Sequential harmonic spin–orbit angular momentum generation in nonlinear optical crystals
非线性光学晶体中顺序谐波自旋轨道角动量的产生
非線形光学結晶における連続調和スピン軌道角運動量生成
비선형 광학 결정에서의 순차적 고조파 스핀-궤도 각운동량 생성
Generación de momento angular armónico secuencial espín-órbita en cristales ópticos no lineales
Génération de moment angulaire spin-orbite harmonique séquentiel dans des cristaux optiques non linéaires
Последовательная гармоническая генерация спин-орбитального углового момента в нелинейных оптических кристаллах
Yutao Tang ¹, Zixian Hu ¹, Junhong Deng ¹, Kingfai Li ¹, Guixin Li ¹ ²
¹ Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
中国 深圳 南方科技大学材料科学与工程系
² Institute for Applied Optics and Precision Engineering, Southern University of Science and Technology, Shenzhen 518055, China
中国 深圳 南方科技大学精密光学工程中心
Light beams carrying multiple orbital angular momentum (OAM) states, which can be realized by the structured media with phase singularities, have attracted great attentions in the fields of high dimensional optical information processing. Alternatively, a simple uniaxial crystal can be used to simultaneously generate four OAM states of light through the second harmonic generation and cascaded optical spin–orbit interaction (SOI) processes.
However, two of the OAM states realized in the crystal are very weak and limit the practical applications. Here, we aim to circumvent this constraint by using the sequential optical SOI processes in two crystals with threefold rotational symmetry. Four angular momentum states of the fundamental waves are prepared after the first crystal and then are utilized to generate the corresponding second harmonic waves (SHWs) with opposite spin and doubled OAM in the second crystal.
Further through a sequential SOI process, totally eight angular momentum states of the SHWs with nearly equal energy are experimentally observed. The proposed methodology may find potential applications in optical communications, parallel optical computing, optical manipulation and so on.
