22,116 research outputs found
Dynamic modal analysis of monolithic mode-locked semiconductor lasers
We analyze the advantages and applicability limits of the mode-coupling approach to active, passive, hybrid, and harmonic mode-locking in diode lasers. A simple, computationally efficient numerical model is proposed and applied to several traditional and advanced laser constructions and regimes, including high-frequency pulse emission by symmetric and asymmetric colliding pulse mode-locking, and locking properties of hybrid modelocked Fabry–Perot and distributed Bragg reflector lasers
Injection locking of an electro-optomechanical device
The techniques of cavity optomechanics have enabled significant achievements
in precision sensing, including the detection of gravitational waves and the
cooling of mechanical systems to their quantum ground state. Recently, the
inherent non-linearity in the optomechanical interaction has been harnessed to
explore synchronization effects, including the spontaneous locking of an
oscillator to a reference injection signal delivered via the optical field.
Here, we present the first demonstration of a radiation-pressure driven
optomechanical system locking to an inertial drive, with actuation provided by
an integrated electrical interface. We use the injection signal to suppress
drift in the optomechanical oscillation frequency, strongly reducing phase
noise by over 55 dBc/Hz at 2 Hz offset. We further employ the injection tone to
tune the oscillation frequency by more than 2 million times its narrowed
linewidth. In addition, we uncover previously unreported synchronization
dynamics, enabled by the independence of the inertial drive from the optical
drive field. Finally, we show that our approach may enable control of the
optomechanical gain competition between different mechanical modes of a single
resonator. The electrical interface allows enhanced scalability for future
applications involving arrays of injection-locked precision sensors.Comment: Main text: 10 pages, 7 figures. Supplementary Information: 5 pages, 4
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Phase-locking in Multi-Frequency Brillouin Oscillator via Four Wave Mixing
Stimulated Brillouin scattering (SBS) and Kerr-nonlinear four wave-mixing
(FWM) are among the most important and widely studied nonlinear effects in
optical fibres. At high powers SBS can be cascaded producing multiple Stokes
waves spaced by the Brillouin frequency shift. Here, we investigate the complex
nonlinear interaction of the cascade of Stokes waves, generated in a
Fabry-Perot chalcogenide fibre resonator through the combined action of SBS and
FWM. We demonstrate the existence of parameter regimes, in which pump and
Stokes waves attain a phase-locked steady state. Real-time measurements of 40ps
pulses with 8GHz repetition rate are presented, confirming short-and long-term
stability. Numerical simulations qualitatively agree with experiments and show
the significance of FWM in phase-locking of pump and Stokes waves. Our findings
can be applied for the design of novel picosecond pulse sources with GHz
repetition rate for optical communication systems
Direct observation of magnetization dynamics generated by nano-contact spin-torque vortex oscillators
Time-resolved scanning Kerr microscopy has been used to directly image the
magnetization dynamics of nano-contact (NC) spin-torque vortex oscillators
(STVOs) when phase-locked to an injected microwave (RF) current. The Kerr
images reveal free layer magnetization dynamics that extend outside the NC
footprint, where they cannot be detected electrically, but which are crucial to
phase-lock STVOs that share common magnetic layers. For a single NC, dynamics
were observed not only when the STVO frequency was fully locked to that of the
RF current, but also for a partially locked state characterized by periodic
changes in the core trajectory at the RF frequency. For a pair of NCs, images
reveal the spatial character of dynamics that electrical measurements show to
have enhanced amplitude and reduced linewidth. Insight gained from these images
may improve understanding of the conditions required for mutual phase-locking
of multiple STVOs, and hence enhanced microwave power emission.Comment: 10 pages, 3 figure
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