There have been increasing research efforts in using a disordered medium as a next-generation optical element in terms of deterministically controlling scattered waves. While traditional optical elements are dependent on refraction and diffraction rules, which necessitate to occupy sufficiently large space to resolve different wavelength, providing fundamental trade-off limit between form-factor and spectral resolution. Until now, the spatial property of disordered medium was highlighted in view of producing a high transverse wave vector up to the classical limit. Here, we expand viewpoint to the spectral domain where the spectral(temporal) properties of scattered waves are deterministically exploited
More specifically, we investigated trade-off relation between spectral resolution and field of view quantitatively using ZnO-based disordered medium in the visible range of 560-600nm. Exploiting the knowledge about spectral response above, ZnO-based spectrometer is plausible. By measuring the wavelength dependent speckle pattern, input-output response(i.e. transmission matrix) was calibrated. When we sum up wavelength dependent speckle into a single image as spectral target, this spectrometer can distinguish 25 independent color channels.
Disorder-engineered metasurface was recently suggested to design transmission matrix of scattering process. Metasurface framework shows unique property of calibration-free feature. With advantages including high transmittance, and the degrees of freedom in scattering parameters – anisotropy constant and thickness, this new platform to implement an artificial 3-D disordered medium has a great potential in hyperspectral imaging.