Scientists have developed the first liquid nanoscale laser and it's tunable in real time, meaning you can quickly and simply produce different colors, a unique and useful feature. The laser technology could lead to practical applications, such as a new form of a "lab on a chip" for medical diagnostics.The laser's color can be changed in real time when the liquid dye in the microfluidic channel above the laser's cavity is changed.
The laser's cavity is made up of an array of reflective gold nanoparticles, where the light is concentrated around each nanoparticle and then amplified. (In contrast to conventional laser cavities, no mirrors are required for the light to bounce back and forth.) Notably, as the laser color is tuned, the nanoparticle cavity stays fixed and does not change; only the liquid gain around the nanoparticles changes.
In addition to changing color in real time, the liquid nanolaser has additional advantages over other nanolasers, in that it is simple to make, inexpensive to produce and operates at room temperature. Nanoscopic lasers -- first demonstrated in 2009 -- are only found in research labs today. Plasmon lasers are promising nanoscale coherent sources of optical fields because they support ultra-small sizes and show ultra-fast dynamics.
Although plasmon lasers have been demonstrated at different spectral ranges, from the ultraviolet to near-infrared, a systematic approach to manipulate the lasing emission wavelength in real time has not been possible.
The main limitation is that only solid gain materials have been used in previous work on plasmon nanolasers; hence, fixed wavelengths were shown because solid materials cannot easily be modified. A research team led by Professor Teri Odom of Northwestern has found a way to integrate liquid gain materials with gold nanoparticle arrays to achieve nanoscale plasmon lasing that can be tuned dynamical, reversibly and in real time.
