- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Self-wavelength-sweeping in a bi-directional thulium-doped fiber ring laser
摘要： We report for the first time the self-wavelength-sweeping phenomenon of a bi-directional thulium-doped fiber ring laser. The laser wavelength can spontaneously sweep in both lasing directions at a rate up to 0.2 nm s?1 over 15 nm sweeping range in the 1.95 μm wavelength region. The sweeping rate can be controlled by simply changing the state of polarization of the laser cavity. The laser can be tuned to generate a periodical wavelength-swept output with microsecond pulses in the time domain. The sweep rate can also be tuned to zero to give a static lasing wavelength.
关键词： self-wavelength-sweeping,thulium-doped fiber ring laser,polarization control,bi-directional
更新于2025-11-28 14:23:57
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Optical Generation of High-power Terahertz Pulses for Tunable Wave Source
摘要： High-power terahertz pulse generation and its polarization and frequency control by optical rectification with nonlinear organic crystals were studied. Terahertz pulses up to 730 nJ/pulse was generated from a DAST crystal pumped by 250 μJ femotosecond laser pulses with a central wavelength of 1500 nm. The terahertz peak electric field is estimated as 860 kV/cm if we focus the terahertz beam to φ=300 μm spot, which is expected to nonlinear material control application. We proposed the high-power terahertz polarization pulse shaping using the double stacked nonlinear organic crystals excited with tailored pump pulses. Through the terahertz modulation of pump pulses, the waveform shaping of the high-power terahertz pulses are expected, which leads to selective excitation of molecules or spin waves.
关键词： optical rectification,terahertz pulses,nonlinear organic crystals,polarization control,DAST crystal
更新于2025-09-23 15:21:01
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Special Issue: New Horizon of Plasmonics and Metamaterials
摘要： Plasmonics and metamaterials are growing fields that consistently produce new technologies for controlling electromagnetic waves. Many important advances in both fundamental knowledge and practical applications have been achieved in conjunction with a wide range of materials, structures and wavelengths, from the ultraviolet to the microwave regions of the spectrum. In addition to this remarkable progress across many different fields, much of this research shares many of the same underlying principles, and so significant synergy is expected. This Special Issue introduces the recent advances in plasmonics and metamaterials and discusses various applications, while addressing a wide range of topics in order to explore the new horizons emerging for such research.
关键词： metasurfaces,infrared sensors,plasmonics,metamaterials,polarization control
更新于2025-09-23 15:19:57
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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) - Frequency-and-polarization-controllable High-power THz Wave Generation Using Organic Nonlinear Optical Crystal
摘要： Arbitrary control of high-power THz polarization and frequency is studied by the numerical calculation based on the coupled wave approach. THz wave generation using organic crystals via optical rectification provides high conversion efficiency. To overcome the limitation of the generated THz field direction which comes from their optical anisotropy, we propose the synthesis of THz wave generated from two crystals whose optical axis are orthogonal each other. By the calculation, the linearly and circularly polarized THz wave generation by changing the time delay of two pump pulses is demonstrated.
关键词： optical rectification,organic nonlinear optical crystal,polarization control,frequency control,THz wave generation
更新于2025-09-16 10:30:52
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Metasurface-Integrated Photonic Platform for Versatile Free-Space Beam Projection with Polarization Control
摘要： Densely integrated photonic circuits enable scalable, complex processing of optical signals, including modulation, multiplexing, wavelength conversion, and detection. Directly interfacing such integrated circuits to free-space optical modes will enable novel optical functions, such as chip-scale sensing, interchip free-space interconnect and cooling, trapping, and interrogation of atoms. However, doing this within the limits of planar batch fabrication requires new approaches for bridging the large mode scale mismatch. Here, by integrating a dielectric metasurface with an extreme photonic mode converter, we create a versatile nanophotonic platform for efficient coupling to arbitrary-defined free-space radiation of 780 nm wavelength with well-controlled spatially-dependent polarization, phase, and intensity. Without leaving the chip, the high index photonic mode is converted first to a ～ 200 μm wide, precisely collimated, linearly-polarized Gaussian beam, which is then modified by a planar, integrated, low-loss metasurface. We demonstrate high numerical aperture, diffraction limited focusing to an ～ 473 nm spot at an ～ 75 μm working distance, and combine it with simultaneous conversion from linear to elliptical polarization. All device components are lithographically defined and can be batch fabricated, facilitating future chip-scale low-cost hybrid photonic systems for bio-sensing, nonlinear signal processing and atomic quantum sensing, frequency references and memory.
关键词： photonic-free-space coupling,free-space radiation,Integrated photonics,metasurface,high-NA focusing,polarization control
更新于2025-09-12 10:27:22
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Demonstration of polarization control GaN-based micro-cavity lasers using a rigid high-contrast grating reflector
摘要： We reported on Gan microcavity (Mc) lasers combined with one rigid tio2 high-contrast grating (HcG) structure as the output mirror. the HcG structure was directly fabricated on the Gan structure without an airgap. The entire MC structure comprised a bottom dielectric distributed Bragg reflector; a GaN cavity; and a top HCG reflector, which was designed to yield high reflectance for transverse magnetic (tM)- or transverse electric (te)-polarized light. the Mc device revealed an operation threshold of approximately 0.79 MW/cm2 when pulsed optical pumping was conducted using the HcG structure at room temperature. The laser emission was TM polarized with a degree of polarization of 99.2% and had a small divergence angle of 14° (full width at half maximum). This laser operation demonstration for the Gan-based Mc structure employing an HcG exhibited the advantages of HcGs in semiconductor lasers at wavelengths from green to ultraviolet.
关键词： Gan microcavity lasers,high-contrast grating reflector,GaN,polarization control,TiO2
更新于2025-09-11 14:15:04
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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) - Complex-Birefringent and Chiral Waveplates with Metasurfaces
摘要： Metasurfaces composed of arrays of nano-resonators are a powerful tool for manipulation of polarization of light. All-dielectric metasurfaces do not suffer absorption losses and are highly transparent in contrast to metallic structures, and combined with recent advances in their design and fabrication, have enabled efficient polarization manipulation and arbitrary phase shaping. A new regime of complex-valued birefringence has been recently suggested, extending the notion of real-valued birefringence through the specially introduced polarization-sensitive loss or gain. This can enable fundamentally new possibilities for polarization control, such as amplifying the angle between polarization vectors to improve detection sensitivity. However, a practical realization of complex-valued birefringence concept was missing. In particular, the theoretical approach in Ref. [4] was based on a complicated metamaterial with loss and gain, which is challenging to fabricate and not suitable for quantum applications. Here, we report on a new conceptual approach for implementing arbitrary complex-valued birefringence with pairwise birefringent elements using high-index dielectric nanostructures. We formulate a practical design principle, which is optimal for achieving any desirable polarization transformation. While loss is inherently necessary for implementing complex birefringence, our all-dielectric metasurface design achieves the mathematically minimum required amount of loss through tailored diffraction without any material absorption.
关键词： metasurfaces,birefringence,polarization control,dielectric nanostructures
更新于2025-09-11 14:15:04
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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) - Interferometric Attosecond Lock-in Measurement of Extreme Ultraviolet Circular Diehroism
摘要： Probing vectorial properties of light-matter interactions requires control over the polarization state of light. The generation of extreme-ultraviolet (XUV) attosecond pulses opened new perspectives in measurements of chiral phenomena. Recently, new methods for polarization control in the XUV range, which are based on manipulation of the high harmonic generation (HHG) process were demonstrated [1-4]. However, the limited polarization control in this regime prevents the development of advanced measurement schemes for weak vectorial signals, which require polarization modulation. In our work [5], we establish an XUV lock-in detection scheme, allowing the isolation and amplification of extremely weak chiral signals, by achieving a dynamical control over the polarization state of the XUV light. We demonstrate a time-domain approach to control and modulate the polarization state. This scheme enables us to characterize the polarization state via an in-situ measurement (see Figure 1a,d,e). Our approach, resembling a birefringent crystal for the visible range, is based on the collinear superposition of two independent, phase-locked, orthogonally polarized XUV sources and the control of their relative delay with sub-cycle accuracy (see Figure 1b). We achieve lock-in detection of XUV magnetic circular dichroism (XMCD) in cobalt, transferring weak amplitude variations into a phase modulation (see Figure 1c), by controlling the relative angle, θ , between the two linearly polarized sources. This approach holds the potential of significantly extending the scope of vectorial measurements to the attosecond and nanometer frontiers.
关键词： attosecond pulses,polarization control,high harmonic generation,extreme-ultraviolet,chiral signals,XUV magnetic circular dichroism,XUV lock-in detection
更新于2025-09-11 14:15:04
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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) - Compact Femtosecond Laser Direct Written Integrated Retarders Based on Embedded Nanogratings
摘要： Femtosecond Laser Direct Writing (FLDW) is a well-known rapid prototyping method to fabricate integrated optical circuits in glass chips. These circuits have been used to show various quantum information applications, using the states of photons as qubits. Generally, when transmitting information via single photons, it is desirable to make use of all possible degrees of freedom that this photon has to offer, in order to increase the amount of information transferred per photon. One of these degrees of freedom is the photon’s polarization. To make use of this degree of freedom, devices capable of manipulating the polarization are required. Various approaches for manipulating the polarization of photons in a FLDW circuit have been demonstrated before, of which some were used for quantum information applications. In our work, we present a novel method of polarization control using embedded nanogratings as waveplates. These nanogratings are highly birefringent self-assembled structures. Due to their relatively high form birefringence on the order of Δn = 10^-3, they can be used as a compact waveplate enabling further miniaturization of integrated optical circuits. The properties of these gratings can be altered by using different laser parameters during the inscription process. We have added various waveplates made of nanogratings into FLDW waveguides. We demonstrate their functionality as waveplates of different retardation and optical axis orientations using crossed polarizer birefringence measurements. Due to the chosen writing geometry, a full control over the direction of the optical axis can be achieved. The thickness of these structures is on the order of a few hundred micrometers. Former approaches for polarization control in FLDW circuits required structures in the range of millimetres to centimeters. Some of these approaches were limited in the achievable optical axis orientations. Our waveplates can be both used for classical applications and as single qubit quantum gates, which will be demonstrated. Waveplate structures usable as Hadamard, Pauli-x, Pauli-z and Pi/8th gates have been fabricated. The transferability to fibers will be discussed.
关键词： integrated optical circuits,polarization control,quantum information applications,waveplates,nanogratings,Femtosecond Laser Direct Writing
更新于2025-09-11 14:15:04
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Evolution of degree of polarization of partially coherent beams propagation in slant and horizontal atmospheric turbulence
摘要： In this paper, the analytical expressions for the degree of polarization (DoP) of the electromagnetic Gaussian Schell-model (GSM) beam propagating along a slant path in atmospheric turbulence are obtained. The expressions are used to analyze factors such as the waist radius, amplitude ratio, wavelength, and refractive-index structure constant of the polarization properties of the GSM beam, and we come to some new conclusions. The main results that when the components of the waist radius are equal (rx = ry), there is a waist radius within 2 cm \ rx \ 4 cm that can provide the most concentrated DoP distribution, and the axis point DoP will eventually approach the initial value as the transmission distance increases, implying that it exhibits self-recovering characteristics. In addition, compared to a horizontal path, the DoP distribution of the GSM beam propagating along a slant path is more concentrated, and the propagation distance corresponding to the maximum axis point DoP is longer. Therefore, when the GSM beam propagates along a slant path, the detector can receive information at longer distances. The research results provide a theoretical support for the control of the polarization state of local beam in coherent optical communication systems.
关键词： Coherent optical communication systems,Polarization control,Atmospheric turbulence
更新于2025-09-10 09:29:36