ترغب بنشر مسار تعليمي؟ اضغط هنا

Engineered optical nonlinearities and enhanced light transmission in soft-matter systems with tunable polarizabilities

111   0   0.0 ( 0 )
 نشر من قبل Zhigang Chen
 تاريخ النشر 2013
  مجال البحث فيزياء
والبحث باللغة English




اسأل ChatGPT حول البحث

In this work, we demonstrate that the nonlinear response of certain soft-matter systems can be tailored at will by appropriately engineering their optical polarizability. In particular, we deliberately synthesize stable colloidal suspensions with negative polarizabilities, and observe for the first time robust propagation and enhanced transmission of self-trapped light over long distances that would have been otherwise impossible in conventional suspensions with positive polarizabilities. What greatly facilitates this behavior is an induced saturable nonlinear optical response introduced by the thermodynamic properties of these colloidal systems. This in turn leads to a substantial reduction in scattering via self-activated transparency effects. Our results may open up new opportunities in developing soft-matter systems with tunable optical nonlinearities.



قيم البحث

اقرأ أيضاً

A theoretical variation between the two distinct light-matter coupling regimes, namely weak and strong coupling, becomes uniquely feasible in open optical Fabry-Perot microcavities with low mode volume, as discussed here. In combination with monolaye rs of transition-metal dichalcogenides (TMDCs) such as WS2, which exhibits a large exciton oscillator strength and binding energy, the room-temperature observation of hybrid bosonic quasiparticles, referred to as exciton-polaritons and characterized by a Rabi splitting, comes into reach. In this context, our simulations using the transfer-matrix method show how to tailor and alter the coupling strength actively by varying the relative field strength at the excitons position - exploiting a tunable cavity length, a transparent PMMA spacer layer and angle-dependencies of optical resonances. Continuously tunable coupling for future experiments is hereby proposed, capable of real-time adjustable Rabi splitting as well as switching between the two coupling regimes. Being nearly independent of the chosen material, the suggested structure could also be used in the context of light-matter-coupling experiments with quantum dots, molecules or quantum wells. While the adjustable polariton energy levels could be utilized for polariton-chemistry or optical sensing, cavities that allow working at the exceptional point promise the exploration of topological properties of that point.
Pristine, undoped graphene has a constant absorption of 2.3 % across the visible to near-infrared (VIS-NIR) region of the electromagnetic spectrum. Under certain conditions, such as nanostructuring and intense gating, graphene can interact more robus tly with VIS-NIR light and exhibit a large nonlinear optical response. Here, we explore the optical properties of graphene/LaAlO$_3$/SrTiO$_3$ nanostructures, where nanojunctions formed at the LaAlO$_3$/SrTiO$_3$ interface enable large (~10$^8$ V/m) electric fields to be applied to graphene over a scale of ~10 nm. Upon illumination with ultrafast VIS-NIR light, graphene/LaAlO$_3$/SrTiO$_3$ nanostructures produce broadband THz emission as well as a sum-frequency generated (SFG) response. Strong spectrally sharp, gate-tunable extinction features (>99.99%) are observed in both the VIS-NIR and SFG regions alongside significant intensification of the nonlinear response. The observed gate-tunable strong graphene-light interaction and nonlinear optical response are of fundamental interest and open the way for future exploitation in graphene-based optical devices.
We analyze both theoretically and by means of numerical simulations the phenomena of filamentation and dynamical formation of self-guided nonlinear waves in media featuring competing cubic and quintic nonlinearities. We provide a theoretical descript ion of recent experiments in terms of a linear stability analysis supported with simulations, showing the possibility of experimental observation of the modulational instability suppression of intense light pulses travelling across such nonlinear media. We also show a novel mechanism of indirect excitation of {em light condensates} by means of coalescence processes of nonlinear coherent structures produced by managed filamentation of high power laser beams.
We propose a cavity QED scheme to enable cross-phase modulation between two arbitrarily weak classical fields in the optical domain, using organic molecular photoswitches as a disordered intracavity nonlinear medium. We show that a long-lived vibrati onal Raman coherence between the $cis$ and $trans$ isomer states of the photoswitch can be exploited to establish the phenomenon of vacuum-induced transparency (VIT) in high-quality microcavities. We exploit this result to derive an expression for the cross-phase modulation signal and demonstrate that it is possible to surpass the detection limit imposed by absorption losses, even in the presence of strong natural energetic and orientational disorder in the medium. Possible applications of the scheme include the development of organic nanophotonic devices for all-optical switching with low photon numbers.
Despite tremendous advances in the fundamentals and applications of cavity quantum electrodynamics (CQED), investigations in this field have primarily been limited to optical cavities composed of purely dielectric materials. Here, we demonstrate a hy brid metal-dielectric nanocavity design and realize it in the InAs/GaAs quantum photonics platform utilizing angled rotational metal evaporation. Key features of our nanometallic light-matter interface include: (i) order of magnitude reduction in mode volume compared to that of leading photonic crystal CQED systems; (ii) surface-emitting nanoscale cylindrical geometry and therefore good collection efficiency; and finally (iii) strong and broadband spontaneous emission rate enhancement (Purcell factor ~ 8) of single photons. This light-matter interface may play an important role in quantum technologies.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا