Improving the Modulation Bandwidth in Semiconductor Lasers by Passive Feedback

Radziunas, Mindaugas; Glitzky, Annegret; Bandelow, U.; Wolfrum, Matthias; Troppenz, U.; Kreissl, J.; Rehbein, W.

doi:10.1109/jstqe.2006.885332

Cited by 132 publications

(67 citation statements)

References 17 publications

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“…The response to external modulations or perturbations [RAD07,GRI11], the laser linewidth [HEN82], and the occurrence of dynamical instabilities as well as pattern formation in spatially extended laser systems [SMO02,RIB03] all crucially depend on this amplitude-phase coupling. Throughout the literature, this connection is commonly described by assuming a linear relationship between changes of the resonance frequency shift and gain.…”

Section: Amplitude-phase Coupling In Quantum-dot Lasersmentioning

confidence: 99%

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Lingnau

2015

Springer Theses

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In this thesis the dynamics and performance of optoelectronic devices based on semiconductor quantum-dots are investigated.In the first part, the dynamics of quantum-dot lasers under external perturbations is discussed. Using a microscopically based balance equation model that incorporates detailed charge-carrier scattering dynamics and the possibility to describe nonequilibrium between intra-band electronic states, the relaxation oscillations of the quantum-dot laser are investigated. Three qualitatively different dynamic regimes are identified in dependence of the scattering rates -the "constantreservoir" regime for slow scattering, the "overdamped" regime, and the "synchronized" regime for high scattering -characterized by a varying degree of nonequilibrium between the quantum-dot and reservoir states.Important differences to conventional lasers are found in the modulation response and the dynamics in optical injection and feedback setups. Common theoretical models and approaches used to describe these applications are shown to yield inaccurate predictions, especially in the "constant-reservoir" and "overdamped" dynamic regimes. An important consequence is that the amplitude-phase coupling in quantum-dot lasers, commonly described by the α-factor, differs from conventional descriptions due to the desynchronization of gain and refractive index. While the α-factor describes bifurcations of fixed points accurately, it fails in describing dynamic solutions and overestimates the extent of complex dynamics. The observed low sensitivity to optical perturbations in quantum-dot lasers can therefore be attributed partly to the charge-carrier nonequilibrium. Three quantum-dot laser models on different levels of sophistication are presented that can accurately describe the quantum-dot nonequilibrium dynamics.In the second part of the thesis, the performance of quantum-dot semiconductor optical amplifiers is investigated, and two types of applications unique to quantum-dots as active medium are discussed. The ground and excited states of the quantum-dots allow an ultra-broad-band amplification of optical data streams. Amplified signals on the ground-state frequencies are shown to generally exhibit higher quality than on the excited state, due to a lower sensitivity of the groundstate to carrier-density variations. Nevertheless the quantum-dot amplifier is found to allow effective amplification on both frequency ranges. Furthermore, a parameter range is identified that allows for a simultaneous amplification of data signals on the ground and excited state in a counter-propagating setup.The long microscopically polarization dephasing times in quantum-dots are found to enable quantum-coherent interactions on a macroscopic scale at room-temperature. By comparison with experiments, the occurrence of Rabi-oscillations by amplification of ultra-short pulses is demonstrated. Quantum-dot based devices could therefore be used for future applications based on quantum-coherent effects.

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Section: Amplitude-phase Coupling In Quantum-dot Lasersmentioning

confidence: 99%

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Lingnau

2015

Springer Theses

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“…The precise mode separation can only be obtained from the above-threshold analysis [16,17], but an analysis at the threshold [12,13] allows a good estimation. Thus, the results found at the threshold may be used to design the structure to be analyzed in the above-threshold regime.…”

Section: Design Of the Coupled Dbr Laser Cavitymentioning

confidence: 99%

“…On this concept, various cavity designs have been studied and realized as, e.g., the complex cavity injection grating (CCIG) [13][14][15][16], DFB with integrated feedback (IFB-DFB) [17] or single-mode cavity with feedback effects [18,19]. Furthermore, the modulation bandwidth extension can be obtained with the injection-locking of a laser to the optical signal of an external source (see, e.g., [20][21][22]).…”

Section: Introductionmentioning

confidence: 99%

Design and Analysis of Enhanced Modulation Response in Integrated Coupled Cavities DBR Lasers Using Photon-Photon Resonance

2016

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Abstract:In the last few decades, various solutions have been proposed to increase the modulation bandwidth and, consequently, the transmission bit-rate of semiconductor lasers. In this manuscript, we discuss a design procedure for a recently proposed laser cavity realized with the monolithic integration of two distributed Bragg reflector (DBR) lasers allowing one to extend the modulation bandwidth. Such an extension is obtained introducing in the dynamic response a photon-photon resonance (PPR) at a frequency higher than the modulation bandwidth of the corresponding single-section laser. Design guidelines will be proposed, and dynamic small and large signal simulations results, calculated using a finite difference traveling wave (FDTW) numerical simulator, will be discussed to confirm the design results. The effectiveness of the design procedure is verified in a structure with PPR frequency at 35 GHz allowing one to obtain an open eye diagram for a non-return-to-zero (NRZ) digital signal up to 80 GHz. Furthermore, the investigation of the rich dynamics of this structure shows that with proper bias conditions, it is possible to obtain also a tunable self-pulsating signal in a frequency range related to the PPR design.

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“…As a consequence of the relationship between differential gain and carrier density, cavity photons may be more efficiently modulated in a section subject to a lower biasing current [1]. While improving the modulation efficiency, the gain-lever effect is also observed to enhance the 3-dB modulation bandwidth [2]; such improvements achieved through the alteration of a laser's electrical biasing conditions are highly attractive, given that various other means of improving a laser's modulation characteristics involve external light sources (optical injection-locking) [3,4] or external feedback control mechanisms [5,6].…”

Section: Introductionmentioning

confidence: 99%

Modulation response of a long-cavity, gain-levered quantum-dot semiconductor laser

Pochet¹,

Usechak²,

Schmidt³

et al. 2014

Opt. Express

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Abstract:The gain-lever effect enhances the modulation efficiency of a semiconductor laser when compared to modulating the entire laser. This technique is investigated in a long-cavity multi-section quantum-dot laser where the length of the modulation section is varied to achieve 14:2, 15:1 and 0:16 gain-to-modulation section ratios. In this work, the gain-levered modulation configuration resulted in an increase in modulation efficiency by as much as 16 dB. This investigation also found that the 3-dB modulation bandwidth and modulation efficiency are dependent on the modulation section length of the device, indicating the existence of an optimal gain-to-modulation section ratio. The long cavity length of the multi-section laser yielded a distinctive case where characteristics of both the gain-lever effect and spatial effects are observed in the modulation response. Here, spatial effects within the cavity dominated the small-signal modulation response close to and above the cavity's free-spectral range frequency, whereas the gain-lever effect influenced the modulation response throughout the entirety of the response.

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Improving the Modulation Bandwidth in Semiconductor Lasers by Passive Feedback

Cited by 132 publications

References 17 publications

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Design and Analysis of Enhanced Modulation Response in Integrated Coupled Cavities DBR Lasers Using Photon-Photon Resonance

Modulation response of a long-cavity, gain-levered quantum-dot semiconductor laser

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