The basic principle involves using circularly polarized photons to excite electrons in a semiconductor. When these photons interact with the material, they impart their angular momentum to the electrons, causing them to align their spins. The process can be summarized in the following steps: 1. Absorption of circularly polarized light. 2. Excitation of electrons from the valence band to the conduction band. 3. Alignment of electron spins due to the angular momentum of the absorbed photons. 4. Injection of these spin-polarized electrons into a target material or region.
