Nanoscale nonreciprocity via photon-spin-polarized stimulated Raman scattering

Abstract

Time reversal symmetry stands as a fundamental restriction on the vast majority of optical systems and devices. The reciprocal nature of Maxwell’s equations in linear, time-invariant media adds complexity and scale to photonic diodes, isolators, circulators and also sets fundamental efficiency limits on optical energy conversion. Though many theoretical proposals and low frequency demonstrations of nonreciprocity exist, Faraday rotation remains the only known nonreciprocal mechanism that persists down to the atomic scale. Here, we present photon-spin-polarized stimulated Raman scattering as a new nonreciprocal optical phenomenon which has, in principle, no lower size limit. Exploiting this process, we numerically demonstrate nanoscale nonreciprocal transmission of free-space beams at near-infrared frequencies with a 250 nm thick silicon metasurface as well as a fully-subwavelength plasmonic gap nanoantenna. In revealing all-optical spin-splitting, our results provide a foundation for compact nonreciprocal communication and computing technologies, from nanoscale optical isolators and full-duplex nanoantennas to topologically-protected networks.

Helicity‐Preserving Metasurfaces for Magneto‐Optical Enhancement in Ferromagnetic [Pt/Co]N Films

“…The sense of this rotation projected in‐plane perpendicular to the magnetization axis, , was normalized to electric field strength, and averaged over the ferromagnetic layer when illuminated with LCP. [ 50 ] With both t oxide = 30 and 100 nm, this mean rotation within the ferromagnetic film (ϖ) is enhanced by p e and suppressed by p m ( Figure a,b). Maximum ϖ was calculated near p e for the largest disk size when t oxide = 30 nm.…”

“…Significantly enhanced electric near‐field intensities and local electric field rotation with higher‐quality‐factor resonances [ 55 ] may also be obtained via symmetry breaking in biperiodic lattices of nanodisk resonators. [ 43,50 ] Moreover, designs in which the ferromagnetic layer itself is patterned into arrays, channels, or racetrack architectures could minimize radiative damping of p m modes. [ 56–58 ]…”

“…Significantly enhanced electric near-field intensities and local electric field rotation with higher-quality-factor resonances [55] may also be obtained via symmetry breaking in biperiodic lattices of nanodisk resonators. [43,50] Moreover, designs in which the ferromagnetic layer itself is patterned into arrays, channels, or racetrack architectures could minimize radiative damping of p m modes. [56][57][58] In summary, independently tuning Mie-type dipolar resonances within dielectric metasurfaces to control the field extrusion outside of the nanoantennas enables locally confined, multifold enhancement in electric field rotation within proximal ferromagnetic films.…”

Up‐And‐Coming Advances in Optical and Microwave Nonreciprocity: From Classical to Quantum Realm

“…An approach that exploits both unidirectional gain effect and chiral light‐matter coupling has been proposed in the study by Lawrence and Dionne. [ 53 ] This work takes advantage of enhanced stimulated Raman scattering of crystalline Si [ 287,288 ] for Raman amplification of circularly polarized light. The Raman amplification is spin‐locked by choice of the spin of the pumping field.…”

“…Recently novel avenues to achieve nonreciprocity of electromagnetic fields without magnets but using new scattering effects and a new class of materials and metamaterials have been implemented. [ 16–21 ] The examples include dynamic spatiotemporal modulation of parameters, [ 22–25 ] synthetic magnetic field, [ 25–27 ] angular momentum biasing in photonic or acoustic systems, [ 21,28,29 ] nonlinearity, [ 30–33 ] interband photonic transitions, [ 34,35 ] optomechanics, [ 36–40 ] optoacoustics, [ 41,42 ] parity‐time (PT)‐symmetry breaking, [ 43–45 ] unidirectional gain and loss, [ 46–53 ] moving/rotating cavities [ 54–56 ] and emitters, [ 57 ] Doppler‐shift, [ 58 ] chiral light‐matter coupling and valley polarization, [ 59–63 ] and quantum nonlinearity. [ 64–67 ] Furthermore, quantum systems based on superconducting Josephson junctions attract much attention as they hold a great promise for quantum computing.…”