Name: experimental methods for spin- and angle-resolved photoemission spectroscopy combined with polarization-variable laser
Uploaded: 2018-06-28T13:00:00.000+00:00
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Description: Watch this Scientific Journal Video about Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser at JoVE.com

M. 나카야마, S. Toyohisa, A. 후쿠시마 감사 하 고 대 한 영 이시다 실험적인 체제를 지원 합니다. 우리는 기꺼이 자금 JSP Grantin-원조에서 프로젝트 번호 26287061를 통해 과학적 연구 (B)를 위한 대 한 젊은 과학자 (B) 프로젝트 번호를 통해 인정 15 K 17675. 이 작품 또한 일본의 문 부 과학성 (혁신적인 지역 "토폴로지 재료 과학," 부여 번호 16 H 00979) 및 JSP KAKENHI (보조금 번호 16 H 02209)에 의해 지원 되었다

1. 샘플 마운트 및 설치
<ol><li>1 × 1 × 0.5 m m의 대략적인 크기에 Bi2Se313 의 단일 크리스탈 샘플을 잘라 샘플 홀더를 샘플을 접착제로,3 , 사용 은색 기반 에폭시.</li>
	<li>샘플 표면에 스카치 테이프를 붙여 넣습니다. 참고: 스카치 테이프는 원자적 깨끗 한 표면을 얻기 위해 초고 진공 (UHV) 챔버에 샘플을 쪼개 사용 됩니다.</li>
	<li>로드 잠금에 잡지 샘플으로 샘플을 설치 하 고 로드 자물쇠의 압력은 1 × 10-5 아빠 보다 낮은 될 때까지 펌프를 시작</li>
</ol>2. 샘플 고착
<ol><li>로드 잠금 및 UHV 준비 챔버 사이 UHV 밸브를 엽니다.</li>
	<li>로드 잠금 챔버에 연결 되어 있는 선형/회전 피드스루를 사용 하 여 부하 바위 준비 약 실에 샘플 잡지를 이동 합니다.</li>
	<li>준비 실에 연결 하는 전송 막대에 의해 잡지 샘플에서 샘플을 선택 합니다.</li>
	<li>다시 넣어 샘플 잡지 로드 잠금 고 UHV 밸브를 닫습니다.</li>
	<li>준비 챔버의 압력 아래 5 × 10-7 아빠 될 때까지 기다립니다</li>
	<li>준비 실에서 동요 막대기를 사용 하 여 스카치 테이프를 껍질 하 고 쪼개 UHV 조건 샘플.</li>
</ol>3. 샘플 측정 위치로 전송
<ol><li>UHV 측정 챔버에 샘플을 전송 하 고 측정 챔버 장착 나사 드라이버에 의해 주요 gonio 단계를 샘플을 수정.</li>
	<li>측정 위치에 gonio 단계를 이동 하 고 마이크로미터 단계를 사용 하 여 정확 하 게는 분석기의 초점에 샘플 위치 이동.</li>
</ol>4. 7 eV-레이저 설치
<ol><li>Nd:YVO4 레이저를 켭니다. 참고: 레이저 120 MHz의 높은 반복 속도 355 nm 레이저 빛을 생성합니다.</li>
	<li>레이저 빔 셔터를 열고 레이저 KBBF 크리스털 및 177의 2 차 고조파 웨이브 통과 확인 nm (6.994 eV) 생성 됩니다.</li>
	<li>가변 감쇠기와 355 nm 레이저의 파워를 변경 하 여 7 eV-레이저의 파워를 최적화 합니다.</li>
</ol>5. ARPES 데이터 수집
<ol><li>데스크톱 컴퓨터에서 분석기 제어 소프트웨어를 엽니다. 참고: 우리는 전자 편향 제어 ScientaOmicron 분석기에 대 한 일반적인 프로그램은 "SES 소프트웨어"를 사용 합니다.</li>
	<li>설치메뉴에서 시퀀스 아래...를 선택 합니다 (그림 2, i.2-1 단계) 바.</li>
	<li>광전자 편향 된 페르미 표면 매핑을 수행 하 ARPES 구성 (그림 3, i.3-1 단계) 및 ARPES 매핑 목록 (그림 3, i.3-2 단계)에서 선택 합니다.</li>
	<li>(그림 3, i.3-3 단계)를 편집 을 클릭 하 고 0.5 ° (그림 3, i.3-4 단계)의 단계 크기는 방출 각도 θy 의 12 °-12 °에서 배열 하는 페르미 표면 매핑 구성. 참고: 전자 편향 된 반구형 분석기 샘플 회전 없이 페르미 표면 매핑할 수 있습니다.</li>
	<li>(그림 2, i.2-3 단계)을 실행 을 클릭 합니다.</li>
</ol>6. SARPES 데이터 수집
<ol><li>수동으로 SARPES 측정 분석기 입구 슬릿과 조리개 크기 (그림 1)를 포함 하 여 시스템 설정 변경.</li>
	<li>설치메뉴에서 시퀀스 아래...를 선택 합니다 (그림 2, i.2-2 단계) 바.</li>
	<li>목록 (그림 4, i.4-2 단계)에서 회전 구성 (그림 4, i.4-1 단계)와 정상 을 선택 하 고 확인 (그림 4, 단계 i.4-3)을 클릭 합니다.</li>
	<li>메뉴 모음 및 컨트롤 세타 DA30 (그림 5, i.5-1 단계)을 선택... (그림 5, i.5-2 단계) DA30 각도 (θx, θy) 구성에 대 한 설정 패널을 엽니다.</li>
	<li>선택 방출 각도 (θxθy) SARPES 스펙트럼 (그림 5, 단계 i.5-3)을 (-6 °, 0 °) =.</li>
	<li>VLEED 대상 특정 축 따라 양의 방향에 자력을 띠게 하 바이 폴라 콘덴서 뱅크를 제어 하 여 자기장을 적용 (α: x, y또는 z). 참고: 시스템에서이 프로세스는 명령 프롬프트 [그림 6 (a)]를 통해 할 수 있습니다.</li>
	<li>강도 스펙트럼 (그림 2, i.2-3 단계)을 실행 을 클릭 합니다.</li>
	<li>Α에 따라 음의 방향에서 VLEED 대상 끌다 강도 스펙트럼을 스캔을 시작 하는 자기장을 적용 합니다.</li>
	<li>스핀-분극 및 스핀 해결 스펙트럼을 계산 합니다.</li>
</ol>7. 스캔 빛 분극 의존
<ol><li>λ/2-파장판 정확 하 게 조정 7 eV-레이저의 빛 분극 스테핑 모터에 의해 제어의 각도 변경 합니다. 참고: 시스템에서이 프로세스는 명령 프롬프트 [그림 6 (b)]를 통해 할 수 있습니다.</li>
	<li>X, y 및 z 축에 대 한 스핀 해결 스펙트럼을 가져가 라.</li>
	<li>3 °의 단계 크기 102 °에 0 °에서 절반 파장판 각도 변화 빛 분극의 기능으로 스핀 해결 스펙트럼을 검사 합니다.</li>
</ol>

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저자 들은 아무 경쟁 금융 관심사 선언 합니다.

ARPES 및 SARPES 기술 전자 밴드 구조 스핀-검색1,2및 밴드 매핑을 통해 공부에 대 한 일반적으로 사용 되었습니다. 이러한 일반적인 장점 위에 표시 된, 뿐만 아니라 레이저-SARPES 광 쌍 극 자 여기에 궤도 선택 규칙에 따라 시각화 하는 wavefunction 및 양자 스핀 간섭에 스핀-궤도 결합 효과 대 한 새로운 기술로 채택 될 수 있다 . 레이저의 편광 waveplates p-...

고체 상태1에 quasiparticle 밴드 구조를 조사 하는 가장 강력한 도구 중 하나에 각도 해결 광전자 방출 분광학 (ARPES) 기술을 개발 했다. ARPES의 매력적인 특징의 대부분은 에너지와 운동량 공간에서 전자 상태 특성 밴드 매핑 위한 기능입니다. 스핀 해결 ARPES (SARPES), 여기 스핀-감지기, 예를 갖추고 있습니다. 더 모트 탐지기2,3, 관찰된 밴드 구조4의 스핀 문자를 해결 하기 위해 수 있습니다. 모트 검출기는 두 개의 축 (x 와 z또는 y 및 z)와 스핀을 측정할 수 있습니다., 더 두 모트 감지기의 조합을 하나의 3 차원4,5의 스핀 방향을 얻을 수 있습니다. . 그러나 십년 동안,, SARPES 실험은 그들의 낮은 효율 (일반적으로 1/10000 스핀 통합 ARPES 측정에 비해)에서 고통을 했다3,,45,6 ,7, 에너지와 각도 해상도 제한 했다. 최근, SARPES의 에너지 분해능 exchange 산란, 소위 매우 낮은 에너지 전자 회절 (VLEED) 검출기7,8,9에 따라 높은 효율적인 회전 검출기로 증가 되었습니다. ,10. 이 검출기, 데이터 품질을 크게 향상 되었습니다와 데이터 수집 시간이 단축 되었습니다. 최근, SARPES 스핀 편광 전자 상태 및 특히 스핀-궤도 결합 효과 표면 밴드7의 회전 질감에 결과 해결 하기 위해 크게 성공 했습니다.
여기, 우리 SARPES 고용 양극 화 변수 진공 자외선 측정 레이저 광 (레이저-SARPES)와 입증이 결합 된 기술의 큰 장점. Bi2Se3스핀-궤도 결합 표면 상태에 조사를 통해 우리는 레이저 SARPES의 두 가지 기능을 제시. 첫째, 쌍 극 자 전이 정권, p-, s에 선형 편광 된 레이저의 궤도 선택 규칙 때문-편광된 빛 선택적으로 다른 궤도 대칭 아이겐 wavefunctions의 부분을 자극. 이러한 궤도 선택적 여기는 그로 인하여 SARPES, 즉, 궤도 선택적 SARPES. 둘째, SARPES에서 3 차원 (3D) 스핀-탐지 스핀 양자 축 방향을 표시 하 고 직접 빛 분극 의존의 전체 정보를 표시 합니다. 이 프로토콜에 우리는 잠시이 최신의 레이저-SARPES 기술을 강한 스핀-궤도 결합 효과 연구를 수행 하는 방법을 설명 합니다.
우리의 레이저-SARPES 시스템은 고체 상태 물리학, 도쿄 대학11을 위한 연구소. 우리의 레이저 SAPRES 기계의 도식 적인 그림은 그림 1에 표시 됩니다. 분극 변수 7 eV 레이저 빛12 샘플 표면 조명 하 고는 photoelectrons 샘플에서 방출 된다. 레이저의 편광 자동으로 MgF2-기반으로 λ/2-와 λ/4-waveplates 선택 사용 하 여 선형 및 원형 분극에 의해 제어 됩니다. 반구형 전자 분석기는 photoelectrons를 해결 하 고 그들의 운동 에너지 (E친척) 및 방출 각도 (θx θy)을 분석 합니다. 광전자 농도 E킨-CCD 카메라에 의해 감시 하는θx 화면에 매핑됩니다. 이 이미지 직접 상호 공간에서 에너지 밴드 구조에 변형 된다.
SARPES 측정을 위해 특정 방출 각도와 운동 에너지는 전자 분석기에 의해 분석 photoelectrons 90도 광전자 디플렉터와 두 개의 VLEED 형 스핀 감지기를 유도 하 고 광전자 빔 2에 초점을 맞추고 있다 Fe(001)-p(1 × 1) 영화 산소에 의해 종료의 다른 목표 대상에 의해 반영 photoelectrons 각 회전 검출기에 배치 하는 channeltron를 사용 하 여 단일 채널 검색에서 검색 됩니다. VLEED 목표는 서로 관하여 직각 형상으로 배열 되는 헬름홀츠 형 전기 코일으로 자성 수 있습니다. 자화 방향 바이 폴라 콘덴서 뱅크에 의해 제어 됩니다. 이중 VLEED 회전 검출기 함으로써 3 차원에 광전자의 스핀 분극 벡터 분석을 사용 합니다.

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experimental methods for spin- and angle-resolved photoemission spectroscopy combined with polarization-variable laser

이 프로토콜의 목표 회전 및 각도 해결 광전자 방출 분광학 분극 변수 7 eV 레이저 (레이저-SARPES)와 함께 수행 하는 방법을 제시 하 고 고체 물리학을 공부에 대 한이 기술의 힘을 보여주는 것입니다. 레이저 SARPES는 두 개의 큰 기능을 달성 한다. 첫째, 선형 편광 된 레이저의 궤도 선택 규칙을 검사 하 여 궤도 선택적 여기 수 실시 SAPRES 실험. 둘째, 기술은 빛 분극의 기능으로 스핀 양자 축 변형의 전체 정보를 표시할 수 있습니다. 레이저 SARPES에서 이러한 기능의 협업의 힘을 보여, 우리는 Bi2Se3의 표면 상태를 스핀-궤도 결합의 수사를 위해이 기술을 적용. 이 기술은 스핀-궤도 결합 wavefunctions에서 스핀과 궤도 구성 요소 분해을 준다. 또한, 직접 스핀 탐지를 사용 하 여의 대표적인 장점은 편광 변수 레이저와 함께 collaborated, 기술은 스핀 양자 축 3 차원에서의 빛 분극 의존 명확 하 게 시각화. 레이저 SARPES는 극적으로 광전자 방출 기술의 능력을 증가 시킵니다.

SARPES 실험을 시작 하기 전에 k 위치 높은 통계 스핀 통합 ARPES 결과와 높은 에너지-각도-해상도 (프로토콜 5.1-5.5)을 사용 하 여 스핀 해결 스펙트럼을 주셔서 정확 하 게 결정 해야 합니다. 이 Bi2Se3 단 결정에 대 한 ARPES 결과 제시는 그림 7 에서 설명 했다. 이 소재는 표면 상태 스핀 편광14,15...

Watch this Scientific Journal Video about Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser at JoVE.com

Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser

여기, 우리 기술로 회전 및 각도 해결 광전자 방출 고체 상태에서 스핀-궤도 결합 효과 시각화 하 분극 변수 7 eV 레이저를 결합 한다.

분극 변수 레이저와 함께 회전 및 각도 해결 광전자 방출 분광학 실험 방법

The goal of this protocol is to present how to perform spin- and angle-resolved photoemission spectroscopy combined with polarization-variable 7-eV laser ...

experimental-methods-for-spin-angle-resolved-photoemission

Research

JoVE Journal

Engineering

9.8K 조회수.  University of Tokyo. 여기, 우리 기술로 회전 및 각도 해결 광전자 방출 고체 상태에서 스핀-궤도 결합 효과 시각화 하 분극 변수 7 eV 레이저를 결합 한다.

비디오: Experimental Methods for Spin- and Angle-Resolved Photoemission Spectroscopy Combined with Polarization-Variable Laser

Angle-resolved Photoemission Spectroscopy At Ultra-low Temperatures

The physical properties of a material are defined by its electronic structure. Electrons in solids are characterized by energy (&omega;) and momentum (k) and the probability to find them in a particular state with given &omega; and k is described by the spectral function A(k, &omega;). This function can be directly measured in an experiment based on the well-known photoelectric effect, for the explanation of which Albert Einstein received the Nobel Prize back in 1921. In the photoelectric effect the light shone on a surface ejects electrons from the material. According to Einstein, energy conservation allows one to determine the energy of an electron inside the sample, provided the energy of the light photon and kinetic energy of the outgoing photoelectron are known. Momentum conservation makes it also possible to estimate k relating it to the momentum of the photoelectron by measuring the angle at which the photoelectron left the surface. The modern version of this technique is called Angle-Resolved Photoemission Spectroscopy (ARPES) and exploits both conservation laws in order to determine the electronic structure, i.e. energy and momentum of electrons inside the solid. In order to resolve the details crucial for understanding the topical problems of condensed matter physics, three quantities need to be minimized: uncertainty* in photon energy, uncertainty in kinetic energy of photoelectrons and temperature of the sample.
In our approach we combine three recent achievements in the field of synchrotron radiation, surface science and cryogenics. We use synchrotron radiation with tunable photon energy contributing an uncertainty of the order of 1 meV, an electron energy analyzer which detects the kinetic energies with a precision of the order of 1 meV and a He3 cryostat which allows us to keep the temperature of the sample below 1 K. We discuss the exemplary results obtained on single crystals of Sr2RuO4 and some other materials. The electronic structure of this material can be determined with an unprecedented clarity.

The overall goal of this method is to determine the low-energy electronic structure of solids at ultra-low temperatures using Angle-Resolved Photoemission Spectroscopy with synchrotron radiation.

울트라 낮은 온도에서 각도 - 해결 Photoemission 분광법

The physical properties of a material are defined by its  electronic structure. Electrons in solids are characterized by energy (&omega;)  and momentum ...

연구

공학

Automation of Mode Locking in a Nonlinear Polarization Rotation Fiber Laser through Output Polarization Measurements

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a new and inexpensive procedure to force mode locking in a pre-adjusted nonlinear polarization rotation fiber laser. This procedure is based on the detection of a sudden change in the output polarization state when mode locking occurs. This change is used to command the alignment of the intra-cavity polarization controller in order to find mode-locking conditions. More specifically, the value of the first Stokes parameter varies when the angle of the polarization controller is swept and, moreover, it undergoes an abrupt variation when the laser enters the mode-locked state. Monitoring this abrupt variation provides a practical easy-to-detect signal that can be used to command the alignment of the polarization controller and drive the laser towards mode locking. This monitoring is achieved by feeding a small portion of the signal to a polarization analyzer measuring the first Stokes parameter. A sudden change in the read out of this parameter from the analyzer will occur when the laser enters the mode-locked state. At this moment, the required angle of the polarization controller is kept fixed. The alignment is completed. This procedure provides an alternate way to existing automating procedures that use equipment such as an optical spectrum analyzer, an RF spectrum analyzer, a photodiode connected to an electronic pulse-counter or a nonlinear detecting scheme based on two-photon absorption or second harmonic generation. It is suitable for lasers mode locked by nonlinear polarization rotation. It is relatively easy to implement, it requires inexpensive means, especially at a wavelength of 1550 nm, and it lowers the production and operation costs incurred in comparison to the above-mentioned techniques.

A protocol to detect and automate mode locking in a pre-adjusted nonlinear polarization rotation fiber laser is presented. The detection of a sudden change in the output polarization state when mode locking occurs is used to command the alignment of an intra-cavity polarization controller in order to find mode-locking conditions.

출력 편광 측정을 통해 비선형 편광 회전 광섬유 레이저의 모드 잠금의 자동화

When a laser is mode-locked, it emits a train of ultra-short pulses at a repetition rate determined by the laser cavity length. This article outlines a ...

High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy

High resolution optical spectroscopy methods are demanding in terms of either technology, equipment, complexity, time or a combination of these. Here we demonstrate an optical spectroscopy method that is capable of resolving spectral features beyond that of the spin fine structure and homogeneous linewidth of single quantum dots (QDs) using a standard, easy-to-use spectrometer setup. This method incorporates both laser and photoluminescence spectroscopy, combining the advantage of laser line-width limited resolution with multi-channel photoluminescence detection. Such a scheme allows for considerable improvement of resolution over that of a common single-stage spectrometer. The method uses phonons to assist in the measurement of the photoluminescence of a single quantum dot after resonant excitation of its ground state transition. The phonon&#39;s energy difference allows one to separate and filter out the laser light exciting the quantum dot. An advantageous feature of this method is its straight forward integration into standard spectroscopy setups, which are accessible to most researchers.

The manuscript describes a method of phonon-assisted quasi-resonant fluorescence spectroscopy that incorporates both laser-limited resolution and photoluminescence (PL) spectroscopy. This method utilizes optical phonons to provide linewidth-limited resolution spectra of atom-like semiconductor structures in the energy domain. The method is also easily realized with a single spectrometer optical spectroscopy setup.

높은 해상도 포논 도움을 준 공명 형광 분광학

High resolution optical spectroscopy methods are demanding in terms of either technology, equipment, complexity, time or a combination of these. Here we ...

Direct Imaging of Laser-driven Ultrafast Molecular Rotation

We present a method for visualizing laser-induced, ultrafast molecular rotational wave packet dynamics. We have developed a new 2-dimensional Coulomb explosion imaging setup in which a hitherto-impractical camera angle is realized. In our imaging technique, diatomic molecules are irradiated with a circularly polarized strong laser pulse. The ejected atomic ions are accelerated perpendicularly to the laser propagation. The ions lying in the laser polarization plane are selected through the use of a mechanical slit and imaged with a high-throughput, 2-dimensional detector installed parallel to the polarization plane. Because a circularly polarized (isotropic) Coulomb exploding pulse is used, the observed angular distribution of the ejected ions directly corresponds to the squared rotational wave function at the time of the pulse irradiation. To create a real-time movie of molecular rotation, the present imaging technique is combined with a femtosecond pump-probe optical setup in which the pump pulses create unidirectionally rotating molecular ensembles. Due to the high image throughput of our detection system, the pump-probe experimental condition can be easily optimized by monitoring a real-time snapshot. As a result, the quality of the observed movie is sufficiently high for visualizing the detailed wave nature of motion. We also note that the present technique can be implemented in existing standard ion imaging setups, offering a new camera angle or viewpoint for the molecular systems without the need for extensive modification.

We present a protocol for creating a real-time movie of a molecular rotational wave packet using a high-resolution Coulomb explosion imaging setup.

레이저 기반 초고속 분자 회전의 직접 이미징

We present a method for visualizing laser-induced, ultrafast molecular rotational wave packet dynamics. We have developed a new 2-dimensional Coulomb ...

화학

Determination of the Excitation and Coupling Rates Between Light Emitters and Surface Plasmon Polaritons

We have developed a unique method to measure the excitation and coupling rates between the light emitters and surface plasmon polaritons (SPPs) arising from metallic periodic arrays without involving time-resolved techniques. We have formulated the rates by quantities that can be measured by simple optical measurements. The instrumentation based on angle- and polarization-resolved reflectivity and photoluminescence spectroscopy will be described in detail here. Our approach is intriguing due to its simplicity, which requires routine optics and several mechanical stages, and thus is highly affordable to most of the research laboratories.

This protocol describes the instrumentation for determining the excitation and coupling rates between light emitters and Bloch-like surface plasmon polaritons arising from periodic arrays.

여기 및 빛 방출 및 표면 플라스몬 Polaritons 사이 요금 커플링

We have developed a unique method to measure the excitation and coupling rates between the light emitters and surface plasmon polaritons (SPPs) arising ...

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F&#8722;

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound electrons with neutral molecules/atoms. State-of-the-art in vacuo anion generation techniques allow application to a broad range of atomic, molecular, and cluster anion systems. These are separated and selected using time-of-flight mass spectrometry. Electrons are removed by linearly polarized photons (photo detachment) using table-top laser sources which provide ready access to excitation energies from the infra-red to the near ultraviolet. Detecting the photoelectrons with a velocity mapped imaging lens and position sensitive detector means that, in principle, every photoelectron reaches the detector and the detection efficiency is uniform for all kinetic energies. Photoelectron spectra extracted from the images via mathematical reconstruction using an inverse Abel transformation reveal details of the anion internal energy state distribution and the resultant neutral energy states. At low electron kinetic energy, typical resolution is sufficient to reveal energy level differences on the order of a few millielectron-volts, i.e., different vibrational levels for molecular species or spin-orbit splitting in atoms. Photoelectron angular distributions extracted from the inverse Abel transformation represent the signatures of the bound electron orbital, allowing more detailed probing of electronic structure. The spectra and angular distributions also encode details of the interactions between the outgoing electron and the residual neutral species subsequent to excitation. The technique is illustrated by the application to an atomic anion (F&#8722;), but it can also be applied to the measurement of molecular anion spectroscopy, the study of low lying anion resonances (as an alternative to scattering experiments) and femtosecond (fs) time resolved studies of the dynamic evolution of anions.

Here, we present a protocol for photoelectron imaging of anionic species. Anions generated in vacuo and separated by mass spectrometry are probed using velocity mapped photoelectron imaging, providing details of anion and neutral energy levels, anion and neutral structure and the nature of the anion electronic state.

F− 의 310 Nm 분리에 의해 설명 하는 음이온의 광전자 이미징

Anion photoelectron imaging is a very efficient method for the study of energy states of bound negative ions, neutral species and interactions of unbound ...

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference

We present a high-performance source of unconditional polarization-entangled photons that have a high-emission rate, a broadband distribution, are degenerated and postselection free. The property of the source is based on the multiple quantum interference effect with a round-trip configuration of a Sagnac interferometer. The quantum interference effects make it possible to use the high generation efficiency of the polarization-entangled photons to process parametric down-conversion, and separate degenerated photon pairs into different optical modes without a postselection requirement. The principle of the optical system was described and experimentally used to measure the fidelity and Bell parameters, and also to characterize the generated polarization-entangled photons from a minimum of six combinations of polarization correlated data. The experimentally obtained fidelity and Bell parameters exceeded the classical local correlation limit and are clear evidence of the generation of unconditional polarization-entangled photons.

We describe an optical system for the generation of unconditional polarization-entangled photons based on multiple quantum interference effects with a detection scheme to estimate the experimental fidelity of generated entangled photons.

다중 양자 간섭을 기반으로 무조건 편광 얽힌 광자를 생성하기 위한 포토닉 시스템

We present a high-performance source of unconditional polarization-entangled photons that have a high-emission rate, a broadband distribution, are ...

Spectral and Angle-Resolved Magneto-Optical Characterization of Photonic Nanostructures

Photonic crystals are periodic nanostructures that can support a variety of confined electromagnetic modes. Such confined modes are usually accompanied by local enhancement of electric field intensity that strengthens light-matter interactions, enabling applications such as surface-enhanced Raman scattering (SERS) and surface plasmon enhanced sensing. In the presence of magneto-optically active materials, the local field enhancement gives rise to anomalous magneto-optical activity. Typically, the confined modes of a given photonic crystal depend strongly on the wavelength and incidence angle of the incident electromagnetic radiation. Thus, spectral and angular-resolved measurements are needed to fully identify them as well as to establish their relationship with the magneto-optical activity of the crystal. In this article, we describe how to use a Fourier-plane (back focal plane) microscope to characterize magneto-optically active samples. As a model system, here we use a plasmonic grating built out of magneto-optically active Au/Co/Au multilayer. In the experiments, we apply a magnetic field on the grating in situ and measure its reciprocal space response, obtaining the magneto-optical response of the grating over a range of wavelengths and incident angles. This information enables us to build a complete map of the plasmonic band structure of the grating and the angle and wavelength dependent magneto-optical activity. These two images allow us to pinpoint the effect that the plasmon resonances have on the magneto-optical response of the grating. The relatively small magnitude of magneto-optical effects requires a careful treatment of the acquired optical signals. To this end, an image processing protocol for obtaining magneto-optical response from the acquired raw data is laid out.

Photonic band structure enables understanding how confined electromagnetic modes propagate within a photonic crystal. In photonic crystals that incorporate magnetic elements, such confined and resonant optical modes are accompanied by enhanced and modified magneto-optical activity. We describe a measurement procedure to extract the magneto-optical band structure by Fourier space microscopy.

광나노구조체의 스펙트럼 및 각도 해결 된 자기 광학 특성 분석

Photonic crystals are periodic nanostructures that can support a variety of confined electromagnetic modes. Such confined modes are usually accompanied by ...

In Situ Measurement of Vacuum Window Birefringence using 25Mg+ Fluorescence

Accurate control of the polarization states of laser light is important in precision measurement experiments. In experiments involving the use of a vacuum environment, the stress-induced birefringence effect of the vacuum windows will affect the polarization states of laser light inside the vacuum system, and it is very difficult to measure and optimize the polarization states of the laser light in situ. The purpose of this protocol is to demonstrate how to optimize the polarization states of the laser light based on the fluorescence of ions in the vacuum system, and how to calculate the birefringence of vacuum windows based on azimuthal angles of external wave plates with Mueller matrix. The fluorescence of 25Mg+ ions induced by laser light that is resonant with the transition of |32P3/2,F = 4, mF&#160;= 4<img align="center" alt="Equation 100" src="/files/ftp_upload/61175/61175img1.jpg" style="color: rgb(68, 0, 68); font-size: 18px; font-weight: 700;" />&#160;&#8594;&#160;|32S1/2,F = 3, mF&#160;= 3<img align="center" alt="Equation 100" src="/files/ftp_upload/61175/61175img1.jpg" style="color: rgb(68, 0, 68); font-size: 18px; font-weight: 700;" />&#160;is sensitive to the polarization state of the laser light, and maximum fluorescence will be observed with pure circularly polarized light. A combination of half-wave plate (HWP) and quarter-wave plate (QWP) can achieve arbitrary phase retardation and is used for compensating the birefringence of the vacuum window. In this experiment, the polarization state of the laser light is optimized based on the fluorescence of 25Mg+ ion with a pair of HWP and QWP outside the vacuum chamber. By adjusting the azimuthal angles of the HWP and QWP to obtain maximum ion fluorescence, one can obtain a pure circularly polarized light inside the vacuum chamber. With the information on the azimuthal angles of the external HWP and QWP, the birefringence of the vacuum window can be determined.

In Situ Measurement of Vacuum Window Birefringence using 25Mg+ Fluorescence

Presented here is a method to measure the birefringence of vacuum windows by maximizing the fluorescence counts emitted by Doppler cooled 25Mg+ ions in an ion trap. The birefringence of vacuum windows will change the polarization states of the laser, which can be compensated by changing the azimuthal angles of external wave plates.

25Mg+ 형광을 사용하여 진공 창 비류의 현장 측정

Accurate control of the polarization states of laser light is important in precision measurement experiments. In experiments involving the use of a vacuum ...

Polarization-Sensitive Two-Photon Microscopy를 이용한 구형석 특성화

Polarization-Sensitive Two-Photon Microscopy for a Label-Free Amyloid Structural Characterization

Compared to its one-photon counterpart, two-photon excitation is beneficial for bioimaging experiments because of its lower phototoxicity, deeper tissue penetration, efficient operation in densely packed systems, and reduced angular photoselection of fluorophores. Thus, the introduction of polarization analysis in two-photon fluorescence microscopy (2PFM) provides a more precise determination of molecular organization in a sample compared to standard imaging methods based on linear optical processes. In this work, we focus on polarization-sensitive 2PFM (ps-2PFM) and its application in the determination of molecular ordering within complex bio-structures-amyloid spherulites. Neurodegenerative diseases such as Alzheimer's or Parkinson's are often diagnosed through the detection of amyloids-protein aggregates formed due to an impaired protein misfolding process. Exploring their structure leads to a better understanding of their creation pathway and consequently, to developing more sensitive diagnostic methods. This paper presents the ps-2PFM adapted for the determination of local fibril ordering inside the bovine insulin spherulites and spherical amyloidogenic protein aggregates. Moreover, we prove that the proposed technique can resolve the three-dimensional organization of fibrils inside the spherulite.

저자 스포트라이트: 편광에 민감한 이광자 현미경을 사용한 복잡한 생체 구조의 비침습적 이미징 

This paper describes how polarization-sensitive two-photon microscopy could be applied to characterize the local organization within label-free amyloid superstructures-spherulites. It also describes how to prepare and measure the sample, assemble the required setup, and analyze the data to obtain information about the local organization of amyloid fibrils.

Label-free Amyloid Structural Characterization을 위한 편광에 민감한 2광자 현미경

Compared to its one-photon counterpart, two-photon excitation is beneficial for bioimaging experiments because of its lower phototoxicity, deeper tissue ...

분극 변수 레이저와 함께 회전 및 각도 해결 광전자 방출 분광학 실험 방법

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