37 research outputs found
Intensity and phase noise correlations in a dual-frequency VECSEL operating at telecom wavelength
The amplitude and phase noises of a dual-frequency vertical-external-cavity
surface-emitting laser (DF-VECSEL) operating at telecom wavelength are
theoretically and experimentally investigated in detail. In particular, the
spectral behavior of the correlation between the intensity noises of the two
modes of the DF-VECSEL is measured. Moreover, the correlation between the phase
noise of the radio-frequency (RF) beatnote generated by optical mixing of the
two laser modes with the intensity noises of the two modes is investigated. All
these spectral behaviors of noise correlations are analyzed for two different
values of the nonlinear coupling between the laser modes. We find that to
describe the spectral behavior of noise correlations between the laser modes,
it is of utmost importance to have a precise knowledge about the spectral
behavior of the pump noise, which is the dominant source of noise in the
frequency range of our interest (10 kHz to 35 MHz). Moreover, it is found that
the noise correlation also depends on how the spatially separated laser modes
of the DF-VECSEL intercept the noise from a multi-mode fiber-coupled laser
diode used for pumping both the laser modes. To this aim, a specific experiment
is reported, which aims at measuring the correlations between different spatial
regions of the pump beam. The experimental results are in excellent agreement
with a theoretical model based on modified rate equations
Recovering the dynamics of optical frequency combs from phase-amplitude noise correlations measurements
Controlling the noise properties of optical frequency combs (OFC) is of great
importance as most OFC-based precision measurements are limited by their
intrinsic stability. It has been found that OFC noise manifests itself as
fluctuations of only a few global parameters, which indicates strong
correlations between the fluctuations of individual frequency lines. However,
the physical processes underneath such correlations are still not completely
understood. We introduce a novel measurement scheme that allows us to measure
simultaneously and in real time the whole Fourier spectrum of phase and
amplitude fluctuations of the OFC field as well as its amplitude-phase
correlations in many frequency bands spanning the laser spectrum. This enables
us to determine the full quadrature covariance matrices in the frequency band
mode basis, and this for various Fourier frequencies, to find their principal
modes in time and frequency domain, and to associate them with global physical
parameters
Phase Noise of the Radio Frequency (RF) Beatnote Generated by a Dual-Frequency VECSEL
We analyze, both theoretically and experimentally, the phase noise of the
radio frequency (RF) beatnote generated by optical mixing of two orthogonally
polarized modes in an optically pumped dual-frequency Vertical External Cavity
Surface Emitting Laser (VECSEL). The characteristics of the RF phase noise
within the frequency range of 10 kHz - 50 MHz are investigated for three
different nonlinear coupling strengths between the two lasing modes. In the
theoretical model, we consider two different physical mechanisms responsible
for the RF phase noise. In the low frequency domain (typically below 500 kHz),
the dominant contribution to the RF phase noise is shown to come from the
thermal fluctuations of the semicondutor active medium induced by pump
intensity fluctuations. However, in the higher frequency domain (typically
above 500 kHz), the main source of RF phase noise is shown to be the pump
intensity fluctuations which are transfered to the intensity noises of the two
lasing modes and then to the phase noise via the large Henry factor of the
semiconductor gain medium. For this latter mechanism, the nonlinear coupling
strength between the two lasing modes is shown to play an important role in the
value of the RF phase noise. All experimental results are shown to be in good
agreement with theory
Experimental and theoretical studies of a dual-frequency laser free from anti-phase noise
International audienceStrong reduction of the anti-phase intensity noise is shown in a two-polarization dual-frequency solid-state laser. The spectral behavior of the intensity noise correlations between the two orthogonally polarized modes is investigated, both experimentally and theoretically
Transient subdiffusion via disordered quantum walks
Transport phenomena play a crucial role in modern physics and applied sciences. Examples include thedissipation of energy across a large system, the distribution of quantum information in optical networks, andthe timely modeling of spreading diseases. In this work we experimentally prove the feasibility of disorderedquantum walks to realize a quantum simulator that is able to model general transient subdiffusive phenomena,exhibiting a sublinear spreading in space over time. Our experiment simulates such phenomena by means ofa finely controlled insertion of various levels of disorder during the evolution of the walker, enabled by theunique flexibility of our setup. This allows us to explore the full range of subdiffusive behaviors, ranging fromanomalous Anderson-like localization to normal diffusion for all experimentally accessible step numbers
Experimental demonstration of a dual-frequency laser free from anti-phase noise
A reduction of more than 20 dB of the intensity noise at the anti-phase
relaxation oscillation frequency is experimentally demonstrated in a
two-polarization dual-frequency solid-state laser without any optical or
electronic feedback loop. Such a behavior is inherently obtained by aligning
the two orthogonally polarized oscillating modes with the crystallographic axes
of a (100)-cut neodymium-doped yttrium aluminum garnet active medium. The
anti-phase noise level is shown to increase as soon as one departs from this
peculiar configuration, evidencing the predominant role of the nonlinear
coupling constant. This experimental demonstration opens new perspectives on
the design and realization of extremely low noise dual-frequency solid-state
lasers