Arbitrary helicity control of circularly polarized light from lateral-type spin-polarized light-emitting diodes at room temperature

In traditional optoelectronic approaches, control over spin, charge, and light requires the use of both electrical and magnetic fields. In a spin-polarized light-emitting diode (spin-LED), charges are injected, and circularly polarized light is emitted from spin-polarized carrier pairs. Typically, the injection of carriers occurs with the application of an electric field, whereas spin polarization can be achieved using an applied magnetic field or polarized ferromagnetic contacts. We used chiral-induced spin selectivity (CISS) to produce spin-polarized carriers and demonstrate a spin-LED that operates at room temperature without magnetic fields or ferromagnetic contacts. The CISS layer consists of oriented, self-assembled small chiral molecules within a layered organic-inorganic metal-halide hybrid semiconductor framework. The spin-LED achieves ±2.6% circularly polarized electroluminescence at room temperature.

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Pure circular polarization electroluminescence at room temperature with spin-polarized light-emitting diodes

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1609839114 ◽

2017 ◽

Vol 114 (8) ◽

pp. 1783-1788 ◽

Cited By ~ 24

Author(s):

Nozomi Nishizawa ◽

Kazuhiro Nishibayashi ◽

Hiro Munekata

Keyword(s):

Circular Polarization ◽

Room Temperature ◽

Light Emitting Diodes ◽

Polarized Light ◽

Tunnel Barrier ◽

Light Emitting ◽

Left Handed ◽

Spin Polarized ◽

Side Walls ◽

Device Operation

We report the room-temperature electroluminescence (EL) with nearly pure circular polarization (CP) from GaAs-based spin-polarized light-emitting diodes (spin-LEDs). External magnetic fields are not used during device operation. There are two small schemes in the tested spin-LEDs: first, the stripe-laser-like structure that helps intensify the EL light at the cleaved side walls below the spin injector Fe slab, and second, the crystalline AlOxspin-tunnel barrier that ensures electrically stable device operation. The purity of CP is depressively low in the low current density (J) region, whereas it increases steeply and reaches close to the pure CP whenJ> 100 A/cm2. There, either right- or left-handed CP component is significantly suppressed depending on the direction of magnetization of the spin injector. Spin-dependent reabsorption, spin-induced birefringence, and optical spin-axis conversion are suggested to account for the observed experimental results.

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Lateral-Type Spin-Photonics Devices: Development and Applications

Micromachines ◽

10.3390/mi12060644 ◽

2021 ◽

Vol 12 (6) ◽

pp. 644

Author(s):

Nozomi Nishizawa ◽

Hiro Munekata

Keyword(s):

Room Temperature ◽

Polarized Light ◽

Photonic Devices ◽

Future Prospects ◽

Circularly Polarized Light ◽

Light Emitting ◽

Current State ◽

Spin Polarized ◽

Photonics Devices ◽

Room Temperature Operation

Spin-photonic devices, represented by spin-polarized light emitting diodes and spin-polarized photodiodes, have great potential for practical use in circularly polarized light (CPL) applications. Focusing on the lateral-type spin-photonic devices that can exchange CPL through their side facets, this review describes their functions in practical CPL applications in terms of: (1) Compactness and integrability, (2) stand-alone (monolithic) nature, (3) room temperature operation, (4) emission with high circular polarization, (5) polarization controllability, and (6) CPL detection. Furthermore, it introduces proposed CPL applications in a wide variety of fields and describes the application of these devices in biological diagnosis using CPL scattering. Finally, it discusses the current state of spin-photonic devices and their applications and future prospects.

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