10 research outputs found
CW Emission and Self-Pulsing in a III-V/SiN Hybrid Laser With Narrow Band Mirror
We report on how external cavity III-V/SiN hybrid lasers operate in regimes of ultra-damped relaxation oscillations or in CW unstable dynamical regimes (self-pulsing or approaching turbulence) as a consequence of mirror dispersion, non-zero linewidth enhancement factor, and four-wave mixing in the gain medium. The impact of the dispersive mirror bandwidth and different mirror effective lengths on the laser tolerance to external optical feedback is also discussed
Cavity Light Bullets: 3D Localized Structures in a Nonlinear Optical Resonator
We consider the paraxial model for a nonlinear resonator with a saturable
absorber beyond the mean-field limit and develop a method to study the
modulational instabilities leading to pattern formation in all three spatial
dimensions. For achievable parametric domains we observe total radiation
confinement and the formation of 3D localised bright structures. At difference
from freely propagating light bullets, here the self-organization proceeds from
the resonator feedback, combined with diffraction and nonlinearity. Such
"cavity" light bullets can be independently excited and erased by appropriate
pulses, and once created, they endlessly travel the cavity roundtrip. Also, the
pulses can shift in the transverse direction, following external field
gradients.Comment: 4 pages, 3 figures, simulations files available at
http://www.ba.infn.it/~maggipin/PRLmovies.htm, submitted to Physical Review
Letters on 24 March 200
Nozaki-Bekki optical solitons
Recent years witnessed rapid progress of chip-scale integrated optical
frequency comb sources. Among them, two classes are particularly significant --
semiconductor Fabry-Per\'{o}t lasers and passive ring Kerr microresonators.
Here, we merge the two technologies in a ring semiconductor laser and
demonstrate a new paradigm for free-running soliton formation, called
Nozaki-Bekki soliton. These dissipative waveforms emerge in a family of
traveling localized dark pulses, known within the famed complex Ginzburg-Landau
equation. We show that Nozaki-Bekki solitons are structurally-stable in a ring
laser and form spontaneously with tuning of the laser bias -- eliminating the
need for an external optical pump. By combining conclusive experimental
findings and a complementary elaborate theoretical model, we reveal the salient
characteristics of these solitons and provide a guideline for their generation.
Beyond the fundamental soliton circulating inside the ring laser, we
demonstrate multisoliton states as well, verifying their localized nature and
offering an insight into formation of soliton crystals. Our results consolidate
a monolithic electrically-driven platform for direct soliton generation and
open a door for a new research field at the junction of laser multimode
dynamics and Kerr parametric processes
Threshold behaviour of optical frequency comb self-generation in an InAs/InGaAs quantum dot laser
We report on a significant reduction of both the radiofrequency beat note line width at 40.7 GHz and the integrated relative intensity noise of a 1 mm long edge-emitting monolithic Fabry–Perot InAs/InGaAs quantum dot semiconductor laser emitting from the ground state at 1250 nm by injection current control. For increasing injection currents, first an unlocked multi-mode behavior is observed and then, at a certain current above lasing threshold, self-locking of the longitudinal modes due to the internal non-linear effects occurs yielding a beat line width of 20 kHz (−3 dB) in contrast to tens of megahertz for lower injection currents. These results are confirmed by simulations
Nanoscale Displacement Sensing Based on Nonlinear Frequency Mixing in Quantum Cascade Lasers
Photo-generated metamaterials induce modulation of CW terahertz quantum cascade lasers
Periodic patterns of photo-excited carriers on a semiconductor surface profoundly modifies its effective permittivity, creating a stationary all-optical quasi-metallic metamaterial. Intriguingly, one can tailor its artificial birefringence to modulate with unprecedented degrees of freedom both the amplitude and phase of a quantum cascade laser (QCL) subject to optical feedback from such an anisotropic reflector. Here, we conceive and devise a reconfigurable photo-designed Terahertz (THz) modulator and exploit it in a proof-of-concept experiment to control the emission properties of THz QCLs. Photo-exciting sub-wavelength metastructures on silicon, we induce polarization-dependent changes in the intra-cavity THz field, that can be probed by monitoring the voltage across the QCL terminals. This inherently flexible approach promises groundbreaking impact on THz photonics applications, including THz phase modulators, fast switches, and active hyperbolic media