799 research outputs found
Self-Mixing Thin-Slice Solid-State Laser Metrology
This paper reviews the dynamic effect of thin-slice solid-state lasers subjected to frequency-shifted optical feedback, which led to the discovery of the self-mixing modulation effect, and its applications to quantum-noise-limited versatile laser metrology systems with extreme optical sensitivity
Experimental comparison of autodyne and heterodyne laser interferometry using a Nd:YVO4 microchip laser
Using a Nd:YVO4 microchip laser with a relaxation frequency in the megahertz
range, we have experimentally compared a heterodyne interferometer based on a
Michelson configuration with an autodyne interferometer based on the laser
optical feedback imaging (LOFI) method regarding their signal to noise ratios.
In the heterodyne configuration, the beating between the reference beam and the
signal beam is realized outside the laser cavity while in the autodyne
configuration, the wave beating takes place inside the laser cavity and the
relaxation oscillations of the laser intensity then play an important part. For
a given laser output power, object under investigation and detection noise
level, we have determined the amplification gain of the LOFI interferometer
compared to the heterodyne interferometer. LOFI interferometry is demonstrated
to show higher performances than heterodyne interferometry for a wide range of
laser power and detection level of noise. The experimental results are in good
agreement with the theoretical predictions
Nonlinear modification of the laser noise power spectrum induced by a frequency-shifted optical feedback
In this article, we study the non-linear coupling between the stationary
(i.e. the beating modulation signal) and transient (i.e. the laser quantum
noise) dynamics of a laser subjected to frequency shifted optical feedback. We
show how the noise power spectrum and more specifically the relaxation
oscillation frequency of the laser are modified under different optical
feedback condition. Specifically we study the influence of (i) the amount of
light returning to the laser cavity and (ii) the initial detuning between the
frequency shift and intrinsic relaxation frequency. The present work shows how
the relaxation frequency is related to the strength of the beating signal and
the shape of the noise power spectrum gives an image of the Transfer Modulation
Function (i.e. of the amplification gain) of the nonlinear-laser dynamics.The
theoretical predictions, confirmed by numerical resolutions, are in good
agreements with the experimental data.Comment: in Physical Review, American Physical Society (APS), 201
Spatio-temporal characterisation of a 100 kHz 24 W sub-3-cycle NOPCPA laser system
In recent years, OPCPA and NOPCPA laser systems have shown the potential to supersede Ti:sapphire plus post-compression based laser systems to drive next generation attosecond light sources via direct amplification of few-cycle pulses to high pulse energies at high repetition rates. In this paper, we present a sub 3-cycle, 100 kHz, 24 W NOPA laser system and characterise its spatio-temporal properties using the SEA-F-SPIDER technique. Our results underline the importance of spatio-temporal diagnostics for these emerging laser systems
Optical feedback effects on terahertz quantum cascade lasers: modelling and applications
Terahertz (THz) quantum cascade lasers (QCLs) are compact sources of radiation in the 1–5 THz range with significant potential for applications in sensing and imaging. Laser feedback interferometry (LFI) with THz QCLs is a technique utilizing the sensitivity of the QCL to the radiation reflected back into the laser cavity from an external target. We will discuss modelling techniques and explore the applications of LFI in biological tissue imaging and will show that the confocal nature of the QCL in LFI systems, with their innate capacity for depth sectioning, makes them suitable for skin diagnostics with the well-known advantages of more conventional confocal microscopes. A demonstration of discrimination of neoplasia from healthy tissue using a THz, LFI-based system in the context of melanoma is presented using a transgenic mouse model. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only
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