13 research outputs found
Probing topological invariants in the bulk of a non-Hermitian optical system
Topological insulators are insulating in the bulk but feature conducting
states on their surfaces. Standard methods for probing their topological
properties largely involve probing the surface, even though topological
invariants are defined via the bulk band structure. Here, we utilize
non-hermiticy to experimentally demonstrate a topological transition in an
optical system, using bulk behavior only, without recourse to surface
properties. This concept is relevant for a wide range of systems beyond optics,
where the surface physics is difficult to probe
第923回千葉医学会例会・第11回磯野外科例会
Topological, NOON, with disorder Originally published in Optica on 20 September 2016 (optica-3-9-925
Topological Lasers
We present the first topological laser: topologically-protected lasing in photonic honeycomb lattices. We show that the lasing modes are unidirectional and robust to defects
Mode-Locked Topological Insulator Laser Utilizing Synthetic Dimensions
We propose a system that exploits the fundamental features of topological photonics and synthetic dimensions to force many semiconductor laser resonators to synchronize, mutually lock, and under suitable modulation emit a train of transform-limited mode-locked pulses. These lasers exploit the Floquet topological edge states in a 1D array of ring resonators, which corresponds to a 2D topological system with one spatial dimension and one synthetic frequency dimension. We show that the lasing state of the multielement laser system possesses the distinct characteristics of spatial topological edge states while exhibiting topologically protected transport. The topological synthetic-space edge mode imposes a constant-phase difference between the multifrequency modes on the edges, and together with modulation of the individual elements forces the ensemble of resonators to mode lock and emit short pulses, robust to disorder in the multiresonator system. Our results offer a proof-of-concept mechanism to actively mode lock a laser diode array of many lasing elements, which is otherwise extremely difficult due to the presence of many spatial modes of the array. The topological synthetic-space concepts proposed here offer an avenue to overcome this major technological challenge and open new opportunities in laser physics