Random super-prism wavelength meter
In a recent paper published in Optics Letter we demonstrate that a random medium can be used as a cheap and reliable wavemeter. The system is made of a small drop of alumina particles in water solution casted on a glass slide, placed at the end of a fiber coupler as in figure. When propagating through the drop, light of different wavelengths produce specific speckle patterns that can be stored for future reference. The unknown wavelength of a further beam can then be assessed using principal component analysis with a resolution up to 13 pm.