Strong optical injection-locked semiconductor lasers demonstrating &gt; 100-GHz resonance frequencies and 80-GHz intrinsic bandwidths

Lau, E.K.; Zhao, Xiaoxue; Sung, Hyuk-Kee; Parekh, Devang; Chang-Hasnain, Connie J.; Wu, M.C.

doi:10.1364/oe.16.006609

Cited by 185 publications

(97 citation statements)

References 16 publications

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“…For this application, the power of the master laser can be much lower than that of the slave laser, allowing for the realization of high-power laser devices with extremely low linewidth [LIU02a]. Furthermore, the modulation bandwidth of laser devices was shown to be greatly increased by an appropriate injection setup [JIN06,TER08a,LAU09a], with bandwidths exceeding 100 GHz [LAU08a].…”

Section: Quantum-dot Laser Dynamicsmentioning

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: Quantum-dot Laser Dynamicsmentioning

confidence: 99%

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Lingnau

2015

Springer Theses

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“…Our method can suppress the chirp via injection locking and, at the same time, can improve the extinction ratio by destructively interfering the modulated signal with a small portion of the master laser, thereby mitigating two main limitations associated with the use of directly-modulated lasers for low cost OOK communications. Finally, injection locking can significantly enhance the laser modulation bandwidth -e.g., in [7] a 3-dB bandwidth of 80 GHz was achieved. This would allow our scheme to operate at up to 160 Gbaud.…”

Section: Discussionmentioning

confidence: 95%

QAM Synthesis by Direct Modulation of Semiconductor Lasers under Injection Locking

Slavı́k

Kakande

Phelan

et al. 2013

Optical Fiber Communication Conference/National Fiber Optic Engineers Conference 2013

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Abstract:A new scheme for direct synthesis of QAM (4,16,64,..) from binary RF data streams is suggested and tested by generating 10 Gbaud QPSK. Current semiconductor lasers should allow for operation up to 160 Gbaud.OCIS codes: (060.2340) Fiber optics components; (060.2380) Fiber optics sources and detectors IntroductionCoherent optical communications allows for better resilience to transmission-related linear and nonlinear impairments (e.g., using binary phase shift keying, BPSK) and/or for increased capacity via the transmission of several bits per symbol (e.g., QPSK, 16 QAM and higher). For these modulation formats, which exploit modulation of phase, direct modulation of the signaling laser is generally not possible due to the high chirp associated with such a modulation approach. Instead, an external IQ modulator is typically used, made from materials such as LiNbO 3 or InP. Although this approach clearly works well it brings several drawbacks: (i) a relatively high cost; (ii) significant insertion loss and limited optical power handling; (iii) the need for high drive voltage RF booster amplifiers; and (iv), a typical IQ modulator requires the processing (division into I and Q) and associated multiplexing of multiple high-speed binary electronic data signals, resulting in increased power loss and power consumption, noise and nonlinearity (which is particularly detrimental when the I and Q data streams have more than two levels, e.g., for 16-QAM, each has 4 levels). This last feature can be mitigated by using more complicated modulators with multiple electrical inputs and multiplexing in the optical domain [1], however, this comes at the cost of a higher optical insertion loss which in turn compromises the achievable OSNR (a critical issue when working with advanced modulation format signals).Here, we propose a new solution that simultaneously avoids all four issues associated with the use of external IQ modulators. It is based on ultralow chirp direct modulation of injection-locked (IL) semiconductor lasers followed by coherent superposition and coherent carrier suppression of their output. We show experimental results for BPSK and QPSK modulation, although it is straightforward to extend the basic concept to 16 QAM and higher modulation formats. We note that several techniques have previously been reported for constant-envelope modulation (e.g. BPSK, QPSK) based on direct laser or SOA based phase modulation [2] [3] [4], with some of these incorporating injection-locking [4]. However, in our opinion, these schemes cannot be straightforwardly extended to higher modulation formats (e.g. 16 QAM), offer limited performance and/or are applicable only to RZ formats.

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“…In order to investigate the influence of periodic modulation, it is crucial to previously understand the characteristic time scales of the chaotic dynamics induced by optical injection. In the parameter region where RWs occur the main characteristic time scale is the laser relaxation oscillation frequency, which in the solitary laser increases linearly with √ μ − μ th , while in the optically injected laser it also depends on the injection parameters [35,36]. Figure 2 presents typical examples of the power spectral density (PSD) and the corresponding intensity time trace, for two values of the laser bias current, μ 0 = 1.8 and 2.4, and two values of the injection detuning, ν = 0.22 GHz and −0.24 GHz.…”

Section: A Influence Of Optical Noise In the Occurrence Of Rogue Wavesmentioning

confidence: 99%

Controlling the likelihood of rogue waves in an optically injected semiconductor laser via direct current modulation

et al. 2014

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Extreme and rare events are nowadays the object of intensive research. Rogue waves are extreme waves that appear suddenly in many natural systems, even in apparently calm situations. Here we study numerically the rogue wave dynamics in an optically injected semiconductor laser with external periodic forcing that is implemented via direct modulation of the laser pump current. In the region of optical injection parameters where the laser intensity is chaotic and occasional ultrahigh pulses occur, our aim is to control the system by applying a weak modulation. We find that for an adequate range of frequency and amplitude parameters, the modulation can completely suppress the extreme pulses. We also show that the interplay between modulation and an external source of noise can significantly modify their probability of occurrence. These results can motivate a range of experimental and theoretical investigations in other natural systems.

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Strong optical injection-locked semiconductor lasers demonstrating > 100-GHz resonance frequencies and 80-GHz intrinsic bandwidths

Cited by 185 publications

References 16 publications

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

QAM Synthesis by Direct Modulation of Semiconductor Lasers under Injection Locking

Controlling the likelihood of rogue waves in an optically injected semiconductor laser via direct current modulation

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