Karnieli Aviv, Arie Ady
Opt Express. 2018 Feb 19;26(4):4920-4932. doi: 10.1364/OE.26.004920.
We propose and analyze a new way for obtaining an adiabatic geometric phase for light, via the sum-frequency-generation nonlinear process. The state of light is represented by the complex amplitudes at two different optical frequencies, coupled by the second order nonlinearity of the medium. The dynamics of this system is then shown to be equivalent to that of a spin-1/2 particle in a magnetic field, which in turn can be rotated adiabatically on the Bloch sphere. When the input wave itself is an eigenstate of the magnetic field equivalent, the geometric phase is manifested as a pure phase factor. Two adiabatic rotation schemes, based on specific modulations of the quasi-phase-matching poling parameters, are discussed. In the first, the geometric phase is shown to be sensitive to the pump intensity variations, as a result of the Bloch sphere deformation. The second can be utilized for the realization of nonlinear-optics-based geometric phase plates. Moreover, non-closed adiabatic trajectories are investigated, which are expected to provide a robust and broadband geometric wavefront shaping in the sum frequency.
我们提出并分析了一种通过和频产生非线性过程来获取光的绝热几何相位的新方法。光的状态由两个不同光频率处的复振幅表示，它们通过介质的二阶非线性相互耦合。然后证明该系统的动力学等同于磁场中自旋 - 1/2 粒子的动力学，而自旋 - 1/2 粒子又可以在布洛赫球上绝热旋转。当输入波本身是等效磁场的本征态时，几何相位表现为一个纯相位因子。讨论了基于准相位匹配极化参数的特定调制的两种绝热旋转方案。在第一种方案中，由于布洛赫球变形，几何相位被证明对泵浦强度变化敏感。第二种方案可用于实现基于非线性光学的几何相位板。此外，还研究了非闭合绝热轨迹，预计它们能在和频中提供稳健且宽带的几何波前整形。
