. The effective number of bits is 3.79-bit, which is only 0.21-bit away from the ideal resolution.

Performance characterization of a self-made terahertz photoconductive antenna.

A terahertz (THz) photoconductive antenna is prepared using, to the best of our knowledge, a novel method, which has high yield and strong stability. It eliminates the stripping process of a thin-film THz antenna and effectively prevents the toxicity of the corrosion solution, the easy damage in the transfer process, and the weak bonding with the substrate. First, a 200 µm copper wire is bundled on a low-temperature GaAs epitaxial wafer, and then the electrode of the photoconductive antenna is fabricated using the vacuum evaporation method. Finally, the THz time-domain signal with a high signal-to-noise ratio and good repeatability is obtained using an 800 nm laser. Additionally, the influence of pump light and detection light power on THz signal intensity is studied when the total optical power is unchanged. Results show that when the total power of the laser is greater than a certain value, there is an optimal ratio between the pump power and the detection power, which can maximize the signal-to-noise ratio of the THz wave. This provides a basis for the effective application of a THz antenna and lays a foundation for improving the detection sensitivity of samples.

Design and Application of Waveguide Microwave Electron Synthesis Power Amplifier Using Er3+−Yb3+ Co-Doped Nanocrystalline

The solid-state power device has the advantages of small size, light weight and low working voltage, but the output power of the device is limited and cannot meet the engineering needs of power synthesis. Based on the characteristics of erbium (Er3+)-doped optical waveguide amplifier (EDWA), Er3+-ytterbium (YB3+) nanocrystalline were introduced into the design of solid-state power devices, and then nanoelectronic devices were designed to improve the output power of the device. First, NaYF4: 8%Er3+, 16%Yb3+ nanocrystalline were prepared. SU-8 UV glue was used to prepare NaYF4: Er3+. Yb3+ nanocrystalline doped polymer waveguide amplifier was designed and used to observe the waveguide morphology and its performance was tested. Then, the power synthesis amplification technology was studied, and the power distribution-synthesis network based on waveguide E–T junction was designed. The waveguide-microstrip transition structure adopted ridge waveguide transition. On this basis, the 4-stage waveguide E-plane stepped structure was introduced and its structure was simulated. In the design of the power synthesis amplifier, the signal gain of the synthesis amplifier was tested by using the nanocrystal-doped polymer waveguide amplifier as the power unit device. The experimental results show that the output signal light of the nanocrystal-doped polymer waveguide amplifier can be received by an infrared detector. When the pump light power at 980 nm is 200 mW and the signal light power is only 0.1 mW, the maximum relative gain is 4.7 dB in a 1.2 cm long waveguide. The saturated output power of the power unit device is 19.3 dB~19.8 dB, which is close to the saturated output power required by the chip manual. The gain curve of the power synthesis amplifier is relatively flat, that is, the use of nanocrystal-doped polymer waveguide electronic devices effectively improves the synthetic signal gain and reduces the adverse impact of power distribution-synthetic passive network loss.

Gain enhancement of polymer waveguide amplifier based on NaYF4 : Er[formula omitted], Yb[formula omitted] nanocrystals using backward pump scheme

Optical waveguide amplifiers based on NaYF4 : Er3+, Yb3+ nanocrystals prepared by high-temperature thermal decomposition method with forward and backward pump schemes are designed. The gain characteristics of the two schemes are compared through simulation and experiment. For an input signal power of 0.1 mW and a pump power of 270 mW, relative gains of 5 and 5.6 dB are obtained by forward and backward pumping, respectively, in a 9-mm-long waveguide at a wavelength of 1530 nm. Simulation and experimental results show that the gain of backward pumping was higher than that of forward pumping by 12%. The utilization rate of pump light power is greatly improved, which is beneficial to the optimization design of waveguide amplifiers.

High-Performance Graphene-on-Silicon Nitride All-Optical Switch Based on a Mach–Zehnder Interferometer

We propose and experimentally demonstrate a high-performance graphene-on-silicon nitride (Si3N4) all-optical switch based on a Mach-Zehnder interferometer (MZI). In our device, the graphene overlaying on a Si3N4 waveguide absorbs part of the pump light power and generates heat. Then, the Si3N4 waveguide underneath can be heated and its refractive index can be changed due to the thermo-optic effect. In this way, the phase of the probe light in the Si3N4 arm with graphene on top is tuned and all optical switching can then be implemented. In the experimental demonstration, an all-optical switch with a chip size of ~0.36 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is realized with an extinction ratio of 11 dB. The tuning efficiency is measured to be 0.00917 π/mW, which is insensitive to the wavelength of the pump light. All-optical switching is also demonstrated, while the rise and fall time constants are measured to be 571 ns and 1.29 μs, respectively. These results show that our proposed configuration provides a functional integrated component for the development of efficient all-optical control devices with a fast switching speed on the insulator platform. Moreover, by using integrated MZI structure, our design could potentially achieve a broad bandwidth.

Improvement of spin polarization spatial uniformity in optically pumped atomic magnetometers based on counter-propagating pump beams and atomic diffusion

In an optically pumped alkali vapor cell with a high density of atoms, the attenuation of the pump light generates a spatially non-uniform distribution of the electronic spin polarization of alkali atoms, which is detrimental to biomagnetism applications of magnetometers as well as the hyperpolarization of noble gas atoms. Therefore, in this study, we propose a new scheme to generate a nearly uniform, unsaturated spin polarization region based on counter-propagating pump beams and atomic diffusion. A finite element method-based simulation is used to demonstrate the three-dimensional distribution of the spin polarization in a spherical cell. The effects of cell temperature and pump light power on the homogeneity of the spin polarization are studied. The distribution of spin polarization near the center of the cell is experimentally measured and a 1 cm uniform spin polarization region is achieved in the center of the cell. The uniformity of spin polarization in the center region of the cell increased by 50% compared with single beam pumping. The advantage of our proposed scheme is that it can generate an unsaturated uniform region of spin polarization in the center of a cell using a single species of alkali atoms.

Research on second-order Raman fiber amplifier based on particle swarm optimization

In order to further improve the performance index of second-order Raman fiber amplifier, the main parameters of second-order RFA were analyzed. First, a structural model that can be controlled by optical switches and switched between two modes of traditional second-order and traditional first-order RFA is designed. It is proved through simulation that second-order RFA can increase the system gain and improve noise performance. The gain performance of first-order RFA is optimized. The optimization goal is to reduce the flatness. The particle swarm optimization algorithm is used to optimize the configuration of the wavelength and power of the pump light. After further structural improvement, a second-order RFA with a gain of 24.50 dB and a gain flatness of 0.98 dB were achieved in a 100 nm bandwidth. These results provide a reference for the design of second-order RFA with better performance in the future.