Search results for "Q-switching"
showing 9 items of 29 documents
Transform-limited pulses generated by an actively Q-switched distributed fiber laser.
2008
A single-mode, transform-limited, actively Q-switched distributed-feedback fiber laser is presented, based on a new in-line acoustic pulse generator. Our technique permits a continuous adjustment of the repetition rate that modulates the Q factor of the cavity. Optical pulses of 800 mW peak power, 32 ns temporal width, and up to 20 kHz repetition rates were obtained. The measured linewidth demonstrates that these pulses are transform limited: 6 MHz for a train of pulses of 10 kHz repetition rate, 80 ns temporal width, and 60 mW peak power. Efficient excitation of spontaneous Brillouin scattering is demonstrated.
Q switching and mode locking pulse generation from an all-fiber ring laser by intermodal acousto-optic bandpass modulation
2018
Q-switched and mode-locked (QML) pulse generation from an all-fiber ring laser based on intermodal acousto-optic bandpass modulation is reported. The modulator relies on full-acousto-optic mode re-coupling cycle induced by a standing flexural acoustic wave, with a transmission response that is controlled by amplitude modulation of the acoustic wave signal. The Q factor of the cavity is controlled by a rectangular pulse wave with variable frequency and duty cycle, whereas mode locking is achieved by amplitude modulation derived from a standing flexural acoustic wave. The best QML pulses were obtained at 0.5 kHz repetition rate, with a pump power of 549.2 mW, at the optical wavelength of 1568…
Enhanced supercontinuum generation in the nanosecond pump regime using specialty microstructured fibers
2009
Several alternatives have been investigated to achieve enhanced supercontinuum generation in the nanosecond pump regime using specialty silica-based microstructured optical fibers (MOFs). Among these alternatives we can point out the use of (a) MOF tapers, (b) highly Ge-doped core Y-shaped MOF and (c) Er-doped MOF. These specialty MOFs provide either an increased material nonlinear response or a rather small effective area, at the same time that the dispersion characteristics are adjusted to work at different excitation conditions. In our experiments, we have been using either a Q-switched Nd:YAG laser (10 Hz repetition rate) or an Yb-doped fiber laser (2 kHz repetition rate), both emitting…
Supercontinuum Q-switched Yb fiber laser using an intracavity microstructured fiber
2009
We report on an intracavity configuration for supercontinuum generation in a Q-switched Yb fiber laser. The supercontinuum laser includes a section of microstructured fiber within the Q-switched laser cavity. With 380 mW of pump power, the supercontinuum laser can emit broadband pulses of 6 microJ energy and 10 ns temporal width, at repetition rates from few hertz up to 2 kHz. The supercontinuum spectrum spans over a wavelength range in excess of 1.4 microm.
Optical kerr effect in the strong field regime
2013
The optical Kerr response of hydrogen atom submitted to a strong and short near infrared laser pulse excitation is studied by solving the full 3D time-dependent Schro¨dinger equation. The nonlinear polarization evaluated at the driving field frequency is compared to the canonical expression derived from perturbation theory. A discrepancy between the two models is observed at large intensity affecting the nonlinear propagation of short and intense laser pulses.
Actively Q-switched and modelocked all-fiber lasers
2010
Here we demonstrate active mode-locking (ML) and doubly-active Q-switching mode-locking (QML) of erbium-doped strictly all-fiber lasers. The active ML mechanism relies in the acoustooptic superlattice modulation (AOSLM) effect induced when longitudinal acoustic waves are launched along a fiber Bragg grating. In both regimes - ML as well as QML - we focus on the laser behavior when the AOSLM is driven by traveling acoustic waves, and next we compare these results with those obtained when the AOSLM is driven by standing acoustic waves. In the ML regime, optical pulses were obtained of 530 mW peak power, 700 ps temporal width, at a repetition rate of 4.1 MHz. On the other hand, in the QML regi…
An experimental analysis of self-Q-switching via stimulated Brillouin scattering in an ytterbium doped fiber laser
2013
An experimental study of self-Q-switching (SQS) in an ytterbium doped fiber laser (YDFL) arranged using a twin-core GTWave assembly is reported. The main mechanisms that initiate, amplify, and limit SQS pulses in amplitude are revealed to be stimulated Brillouin and Raman scattering (SBS/SRS) and Yb3+ amplified spontaneous emission. The parameters featuring SQS oscillation in terms of efficiency and stability of pulsing are found to be intra-cavity loss and feedback strength. An analysis of the YDFL SQS regime?s features?pulsing time series, optical and RF spectra, amplitude and timing jitter?is provided for the two experimental situations: (i) when SQS pulsing stochastically intermits with…
Pulse timing effects in bulk Er/Yb codoped diode-pumped eyesafe lasers
2007
In this work, diode-pumping with appropriately modulated pulses is used to expose subtle input / output pulse-timing characteristics of Er3+ /Yb3+ systems, study their relation to laser efficiency and demonstrate some unique laser-pulse timing behavior. Er+3/Yb+3 codoped glass and YAG laser-host materials with similar concentrations (optimized for eyesafe emission in the 1.6-mum region) were studied in the same diode-pumped setup, in similar resonator configurations and analogous operating conditions.
Supercontinuum Generation and Intermodal Four-Wave Mixing in a Step-Index Few-Mode Fibre
2019
International audience; The complex spatiotemporal dynamics of nonlinear light propagation in multimode fibers (MMFs) has recently witnessed a renewed interest because of their experimental realization in emerging key areas of laser physics and fiber optics [1]. Specifically, MMFs have a number of linear and nonlinear optical properties that make them very attractive to investigate new spatiotemporal effects fundamentally different from standard single-mode fibers. These include the observation of multimode solitons [2], intermodal four-wave mixing (FWM) [3], geometric parametric instabilities [4], spatial beam self-cleaning [5], and the generation of supercontinuum (SC) light when pumping …