Institut National D'optique

Louis Desbiens

Yves Taillon

Pascal Deladurantaye

Brian W Baird

Vincent Roy

Marco Michele Sisto

Michel Jacob

Dany Lemieux

Mathieu Drolet

Claude Pare

Claude Paré

Pierre Laperle

François Brunet

David Gay

Francois Brunet

A laser system based on nonlinear pulse compression and a LMA optical fiber therefor are provided. The LMA optical fiber is configured to amplify seed light pulses and promote the onset of nonlinear spectral broadening. The LMA optical fiber includes a first section having constant core and cladding diameters and receiving and supporting propagation of the light pulses in multiple transversal modes. The first section is configured to suppress high order modes propagating therealong. The LMA optical fiber further includes a tapered second section receiving the fundamental mode from the first section, the core and cladding diameters increasing gradually along said second section so as to provide an adiabatic transition of the fundamental mode. The LMA optical fiber further includes an optional third section having constant core and cladding diameters. Dispersive compression of the light pulses outputted by the LMA optical fiber provides excellent beam quality and high peak powers.

Active LMA optical fiber and laser system using the same

A system and method generate laser pulses. Using the modulation signal from a pulse generation module, a seed laser diode generates seed light pulses in response to direct drive current modulation. The seed light pulses have a pulse duration longer than a target pulse duration and a spectral chirp. A compression module has dispersion characteristics over a broad spectral range. The pulse generation module is configured to adapt the modulation signal to tailor the spectral chirp of the seed light pulses in view of the dispersion characteristics of the compression module, such that propagation of the seed light pulses through the compression module compresses the seed pulses into output light pulses having the target pulse duration.

System and method for generating light pulses based on direct current  modulation of a seed laser diode

Method and system for emitting optical pulses in view of a desired output energy of the optical pulses and a variable external trigger signal, using a laser system having a seed laser oscillator optically coupled to one or more cascaded optical amplification stages. For each amplification stage, a plurality of sets of pump pulse parameters are provided, each associated with specific values of the output energy and the trigger period. Proper pumping parameters associated with the received desired value of the output energy and the trigger period of the received trigger signal are selected for each amplification stage, which is pumped accordingly before a seed optical pulse is launched through the system.

System and method for emitting optical pulses in view of a variable external trigger signal

A light stripper assembly for dissipating a residual optical pump power carried by a pump light propagating in an optical fiber component is provided. The optical fiber component includes a pump cladding surrounded by an outer cladding, the outer cladding being removed from the optical fiber component along a lengthwise segment thereof. The light stripper assembly includes a pump stripper disposed about the lengthwise segment and a heat-dissipation packaging structure thermally contacting the pump stripper. The pump stripper includes an input guiding region and a stripping region having refractive indices lower and higher than the refractive index at the outermost periphery of the pump cladding, respectively, so that the pump light is at least partially guided inside the pump cladding along the input guiding region and stripped from the pump cladding along the stripping region. The heat-dissipation packaging structure absorbs and dissipates the residual power stripped by the stripping region.

Dual-index optical pump stripper assembly

A method and device are provided for generating bursts of sub-pulses, preferably in the picosecond range. Seed pulses are first generated, and then phase modulated to spread their spectral profile to several time-dependent spectral components. The phase modulated seed pulses are then spectrally filtered to remove spectral components and retain only selected ones, creating gaps in the amplitude profile of the seed pulses which therefore form bursts of sub-pulses. Various parameters such as the modulation amplitude, the modulation frequency, the spectral characteristics of the filters and the overall amplitude of the seed pulses may be controlled to provide a great versatility and adaptability.

Device and method for generating bursts of picosecond optical sub-pulses

A circuit assembly controlling an optical system to generate optical pulses is provided. The optical system includes a seed light source optically coupled to an amplitude modulator. The circuit assembly includes a control circuit which generates a pulsed seed drive signal for driving the seed laser source, as well as logic signals defining successions of ON and OFF states and having a predetermined relative timing relationship. One or more of the logic signals is delayed by a corresponding programmable delay line to adjust the relative timing relationship between the logic signals. A logic gating module combines the logic signals according to one or more logical rule, thereby providing a modulator drive signal. Using this circuit assembly, the optical system outputs an optical pulse at each ON state of the modulator drive signal synchronized with the passage of one of the seed optical pulses through the amplitude modulator.

Circuit assembly for controlling an optical system to generate optical pulses and pulse bursts

A method for stabilizing an output of a pulsed laser system includes a directly modulated laser diode by mitigating the effect of switching transients on the temporal shape of the outputted pulses. The method includes controlling a pulse shaping signal to define, over time, processing and conditioning periods. During the processing periods, the pulse shaping signal has an amplitude profile tailored to produce the desired temporal shape of the output. Each conditioning period either immediately precedes or follows a processing period. During a given processing period, the amplitude profile of the pulse shaping signal is tailored so that the drive current of the laser diode is lower than its maximum value during the corresponding processing period, and is of the same order of magnitude as the laser threshold current of the laser diode. In this manner, the stability of the output during the corresponding processing period is improved.

Method for stablizing an output of a pulsed laser system using pulse shaping

Laser systems and methods for providing an output light beam having a target spatial pattern are provided. A light generating module generates an input light beam, whose spectral profile is then tailored by imposing thereon a controllable phase modulation. The obtained spectrally tailored light beam is dispersed, using at least one spatially-dispersive element to provide an output light beam having a spatial profile which is a function of the spectral profile of the spectrally tailored light beam, The phase modulation is selected in view of the spectral profile of the input light beam and of the dispersion characteristics of the at least one spatially-dispersive element so that the spatial pattern of the output light beam matches the target spatial pattern therefor.

System and method for the spatial tailoring of laser light using temporal phase modulation

Methods stabilize the output of a pulsed laser system using pulse shaping capabilities. In some embodiments, transient effects following a transition between a QCW regime and a pulse shaping regime are mitigated by ensuring that the average QCW optical power substantially corresponds to the average pulsed optical power outputted in a steady-state operation of the pulsed laser system in the pulse shaping regime. The QCW signal or the pulse shaping signal may be adapted for this purpose. In other embodiments, transient effects associated with non-process pulses emitted between series of consecutive process pulses are mitigated through the proper use of sequential pulse shaping.

Methods for stabilizing the output of a pulsed laser system having pulse shaping capabilities

A pulsed fiber laser generating light pulses in the picosecond range has an adjustable pulsewidth. The fiber laser includes a figure-of-eight type laser cavity, preferably of polarization-maintaining optical fiber, defining reciprocal and non-reciprocal loops. A gain medium is disposed asymmetrically in the reciprocal loop, at a position therealong favoring coupling of light in the propagation direction of the non-reciprocal loop. A pump source is coupled to the reciprocal loop to inject pump light into the gain medium. The laser cavity is designed so that changing the pump power will directly affect the pulsewidth of the generated light pulses, providing a useful control mechanism of the pulsewidth.

Adjustable pulsewidth picosecond fiber laser

High power optical pulses generating methods and laser oscillators are provided. A light generating module generates seed optical pulses having predetermined optical characteristics. A spectrum tailoring module is then used to tailor the spectral profile of the optical pulses. The spectral tailoring module includes a phase modulator which imposes a time-dependent phase variation on the optical pulses. The activation of the phase modulator is synchronized with the passage of the optical pulse therethough, thereby efficiently reducing the RF power necessary to operate the device.

Spectrally tailored pulsed fiber laser oscillator

There is provided a long-band rare-earth-doped optical amplifier and method for amplifying an optical signal. The optical amplifier has a pre-, a mid- and a post-amplification stage. Only the mid-amplification stage is pumped with a pump light source. The other two are pumped using Amplified Spontaneous Emission (ASE) generated in the mid-amplification stage. An optical coupling device is used to couple the three amplification stages together and to split the ASE generated in the mid-amplification stage and available at one end of the mid-amplification stage. One part of the split ASE is used to pump the pre-amplification stage while the other part is used to pump the post-amplification stage.

Multi-stage long-band optical amplifier with ASE re-use

There is provided a parabolic pulse amplifier for amplifying a pulse light signal. The amplifier comprises an ytterbium-doped amplification waveguide pumped using a pump source with a pump central wavelength substantially offset from the absorption transition peak wavelength. The pump wavelength is selected such that the absorption coefficient of pump light and the gain coefficient of the signal are substantially equal in the amplification waveguide such that the amplification gain is distributed substantially uniformly along the amplification waveguide.

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St-Augustin-de-Desmaures, Canada

Louis Desbiens