- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[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) - 4.37 GHz L-Band Passively Harmonic Mode-Locked Fiber Laser Based on Nonlinear Polarization Rotation
摘要： L-band passively harmonic mode-locked (PHML) fiber lasers are important because various practical applications, such as high-speed optical sampling, dense wavelength division multiplexed (DWDM) systems and material processing, etc. Therefore, L-band PHML fiber lasers have been widely concerned in recent years. In 2012, J. Du et al experimentally achieved L-band PHML pulses by utilizing graphene as a saturable absorber (SA) [1]. Under a certain pumping power, 2nd to 4th harmonic orders can be tuned by adjusting polarization controllers (PCs). In 2014, Y. Meng et al obtained 5.88 GHz L-band PHML pulses with 19 dB super-mode suppression ratio (SMSR) in an Er-Yb co-doped double-clad fiber laser using a graphene SA [2]. In 2018, Q. Huang et al built up a 550 MHz L-band PHML fiber laser based on carbon nanotubes film for the first time [3]. It is worth noting that all of these results are focused on the generation of L-band PHML by utilizing a physical SA. However, the fabrication of physical SA can be complicated with high cost and its thermal damage threshold is not enough to support high pump power which have great impact on the repetition rate of harmonic pulses. Meanwhile, nonlinear polarization rotation as an effective SA have many advantages including high thermal damage threshold, low fabrication cost, high modulation depth and compactness. Therefore, it is desirable to build an L-band PHML fiber laser based on NPR.
关键词： fiber laser,nonlinear polarization rotation,passively harmonic mode-locked,L-band
更新于2025-09-12 10:27:22
-
[IEEE 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - Atlanta, GA, USA (2019.7.7-2019.7.12)] 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting - A 3-D Printed Ka-band Twisted Waveguide Filter with Filtering and Polarization Rotation
摘要： This paper presents a Ka-band twisted bandpass filter integrated with a pair of orthogonally feed waveguides. It can achieve filtering and polarization rotation simultaneously. To validate the presented approach, a 4th order bandpass filter operating at 34 GHz with 2.9% fractional bandwidth is designed and fabricated by a stereolithography-based 3-D printing process. The RF-measured results demonstrate a slight frequency shift of 0.36%, an insertion loss of 0.81 dB, and a return loss better than 15 dB.
关键词： 3D printing,twisted waveguide,polarization rotation,filter
更新于2025-09-12 10:27:22
-
170 mW-level mode-locked Er-doped fiber laser oscillator based on nonlinear polarization rotation
摘要： In our work, by optimizing the length of the cavity and using high-power home-made pump source, based on the commonly-used nonlinear polarization rotation (NPR) technique, we designed a stable all-fiber high-power Er-doped mode-locked laser successfully. The maximum average output power was as high as 174 mW under the pump power of 2659 mW. To our knowledge, 174 mW was a new record average output power of NPR based all-fiber mode-locked Er-doped fiber laser, which was much higher than the results reported previously. Our work will provide a significant reference for future demonstrations of high-power mode-locked Er-doped fiber lasers and promote the applications of mode-locked Er-doped oscillators.
关键词： Er-doped fiber laser,mode-locked,high-power,nonlinear polarization rotation
更新于2025-09-12 10:27:22
-
[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) - Multiple Switchable Generation between Noise-Like Pulse and Dissipative Soliton in an Er-Doped Fiber Laser Based on Nonlinear Polarization Rotation
摘要： In addition to some regular pulses such as conventional soliton (CS) and dissipative soliton (DS), passively mode-locked fiber lasers can also generate another type of distinctive pulse, i.e. the so-called noise-like pulse (NLP) [1]. Generally speaking, in NLP fiber lasers, NLP can be switched from CS or DS by increasing the pump power or adjusting the polarization controller (PC) [2]. However, as far as we know, multiple switchable generation between NLP and DS or CS have never been reported. We here show the multiple switchable phenomenon between NLP and DS from an Er-doped fiber laser (EDFL) based on nonlinear polarization rotation (NPR) for the first time. This kind of fiber laser not only facilitates the deep understanding of the properties and mechanisms of NLP but also paves a new way for the design of multi-functional light source.
关键词： noise-like pulse,dissipative soliton,nonlinear polarization rotation,Er-doped fiber laser,multiple switchable generation
更新于2025-09-11 14:15:04
-
[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) - Temperature Dependence of Magnetic Permeability and Optical Polarization Rotation of Gallium-Terbium Garnet Crystals
摘要： Faraday isolators (IF) are widely used in high-power fiber lasers in order to eliminate the detrimental influence of back reflections during the laser operation. One of the most widespread materials used for IF is a gallium-terbium garnet (TGG) crystal due to its appropriate magneto-optical properties. However, heating of magneto-optical crystals due to absorption of laser radiation deteriorates IF properties. Non-uniform heating leads to mechanical stresses and, therefore, to non-uniform polarization distortions. Values of optical absorption coefficients of TGG greatly depend on a crystal growth technology. Determination of the temperature dependence of optical absorption of TGG crystal was also one of the goals of this research. Optical absorption coefficient of cylindrical TGG sample (diameter d = 0.4 cm, length l = 2 cm) at 1060 nm wavelength was measured using laser calorimetry, i.e. by measuring the temperature of the crystal heated by transmitting laser radiation. Dependence of the crystal heating on transmitted optical power was 1.1±0.1 K/W. Absorption coefficient was calculated by solving the heat balance equation. Its value has increased from 1.6*10-3 cm-1 to 1.9*10-3 cm-1 as a result of heating from 22 oC to 43 oC. Also the contribution of the temperature dependent magnetic permeability μ(T) of TGG on the polarization rotation angle β was experimentally estimated. Temperature dependence of the magnetic permeability of TGG crystal was experimentally measured using resonant impedance spectroscopy. The value of TGG magnetic permeability was about 1.008 at room temperature (20 oC) and has decreased by Δμ = ? 1.2*10-4 when the crystal was heated to 80 oC. The temperature dependences of the polarization axis rotation angle change Δβ were measured in the cases of the uniform heating of TGG sample in a furnace and its nonuniform heating by transmitting linearly polarized laser radiation up to 30 W of optical power (1064 nm wavelength, 2 mm beam diameter). Applied magnetic field strength was 0,4 T, full angle of polarization axis rotation – 17,5 deg. Taking into account the measurement errors Δβ(T) ? (5 ± 0.25)*10-2 deg/ oC for both cases. It should be noticed that narrower laser beams can lead to greater differences due to the presence of larger temperature gradients. Consideration of the measurement results of μ(T) and β(T) revealed that the contribution of magnetic permeability variation with temperature to an overall polarization rotation angle change is almost 90 times lower than the thermally induced change of Verdet constant. Nevertheless, μ(T) influence should be considered if a precise control of polarization axis angle is required.
关键词： gallium-terbium garnet,Faraday isolators,TGG,magnetic permeability,temperature dependence,optical polarization rotation
更新于2025-09-11 14:15:04
-
[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - All-Fiber Passively Mode-Locked Erbium-Doped Fiber Laser Using a Femtosecond Laser Inscribed 45°-Tilted Fiber Grating
摘要： A passively mode-locked fiber laser using femtosecond inscribed plane-by-plane 45°-tilted fiber grating is experimentally demonstrated. The generated solitons center at 1561.8 nm with bandwidth reaching 7.14 nm and pulse width of 1.1 ps.
关键词： fiber Bragg gratings,mode-locked lasers,nonlinear polarization rotation
更新于2025-09-11 14:15:04
-
Scatterer Surface Design for Wave Scattering Application
摘要： In this paper, radio wave scattering is considered and an optimal scatterer surface is realized. For this purpose, an ultra-wideband and high-efficiency polarization converter unit-cell is proposed. Here, the proposed polarization converter unit-cell and its mirror are combined to provide 180? phase difference for scattering purposes. The desired combination of unit-cells which produces uniform scattering pattern and maximum wave attenuation achieved employing group search optimization (GSO) algorithm. For the problem at hand, the GSO optimization algorithm is presented in bi-level format including master and slave levels. Simulation and experimental results showed that the 10 dB bandwidth of normalized RCS reduction is achieved in ultra-wideband ranging from 5.5 GHz to 20.51 GHz with a fractional bandwidth of 115%, assuring a favorable performance of the proposed method. In addition, a wide angle bistatic RCS reduction over a wide frequency band is attained.
关键词： scatterer structure,ultra-wideband,radio-wave scattering,Polarization rotation (PR)
更新于2025-09-10 09:29:36
-
A Wideband, Single-Layer Reflectarray Exploiting A Polarization Rotating Unit Cell
摘要： We present a new technique for designing wideband, single-layer reflectarray antennas. The proposed reflectarray exploits a wideband, polarization rotating unit cell that rotates the polarization of the reflected wave with respect to that of the incident wave by 90?. This unit cell and its mirror image were used as 1-bit spatial phase shifters capable of providing a 0?/180? phase shift over a wide bandwidth of 5.4-12.7 GHz. Using this, a reflectarray antenna with 1-bit phase quantization was designed to operate at X band with aperture dimensions of 28.8 cm × 28.8 cm and a focal length of 30 cm. A prototype of the proposed reflectarray was fabricated and characterized using a spherical near-field measurement system. We determined the antenna’s 3 dB gain bandwidth to be approximately 37.4% with a maximum realized gain of 24.2 dBi. Over its entire band of operation, the polarization purity of the antenna remains better than 13 dB and side-lobe levels of better than 12 dB were achieved.
关键词： periodic structures,Reflectarray antennas,polarization rotation,antenna arrays
更新于2025-09-10 09:29:36