Selective variable optical attenuator for visible and mid-Infrared wavelengths

This work demonstrates a variable optical attenuator (VOA) using dynamic scattering mode (DSM) in ion-doped liquid crystals with negative dielectric anisotropy. The mechanism of attenuation comes from optical scattering, which is generated by the electrically induced instability of undulation of LC textures. Electric fields are applied to switch the initial transparent state of the designed VOA to scattering states, varying the transmittance. The electric field also changes the size of the scattering domain from the LC texture and causes the designed device to exhibit an ultra-broadband selective operation in a visible to mid-IR spectral range. Furthermore, the VOA can selectively block one visible or mid-IR wavelength of light while letting other light pass. Such a VOA has many superior optical switching properties, such as high on/off contrast, insensitivity to polarization, and spectral selectivity; therefore, it has the potential to be used in practical optical systems.