arXiv subjects

T. Grosjean

Publications and source records attributed to T. Grosjean.

5 recordsLinked to original sources

arXiv2018

Controlling light polarization by swirling surface plasmons

Light polarization is a key aspect of modern optics. Current methods for polarization control utilize birefringence and dichroism of anisotropic materials or of arrays of anisotropically shaped nanostructures. Based on collective optical effects, the resulting components remain much larger than the wavelength of light, which limits design strategies. Here, we present a travelling-wave plasmonic antenna that overcomes this limit using a gold-coated helical nanowire non-radiatively fed with a dipolar aperture nanoantenna. Our non-resonant hybrid nanoantenna enables tightly confined circularly polarized light by swirling surface plasmons on the subwavelength scale and taking advantage of optical spin-orbit interaction. Four closely packed circularly polarized light sources of opposite handedness and tunable intensities are demonstrated. By reaching near-field interaction between neighboring nanoantennas, we obtain a highly miniaturized wave plate whose polarization properties have never previously been demonstrated.

physics.optics↗

arXiv2017

Directing nanoscale optical flows by coupling photon spin to plasmon extrinsic angular momentum

As any physical object, light undergoing a circular trajectory features a constant extrinsic angular momentum. Within strong curvatures, this angular momentum can match the spin momentum of a photon, thus providing the opportunity of a strong spin-orbit interaction. Using this effect, we demonstrate tunable symmetry breaking in the coupling of light in a curved nanoscale plasmonic waveguide. The helicity of the impinging optical wave controls the power distribution between the two counter-propagating guided modes, including unidirectional waveguiding. We found that up to 95 % of the incoupled light can be directed into one of the two propagation directions of the waveguide. This approach offers appealing new prospects for the development of advanced, deeply subwavelength optical functionalities.

physics.optics↗

arXiv2016

Fiber-integrated single photon source of high efficiency based on a concept of ultra-broadband optical horn antenna

We theoretically demonstrate a fiber-integrated single photon source of unprecedented efficiency. This fiber single photon source is achieved by coupling optically a single quantum emitter to a monomode optical fiber with a new concept of ultra-broadband optical antenna. Such an optical antenna concept is the result of the transposition to optical frequencies of the well-known low-frequency horn antenna The optical horn antenna is here shown to be capable of directing the radiation from the emitter toward the optical fiber and efficiently phase-matching the photon emission with the fiber mode. Numerical results show that an optical horn antenna can funnel up to 85% of the radiation from a dipolar source within an emission cone semi-angle as small as 7 degrees (antenna directivity of 300). It is also shown that 50% of the emitted power from the dipolar source can be collected and coupled to an SMF-28 fiber mode over spectral ranges larger than 1000 nm, with a maximum energy transfer reaching 70 %. This approach is highly promising in the engineering of all-fiber "on-demand" single photon sources for telecommunication, quantum optics and sensing.

physics.optics↗

arXiv2013

Far-field mapping of the longitudinal magnetic and electric optical fields

In this letter, we demonstrate the experimental mapping of the longitudinal magnetic and electric optical fields with a standard scanning microscope that involves a high numerical aperture far-field objective. The imaging concept relies upon the insertion of an azimuthal or a radial polarizer within the detection path of the microscope which acts as an optical electromagnetic filter aimed at transmitting selectively to the detector the signal from the magnetic or electric longitudinal fields present in the detection volume, respectively. The resulting system is thus versatile, non invasive, of high resolution, and shows high detection efficiencies. Magnetic optical properties of physical and biological micro and nano-structures may thus be revealed with a far-field microscope.

physics.optics↗

arXiv2012

All-fiber controller of radial polarization using a periodic stress

Our aim is to transpose the polarization control by mechanical stress usually applied to single mode fibers, to the (TM01, TE01,HEev21,HEod21) annular mode family. Nevertheless, the quasi degeneracy of these four modes makes the situation more complex than with the fundamental mode HE11. We propose a simple device based on periodic perturbation and mode coupling to produce the radially polarized TM01 mode or at least one single of the four modes at the extremity of an arbitrarily long fiber, the conversion to TM01 mode being achievable by classical crystalline plates.

physics.optics↗