Departmental Seminar

III-V nanowire-based random laser in the Anderson Localization regime

Mr Mohammad Rashidi

As opposed to the reflective feedback by the mirrors of a conventional laser, random laser’s (RL’s) feedback mechanism is based on multiple random scattering resulting from fluctuation of the dielectric constant in disordered materials. This alternative feedback mechanism has an important application to lasers in the spectral regime where an efficient reflective element is not available, e.g., UV laser, x-ray laser. Besides, this unconventional feedback mechanism in RLs leads to properties interesting from both fundamental and practical point of view

In the recent years, random lasers due to their narrow linewidth emission signature, nano or micron size, strong light localization capability, bright lasing emission, low spatial coherence, high effective optical path, feasibility to be coated on different surfaces, very broad angular distribution (or angle-free emissions), mirrorless cavity and low cost have attracted lots of interests. These unique properties have made random lasers a suitable candidate for different applications, including dye-circulated structured microfluidic channels, opto-fluidic bio-lasers, optical batteries, cancer diagnostic, speckle-free full-field imaging, lab-on-a-chip random spectrometers, time-resolved microscopies, sensors, random distributed feedback fiber lasers, laser paints, and military purposes.

One of the main challenges in random lasers is the instability of the system, making the device difficult to be controlled and tuned. However, in the Anderson localization regime, due to the exponential confinement, the spatial overlap between lasing modes is suppressed, leading to stable multi-mode lasing which can be used for tunable purposes.

Here, using InP nanowires and designing the random media to work in the Localization regime, multi-mode stable random laser is reported. We can also  tune the properties of the lasing modes by changing the geometry properties.

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