A new type of laser that uses electron spins to generate light

Researchers at the Technion-Israel Institute of Technology have developed a coherent and controllable spin-optical laser based on a single atomic layer. This discovery opens new possibilities for studying and manipulating the interactions between electrons and photons, as well as creating novel optoelectronic devices that exploit both spin and valley degrees of freedom.

What is a spin-optical laser?

A spin-optical laser is a device that uses the spin of electrons to generate light. The spin of electrons is a quantum property that can be used to encode information. By controlling the spin of electrons, researchers can create a laser that is faster, more efficient, and smaller than traditional lasers.

A new type of laser that uses electron spins to generate light
A new type of laser that uses electron spins to generate light

How does it work? The spin-optical laser works by using a combination of magnetic and optical fields to control the spin of electrons. When the spin of electrons is aligned, they emit light. By controlling the magnetic and optical fields, researchers can create a laser that emits light at a specific wavelength and with a specific polarization.

How did the researchers create the spin-optical laser?

The researchers created the spin-optical laser by integrating a single atomic layer of tungsten disulfide (WS2) with a photonic spin lattice. A photonic spin lattice is a structure that creates artificial magnetic fields for photons, resulting in spin-split states in momentum space. These states are characterized by a geometric phase mechanism, also known as the photonic Rashba effect.

The researchers used an inversion-asymmetric core and an inversion-symmetric cladding to construct the photonic spin lattice, which enabled them to confine the spin-split states in a lateral direction. This created high-quality resonances, also known as bound states in the continuum, which enhanced the interaction between the photons and the WS2 monolayer.

The WS2 monolayer is a two-dimensional material that exhibits strong valley-dependent optical selection rules. This means that the electrons in the WS2 monolayer can occupy two different valleys in momentum space, each with a distinct spin polarization. By coupling the WS2 monolayer with the photonic spin lattice, the researchers achieved coherent and controllable spin-valley lasing from the WS2 excitons.

What are the advantages and applications of the spin-optical laser?

The spin-optical laser has several advantages over conventional lasers. First, it does not require external magnetic fields or cryogenic temperatures to operate, making it more compact and practical. Second, it offers high spatial and temporal coherence, as well as tunability of the emission wavelength and polarization. Third, it enables access to both electron and photon spins, as well as their valley degrees of freedom, which can be used for encoding and processing information.

The spin-optical laser has potential applications in various fields, such as quantum optics, quantum information, nanophotonics, optoelectronics, and spintronics. For example, it can be used to study coherent spin-dependent phenomena in both classical and quantum regimes, such as spin Hall effect, spin-orbit coupling, and valley Hall effect. It can also be used to create novel devices that exploit both electron and photon spins, such as spin-valley filters, modulators, switches, detectors, and transistors.

What are the challenges and future directions of the research?

The research team has demonstrated the proof-of-concept of the spin-optical laser based on a single atomic layer. However, there are still some challenges and limitations that need to be overcome before it can be widely applied. For instance, the stability and scalability of the device need to be improved, as well as its integration with other components and systems. Moreover, the performance and functionality of the device need to be optimized and enhanced by exploring different materials, structures, and parameters.

The research team plans to continue their work on developing and improving the spin-optical laser based on atomic-scale materials. They also aim to investigate other coherent and controllable phenomena that emerge from the coupling between atomic layers and photonic lattices. They hope that their research will pave the way for new horizons in fundamental research and optoelectronic devices exploiting both electron and photon spins.

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