An Introduction to Nanowire Lasers

Topics Covered

Nanowire Laser Technology
Research and Development in Nanowire Lasers
Applications of Nanowire Lasers
Conclusion
References

Nanostructures have been under extensive research due to their distinct properties. The capability of nanostructures to restrain electrons, phonons and photons enables researchers to study the basic optical, mechanical, thermal and electronic properties of these structures.

Studies on single nanowires and other nanostructures are paving the way for next-generation photonic devices such as optically and electrically pumped nanowire lasers. While the fundamentals of traditional laser technologies are well understood, a great deal of research has been focused on investigating nanowire laser technology.

Nanowire Laser Technology

A number of high band gap semiconductors have been used to produce nanowires which exhibit stimulated emission. For instance, ZnS9, CdS7,8, GaN5,6, and ZnO2-4 nanowires that employ far-field and near-field imaging techniques are currently under research. The photoluminescent properties of these semiconductor nanowires strongly exhibit two-dimensional confinement at visible and ultraviolet range. This wave guiding nature of nanowires is dependent on the wavelength of light, and composition and size of nanowires.

Several polarization studies have revealed that pumping of nanowires with pulsed laser light can enhance the transition from spontaneous emission to stimulated emission. Researchers also found that nanowire waveguiding systems exhibit multimode behavior and high intensity of photoluminescence in both far and near field regions. The photoluminescence intensity of these lasers increases linearly with excitation energy until the lasing threshold is met.

Research and Development in Nanowire Lasers

In 2011, a research team from China published an article on a new single nanowire laser that offers significant advantages in a controllable single mode. They excited a looped nanowire with a pulsed laser and observed lasing activity as two bright spots at the ends of nanowire during the round-trip gain.

The nanowire was found to be folded into loops, which reduce lasing threshold and improve reflectivity of nanowire to develop a high-quality lasing cavity. Also, changing the loop size of nanowire enabled the researchers to fine-tune the wavelength of the laser.

Recently, researchers from Arizona State University and Zhejiang University developed a novel nanowire laser with distinct properties by combining photons and plasmons together. The photon-plasmon nanowire lasers are capable of emitting light that is more confined than the light emitted by conventional photon lasers.

These lasers offer ultra-fast modulation and very thin laser beam, which makes them suitable for applications involving ultra-fast modulated coherent sources, ultra-sensitivity optical sensing and strong coupling of quantum nanoemitters.

The researchers also demonstrated that coupling plasmon and photon nanowire waveguides along the beam direction spatially separates the plasmonic mode from the photonic mode to simultaneously use both modes.

Another research team from the Australian National University recently demonstrated the process of developing gallium arsenide (GaAs) that serves as lasers at room temperature. They added nanowires to a substrate scattered with gold particles and supplied gases containing arsenic and gallium to increase the temperature of the substrate. The team explained that these GaAs-based nanowire lasers formed with Fabry–Pérot cavities work by collecting light and reflecting it along the direction of light.

Applications of Nanowire Lasers

Some of the areas nanowire lasers could find potential applications in include:

  • Optical communications
  • Signal processing applications
  • Planetary terrain-ranging
  • Computational technology
  • Spectroscopic sensing

Conclusion

Nanostructures serve as intriguing materials for future photonic applications. It has been shown that chemically synthesized nanowires offer a unique material platform for producing photonic elements including lasers.

Optical experiments reveal that single nanowires exhibit remarkable lasing activities. On the other hand, electrically injected lasers made from semiconducting nanowires offer a different approach for fabricating fully integrated photonic devices.

However, all these current technologies give only limited choices of power level, tunability and wavelength range. Hence, researchers feel that revolutionary new approaches are required in the future to broaden the applications of nanowire lasers and significantly enhance the performance characteristics of existing technology.

References and Further Reading

 

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