Optical isolators which serve as one-way optical channels are a crucial component in numerous applications [1]. To obtain optical isolation, the time reversal symmetry must be broken. This braking of time reversal symmetry is usually done via Faraday rotator with constant magnetic field [2] and was also demonstrated with nonlinear interaction of traveling pump waves [3] and with circular polarized light manipulations [4].

We present, optical isolator based on the interaction between light and topological isolators. Our optical isolator is free from external magnetic field and is based on spontaneous time reversal symmetry braking by the topological insulators. The time reversal symmetry braking is obtained through the interaction of the traveling light in tapered fiber with the topological electrons in the surface and in the bulk of Sb₂Te₃ nano-particles. The interaction of light with the topological electrons rotates the input polarization similar to the Faraday rotator but with no external magnetic field.

Our technique can lead to novel type of non-reciprocal fiber devices and can be implemented in on-chip photonic waveguides. The full experimental and theoretical details of our optical isolator will be presented.

 References:

[1] D. Jalas, et. al. “What is – and what is not – an optical isolator” Nat. Photon. 7, 579 (2013)

[2] K. Shiraishi, S. Sugaya, and S. Kawakami, "Fiber Faraday rotator," Appl. Opt. 23, 1103 (1984)

[3] H. Ramezani, T. Kottos, R. El-Ganainy, and D. N. Christodoulides Phys. Rev. A 82, 043803 (2010)

[4] J. W. Goodman “Introduction to Fourier optics” (2005)