Abstract
One of the long-sought-after goals in light manipulation is tuning of transmitted interference colours. Previous approaches toward this goal include material chirality, strain and electric-field controls. Alternatively, colour control by magnetic field offers contactless, non-invasive and energy-free advantages but has remained elusive due to feeble magneto-birefringence in conventional transparent media. Here we demonstrate an anomalously large magneto-birefringence effect in transparent suspensions of magnetic two-dimensional crystals, which arises from a combination of a large Cotton-Mouton coefficient and relatively high magnetic saturation birefringence. The effect is orders of magnitude stronger than those previously demonstrated for transparent materials. The transmitted colours of the suspension can be continuously tuned over two-wavelength cycles by moderate magnetic fields below 0.8 T. The work opens a new avenue to tune transmitted colours, and can be further extended to other systems with artificially engineered magnetic birefringence.
Highlights
One of the long-sought-after goals in light manipulation is tuning of transmitted interference colours
Most of the results presented below have been obtained on a 2D cobalt-doped titanium oxide (CTO) suspension with a volume concentration of 0.02 vol%, exhibiting a high transmittance over visible λ (Supplementary Fig. 1f)
Detailed analysis shows that, to achieve magnetic tunability of the colour of transmitted light, one needs to drive the birefringent system to at least the second-order of the constructive interference condition, which corresponds to the phase retardation δ ≥ 3π
Summary
One of the long-sought-after goals in light manipulation is tuning of transmitted interference colours. With a suitable combination of Δn and L, the wavelength-dependent intensity can be modulated to achieve different colours Such spectral tuning has been achieved by electric-field-controlled birefringence effect in organic liquid crystals[5,6,7,8], and recently been extended to material chirality and strain control[3,4]. To the best of our knowledge, no attempt has ever been made to use magneto-birefringence effect to achieve the spectral tuning by magnetic field control, which has the contactless, non-invasive and energy-free edge and is, more appealing in application aspects Such a void is likely due to difficulties in achieving sufficiently large phase retardation δ, as a result of either weak magneto-optical response or ultra-low saturation magneto-birefringence of conventional transparent media[13,14,15].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
