High-power ultrafast laser diodes

Pulse properties of external-cavity mode-locked semiconductor lasers

“…The maximum attainable bitrate in these systems is determined by the shortest temporal width and timing jitter of the pulses; hence, a thorough understanding of the underlying mechanisms is of crucial interest for future applications. In spite of the limited integrability of external-cavity mode-locked semiconductor lasers (ECMLLs), they are particularly interesting as optical sources for laboratory use, tunable both in wavelength and repetition rate [1] and for high power generation [2]. To date, most of the mode-locked semiconductor lasers generating pulses shorter than one picosecond are of the type of colliding-pulse mode-locking which are not tunable [3].…”

“…The saturation energy of SOA and ABS, determining the pulse shaping strength, have contributions from gain depletion (differential saturation) [7] and non-equilibrium processes [8]. Ultrafast processes are increasingly important when the pulsewidth reaches their characteristic sub-picosecond time scales, specially due to hot carrier thermalization [2]. Since ultrafast effects modify the saturation energies and, in turn, the shortening strength, they ultimately define the shortest attainable pulsewidth.…”

Picosecond pulses from wavelength-swept continuous-wave Fourier domain mode-locked lasers

“…In general, pulse energy can be increased using semiconductor-based master oscillator power amplifier systems. Whereas in case of single-spatial-mode semiconductor optical amplifiers (SOAs) the achievable pulse energies typically range from a few pJ to few tens of pJ 3,9 , higher energies become feasible using multispatial-mode semiconductor-based amplifiers like inverse bowtie SOAs 10 or tapered amplifiers [11][12][13][14] . Increased pulse energies can be achieved using the semiconductor-based eXtreme chirped pulse amplification concept 9 , where pulses are stretched temporally before amplification and the output energy of the recompressed pulse then exceeds the fundamental energy-storage limit of the semiconductor gain medium.…”

“…Compared with other gain media, the application of fully semiconductor-based laser sources can have many significant advantages owing to optimal compactness, robustness, cost-effectiveness, very-high wall-plug efficiency, simple current pumping, broadband gain bandwidth or spectral versatility. Since their first demonstration 2 , there has been great effort to improve the performance of ultrashort pulse generation with semiconductor lasers, reducing the pulse duration and increasing the output power 3,4 . Active-, passiveor colliding-pulse mode-locking techniques 5,6 were the prerequisite for the generation of few picosecond and subpicosecond pulses, considerably impeded due to non-linear phase changes associated with gain saturation 4 .…”

Quantum size effect on the electronic transitions of GaAs/AlGaAs dots under twisted light

“…These fields and heat or pressure have another disadvantage of limited time-scale which means that it is not possible to manipulate the particles in the quantum system because time duration between two pulses is not comparable to the time-scale of the particle. Fortunately, ultrafast technology in laser science give us the freedom to send out the electromagnetic field in nano-, pico-, femto-second time scale [14,15]. As a future technology, attosecond laser systems will enable us to investigate and analyze the ultrafast processes of quantum systems [16].…”