Loss-induced suppression and revival of lasing Peng, B.; Özdemir, Ş. K.; Rotter, S. ...
Science (American Association for the Advancement of Science),
10/2014, Letnik:
346, Številka:
6207
Journal Article
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Controlling and reversing the effects of loss are major challenges in optical systems. For lasers, losses need to be overcome by a sufficient amount of gain to reach the lasing threshold. In this ...work, we show how to turn losses into gain by steering the parameters of a system to the vicinity of an exceptional point (EP), which occurs when the eigenvalues and the corresponding eigenstates of a system coalesce. In our system of coupled microresonators, EPs are manifested as the loss-induced suppression and revival of lasing. Below a critical value, adding loss annihilates an existing Raman laser. Beyond this critical threshold, lasing recovers despite the increasing loss, in stark contrast to what would be expected from conventional laser theory. Our results exemplify the counterintuitive features of EPs and present an innovative method for reversing the effect of loss.
We fabricated and theoretically investigated an add-drop filter (ADF) using an on-chip whispering gallery mode (WGM) microtoroid resonator with ultrahigh-quality factor ( Q ) side coupled to two ...taper fibers, forming the bus and drop waveguides. The new device design incorporates silica side walls close to the microresonators which not only enable placing the coupling fibers on the same plane with respect to the microtoroid resonator but also provides mechanical stability, leading to an ADF with high drop efficiency and improved robustness to environmental perturbations. We show that this new device can be thermally tuned to drop desired wavelengths from the bus without significantly affecting the drop efficiency, which is around 57%.
In this paper, we demonstrate a new type of two-dimensional photonic crystal wavelength division demultiplexers based on ring resonators that can be applicable to photonic integrated circuits. The ...proposed structure mechanism is performed based on coupling between a waveguide and a ring resonator. Based on the calculated position, this structure is designed and verified by finite-difference time-domain computation; our simulation by using this method results over 82% output efficiency. We use a heterostructure which is constructed of three different values of dielectric constant to obtain our wavelength division demultiplexer.
In this paper, we demonstrate a new type of 2D photonic crystal T-shaped channel-drop filters based on ring resonators with high normalized transmission; we investigate parameters which affects ...resonant frequency in these channel-drop filters. These parameters include dielectric constant of inner rods, coupling rods and whole rods of the structure as well as radius of the coupling rods and scatterer rods. At dropping case, the power transferred to the drop waveguide and the power remaining in the bus waveguide are found by finite difference time domain (FDTD) method to be over 95% and less than 5%, respectively.
In this paper, theoretical and numerical analysis of low-loss right angle waveguide bends and T-junctions based on ultra-compact photonic crystal ring resonators (PCRR) is presented. Desirable ...characteristics are obtained by designing the waveguide bends and T-junctions as low-
Q resonant cavities with certain symmetries and small radiation loss. A simple analysis, based on coupled mode theory (CMT) in time, is used to explain the operation principles which agree qualitatively with the numerical results. These structures have high transmission efficiency over a large bandwidth in third communication window. Also effects of changing the ring size on power splitter transmission characteristics are discussed. The perfect transmission and zero reflection conditions are discussed by applying coupled mode theory. Results obtained by the finite difference time domain (FDTD) simulations are consistent with those from the coupled mode theory.
In this study, power splitters with different lattice configurations are investigated. First a Y-splitter in a square lattice is presented and compared with its counterpart in hexagonal lattice. Then ...in order to minimize backward reflections and to obtain equal distribution of power we present heterostructure built on hybrid 2-D photonic crystal (PhC) lattice, this structure is a combination of square and hexagonal lattices. Our numeric simulation with finite-difference time-domain (FDTD) technique shows that the heterostructure has better performances. By this structure we achieve an overall throughput efficiency of 94%. Then by applying theoretical approach (Couple Mode theory) transmission properties of T-junctions are optimized and physical mechanism behind them are explained. Also two optimized 90 degree bend with high transmission efficiency are proposed At last, based on these optimized T-junctions and 90 degree bends we propose new 1x4 optical power splitter schemes in PhC with high transmission efficiency and equal splitting ratio over a large bandwidth in third communication window.
We study a system of nonlinearly coupled semiconductor lasers with opto-electronic feedback loops. The lasers are coupled in a way to formulate generalized Lotka-Volterra (GLV) equations. The ...interaction of lasers' phases, intensity and carrier inversion rates result in complex nonlinear dynamics.
A New Broadband Photonic Crystal Add Drop Filter Monifi, F.; Djavid, M.; Ghaffari, A. ...
Journal of applied sciences (Asian Network for Scientific Information),
5/2008, Letnik:
8, Številka:
11
Journal Article
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