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This paper presents a comprehensive overview of the underlying physics of optical injection mechanisms in lasers highlighting the determining influence of important parameters as the injection strength, the frequency detuning and the free running oscillation frequency of the interacting lasers. The paper particularly sheds light on the different properties exhibited by inter-band diode lasers and...
Quantum cascade lasers emitting at λ∼5 µm based on different active region designs are investigated. Using lattice-matched GaInAs/AlInAs on InP substrates the maximum peak optical power as well as the maximum pulsed-mode operating temperature is enhanced by incorporating AlAs blocking barriers together with strain-compensating InAs layers into the active regions. Further improvement is achieved by...
Passively mode-locked two-section quantum-dot monolithic semiconductor lasers are promising optical pulse sources for nonlinear medical imaging and communication applications. Their advantages are their compactness, ease of operation and high efficiency compared to solid state lasers. Quantum-dots (QD) incorporated as the active medium in a diode laser offer peculiar advantages like broad gain bandwidth...
The correlations of photon arrival times in light beams are of fundamental physical interest as they reveal the nature of the photon emission process. Recently, the analysis of ultra-fast photon correlations in temporally incoherent light has been achieved with a modified version of a Hanbury-Brown Twiss interferometer [1]. We utilize this technique to investigate the degree of second order coherence...
The emission-state dynamics of a strongly spectrally inhomogeneously broadened two-section InAs/InGaAs quantumdot (QD) laser are experimentally investigated by exploiting a resistor-SEEDconfiguration and by reverse-biasing the absorber. By joining these operation regimes for the first time, a combined and complete understanding of the two-state carrier dynamics including a photon pumping process in...
A new functionality of a quantum dot self-electro-optical absorber is demonstrated. External resistor tuning of a quantum dot absorber via the quantum-confined Stark effect in a strongly chirped broadband two-section quantum dot laser configuration allows tuning from the modelocked ground state emission at 1270 nm to the excited state emission at 1207 nm with decreasing resistance.
In low coherent light interferometry (OCT) broad bandwidth light sources are required to achieve high axial resolution. Here superluminescent light emitting diodes (SLEDs) utilizing quantum dot (QD) gain materials are promising devices as they unify large spectral bandwidths with high power at desired emission wavelengths. However, due to the spectral dot dynamics, dips in the optical spectrum occur...
The authors report on the existence and interaction of the ground state (GS) and excited state (ES) emission in continuous wave (CW) and large signal pulsed operation at three temperatures (20degC, 40degC, 50degC). Good agreement of the model with the experiment regarding the power-current and the switch-on dynamics allows the model the extraction of the determining physical parameters and may be...
The mode-locking beat stability of a monolithic mode-locked quantum-dot laser is improved by an auxiliary mode-comb. A tenfold enhancement of the beating carrier red-shift and a substantial improvement of the RMS timing jitter is achieved.
A monolithic semiconductor ring laser (SRL) is demonstrated as a fully all-optical flip-flop that can be triggered by optical pulses of 400 ps duration, showing 130 ps response time.
We present calculations concerning the generation of terahertz waves by difference frequency generation (DFG) using mid-infrared (MIR) radiation. We investigate phase matching conditions using a waveguide design for semiconductor materials like GaAs, GaP, InP or InAs which are transparent for both MIR and THz radiation and exhibit a large nonlinear coefficient.
A monolithic semiconductor ring laser (SRL) is demonstrated to operate as an all-optical flip-flop that is triggered by optical pulses of 400 ps and 5 ps duration, showing a response time of 130 ps.
Broad-area vertical-cavity surface-emitting laser (BA-VCSELs) can be made to emit spatially incoherent light by driving them with strong current pulses, as we demonstrated in [1]. This state of incoherent emission is of fundamental importance as it is not readily observable in semiconductor lasers. It can be useful in, for example, projection systems where a low degree of spatial coherence might help...
Round-robin measurements on the linewidth enhancement factor are carried out in many laboratories participating to EU COST 288 Action. Up to 7 different techniques are applied to DFB, VCSELs, QCL, and QD lasers, and results are compared.
In this paper, we present a joint theoretical and experimental investigation on the effect of frequency-filtered and spatially shaped feedback on the emission of a multi-transverse mode VCSEL. We have built for this purpose a delay-differential model which associates a cold-cavity mode expansion to the spin-flip formalism, thereby permitting to track simultaneously the modal and the polarization dynamics...
The linewidth enhancement factor (or alpha parameter) describes the coupling of amplitude and phase in a semiconductor laser. In quantum cascade lasers, the self-mixing effect necessary for single mode operation, is usually realized by using a distributed feedback grating. Such a grating is optimized to work for a special wavelength at a fixed temperature. If the temperature of the laser device differs...
Round-robin measurements on the linewidth enhancement factor are carried out within several laboratories participating to EU COST 288 action. The alpha-factor is measured by applying up to 7 different techniques. The obtained results are compared.
We study the spectral and dynamical behavior of two identical, mutually delay-coupled semiconductor lasers. We concentrate on the short coupling-time regime where the number of basic states of the system, the compound laser modes (CLMs), is small so that their individual behavior can be studied both experimentally and theoretically. As such it constitutes a prototype example of delay-coupled laser...
This study investigates a 50 mum-aperture broad-area vertical-cavity surface-emitting laser (BA-VCSEL) and studied its temporally and spatially resolved emission behaviour. For this, an intensified CCD-camera is employed with 300 ps shutter time, with which events of the BA-VCSEL's emission in quasi-cw operation is observed. The BA-VCSEL is pumped with 100 mus long current pulses with a repetition...
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