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Inducing tunable single-mode operation of Fabry-Perot semiconductor laser coupled with very-short cavity with selective optical feedback
摘要： We report on achieving tuned single mode operation of a multimode semiconductor laser by coupling it to a very-short external cavity with selective feedback. We show that the induced uniform feedback light from the very-short external cavity can induce single-mode oscillation over a broad range of optical feedback. Then by applying selective external to the optimum settings of the single-mode oscillation, we predict tuning of the single-mode output over a wavelength range of ~ 20 nm by detuning the peak wavelength of optical feedback from the central wavelength of the modal gain. The study is based on modeling of the dynamics of multimode semiconductor laser subject to selective optical feedback. The model takes into account mechanisms of both self- and cross-modal gain suppression, and the study is concerned with the very-short external cavity that corresponds to stable continuous-wave (CW) operation.
关键词： Optical feedback,Semiconductor laser,Multimode laser,Optical gain
更新于2025-09-23 15:21:01
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Nanocomposites for Photonic and Electronic Applications || Nanocomposite-based random lasers
摘要： First demonstrated in 1960 [1], the laser, as we know today, essentially consists of a pump source, a gain medium, and a cavity composed by a set of mirrors. The role of the cavity is to provide optical feedback, besides determining the directionality and modes of the laser [2]. A few years after the laser invention, V. S. Letokhov proposed in 1967 that coherent oscillation could be generated without the need for the mirror cavity [3], and the optical feedback would be provided by a scattering medium. Several years later, two publications described experimental results of stimulated emission in powders employing rare-earth materials of micron size [4,5]. However, the real breakthrough in the so-called random laser (RL) emission came in 1994 [6], when Lawandy and coworkers employed a nanocomposite prepared from a colloidal suspension of organic dye and nanometer-size TiO2 to clearly demonstrate laser emission in a gain medium in the presence of scatters. In the same year, Sha and coworkers studied the temporal emission of a similar nanocomposite RL with picosecond resolution, thus corroborating the laser action [7].
关键词： optical feedback,photonic devices,random lasers,nanocomposites,plasmonics
更新于2025-09-23 15:21:01
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Encrypted Chaos in Quantum Dot Light Emitting Diode
摘要： A communication scheme based on the synchronization of two chaotic quantum dot light emitting diodes (QD-LEDs) is theoretically examined. The Chaos in the QD-LED is generated by means of an optical feedback. Synchronization of the chaos is achieved by varying coupling strength between the transmitter and the receiver as unidirectional coupling. The proposed communication schemes is test a by successfully transmitting messages.
关键词： chaos synchronization,optical feedback,QD-LED,communication
更新于2025-09-23 15:19:57
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Spectral linewidth reduction of quantum cascade lasers by strong optical feedback
摘要： In this work, we propose to employ strong optical feedback to narrow the spectral linewidth of quantum cascade lasers without using any phase control. Rate equation analysis demonstrates that optical feedback beyond a certain level always reduces the laser linewidth for any feedback phase. It is also found that the linewidth becomes less sensitive to the feedback phase for higher feedback strength. Simulations show that optical feedback with a feedback ratio of ?10 dB can suppress the laser linewidth by about two orders of magnitude. This is in contrast to near-infrared laser diodes, which can be easily destabilized by strong feedback.
关键词： quantum cascade lasers,spectral linewidth reduction,optical feedback
更新于2025-09-23 15:19:57
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Influence of the Fifth-Order Nonlinearity of Gold Nanorods on the Performance of Random Lasers
摘要： We present the first experimental evidence for the influence of the fifth-order nonlinearity on the characteristics of Random Lasers with plasmonic nanoparticles as scatterers. The experiments were performed with gold nanorods suspended in an ethanolic solution of Rhodamine 6G, pumped by a picosecond laser. It is shown that by varying the nanorods aspect-ratio, it is possible to control the cooperative influence of both transverse and longitudinal localized surface plasmons on the fifth-order nonlinear light scattering, a phenomenon that allows to manage the optical feedback causing significant changes in the threshold intensity and emission power of Random Lasers.
关键词： fifth-order nonlinearity,gold nanorods,Random Lasers,optical feedback,plasmonic nanoparticles
更新于2025-09-23 15:19:57
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Quantum stabilization of microcavity excitation in a coupled microcavitya??half-cavity system
摘要： We analyze the quantum dynamics of a two-level emitter in a resonant microcavity with optical feedback provided by a distant mirror (i.e., a half cavity) with a focus on stabilizing the emitter-microcavity subsystem. Our treatment is fully carried out in the framework of cavity quantum electrodynamics. Specifically, we focus on the dynamics of a perturbed subradiant state of the emitter-microcavity subsystem to ascertain its stability (existence of time oscillatory solutions around the candidate state) or lack thereof. In particular, we find conditions under which multiple feedback modes of the half cavity contribute to the stability, showing certain analogies with the Lang-Kobayashi equations, which describe a laser diode subject to classical optical feedback.
关键词： optical feedback,microcavity,Lang-Kobayashi equations,quantum dynamics,two-level emitter,cavity quantum electrodynamics,stability,subradiant state
更新于2025-09-19 17:13:59
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Routes to Chaos of a Semiconductor Laser Subjected to External Optical Feedback: A Review
摘要： This paper reviews experimental investigations of the route to chaos of a semiconductor laser subjected to optical feedback from a distant reflector. When the laser is biased close to threshold, as the feedback strength is increased, an alternation between stable continuous wave (CW) behavior and irregular, chaotic fluctuations, involving numerous external-cavity modes, is observed. CW operation occurs on an external-cavity mode whose optical frequency is significantly lower than that of the solitary laser. The scenario is significantly different for larger currents as the feedback level is increased. At low feedback, the laser displays periodic or quasiperiodic behavior, mostly around external-cavity modes whose frequency is slightly larger than that of the solitary laser. As the feedback level increases, the RF and optical frequencies involved progressively lock until complete locking is achieved in a mixed external-cavity mode state. In this regime, the optical intensity and voltage oscillate at a frequency that is also equal to the optical frequency spacing between the modes participating in the dynamics. For even higher feedback, the locking cannot be maintained and the laser displays fully developed coherence collapse.
关键词： chaos,nonlinear dynamics,semiconductor laser,bifurcations,optical feedback
更新于2025-09-19 17:13:59
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Investigation of Chaotic and Spiking Dynamics in Mid-Infrared Quantum Cascade Lasers Operating Continuous-Waves and Under Current Modulation
摘要： This study investigates chaotic and spiking dynamics of mid-infrared quantum cascade lasers operating under external optical feedback and emitting at 5.5 μm and 9 μm. In order to deepen the understanding, the route to chaos is experimentally studied in the case of continuous-wave and current modulation operation. The non-linear dynamics are analyzed with bifurcation diagrams. While for quasi-continuous wave operation, chaos is found to be more complex, pure continuous wave pumping always leads to the generation of a regular spiking induced low-frequency ?uctuations dynamics. In the latter, results show that by combining external optical feedback with periodic forcing and further induced current modulation allows a better control of the chaotic dropouts. This work provides a novel insight into the development of future secure free-space communications based on quantum cascade lasers or unpredictable optical countermeasure systems operating within the two transparency atmospheric windows hence between 3 μm–5 μm and 8.5 μm–11 μm.
关键词： entrainment phenomenon,quantum cascade laser,secure communications,external optical feedback,mid-infrared photonics,Nonlinear dynamics
更新于2025-09-16 10:30:52
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Precise Photon Correlation Measurement of a Chaotic Laser
摘要： The second order photon correlation g(2)(τ) of a chaotic optical-feedback semiconductor laser is precisely measured using a Hanbury Brown–Twiss interferometer. The accurate g(2)(τ) with non-zero delay time is obtained experimentally from the photon pair time interval distribution through a ninth-order self-convolution correction. The experimental results agree well with the theoretical analysis. The relative error of g(2)(τ) is no more than 5‰ within 50 ns delay time. The bunching effect and coherence time of the chaotic laser are measured via the precise photon correlation technique. This technique provides a new tool to improve the accuracy of g(2)(τ) measurement and boost applications of quantum statistics and correlation.
关键词： optical feedback,chaos,quantum optics,photon correlation,photon statistics,semiconductor lasers
更新于2025-09-16 10:30:52
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High coherence collapse of a hybrid III-V/Si semiconductor laser with a large quality factor
摘要： The high-speed dynamics of a hybrid distributed feedback semiconductor laser heterogeneously integrated onto silicon is experimentally investigated in the presence of external optical feedback. The laser fabrication relies on a proper modal engineering in which light is generated in the III-V material and stored in the low-loss silicon region in order to substantially enhance the quality factor of the cavity resonator. In this work, the hybrid laser is found to be insensitive to parasitic re?ections leading to a 10 Gbps ?oor-free transmission with a power penalty no greater than 1.5 dB at room temperature. As a conclusion, owing to the large quality factor, a high coherence collapse level is unveiled in such laser indicating its vast potential to serve as an alternative solution for the development of isolator-free applications in future photonics integrated circuits. A qualitative interpretation is also provided by linking the standard feedback equations to the quality factor of the resonator.
关键词： optical feedback,Semiconductor lasers,photonics integrated circuits.
更新于2025-09-16 10:30:52