Abstract: A bulk compressor for use in a chirped pulse amplification system (CPA) comprising a tunable pulse stretcher and an amplifier is provided. The bulk compressor includes a mounting block formed as a monolithic structure and made of solid material. The mounting block may define a plurality of mounting surfaces each forming a collar surrounding a light passage. Optical components are mounted on the mounting block in a fixed mutual spatial relationship, each optical component having a front face having a peripheral portion mounted in direct contact with the collar formed by a respective one of the mounting surfaces. The bulk compressor may be provided as a stand-alone component, a part of a stretcher-compressor pair or a full CPA system, and may be used in a method for amplifying input optical pulses.

Abstract: Methods and systems enabling the real-time monitoring of a light-induced procedure in a biological medium, and/or the acquisition of information related to this biological medium are provided. In some implementations, the light beam used for the procedure is modulated at a modulation frequency selected in view of the photoacoustic frequency response associated with the procedure. The photoacoustic feedback signal from the medium during the procedure is then monitored. This monitoring may involve filtering the photoacoustic feedback signal around the selected feedback modulation frequency. Ratiometric comparisons of the contribution of different frequencies to the photoacoustic feedback signal are also considered.

Abstract: Methods and systems for the controlled generation of bubbles in a medium having a liquid phase are generally provided. Laser pulses having a time-dependent pulse parameter controllable over their duration are generated. The medium is irradiated with the laser pulses with a radiant exposure sufficient to initiate microcavitation within the medium during each laser pulse. The time-dependent pulse parameter of each laser pulse is controlled according to a generally positive variation over the pulse duration such that the medium absorbs a greater quantity of energy from the laser pulse at an end of the pulse duration than at a beginning thereof. Such methods and systems may be used for various applications such as biology, medicine or material processing.

Abstract: A bulk compressor for use in a chirped pulse amplification system (CPA) comprising a tunable pulse stretcher and an amplifier is provided. The bulk compressor includes a mounting block formed as a monolithic structure and made of solid material. The mounting block may define a plurality of mounting surfaces each forming a collar surrounding a light passage. Optical components are mounted on the mounting block in a fixed mutual spatial relationship, each optical component having a front face having a peripheral portion mounted in direct contact with the collar formed by a respective one of the mounting surfaces. The bulk compressor may be provided as a stand-alone component, a part of a stretcher-compressor pair or a full CPA system, and may be used in a method for amplifying input optical pulses.

Abstract: Methods and systems enabling the real-time monitoring of a light-induced procedure in a biological medium, and/or the acquisition of information related to this biological medium are provided. In some implementations, the light beam used for the procedure is modulated at a modulation frequency selected in view of the photoacoustic frequency response associated with the procedure. The photoacoustic feedback signal from the medium during the procedure is then monitored. This monitoring may involve filtering the photoacoustic feedback signal around the selected feedback modulation frequency. Ratiometric comparisons of the contribution of different frequencies to the photoacoustic feedback signal are also considered.

Abstract: Methods and systems for the controlled generation of bubbles in a medium having a liquid phase are generally provided. Laser pulses having a time-dependent pulse parameter controllable over their duration are generated. The medium is irradiated with the laser pulses with a radiant exposure sufficient to initiate microcavitation within the medium during each laser pulse. The time-dependent pulse parameter of each laser pulse is controlled according to a generally positive variation over the pulse duration such that the medium absorbs a greater quantity of energy from the laser pulse at an end of the pulse duration than at a beginning thereof. Such methods and systems may be used for various applications such as biology, medicine or material processing.

Abstract: Methods and systems for the controlled generation of microcavitation bubbles in a medium having a liquid phase are generally provided. Laser pulses having a time-dependent pulse parameter controllable over their duration are generated. The medium is irradiated with the laser pulses with a radiant exposure sufficient to initiate microcavitation within the medium during each laser pulse. The time-dependent pulse parameter of each laser pulse is controlled according to a generally positive variation over the pulse duration such that the medium absorbs a greater quantity of energy from the laser pulse at an end of the pulse duration than at a beginning thereof. Such methods and systems may be used for various applications such as biology, medicine or material processing.

Abstract: An optical fiber for use in a Coherent Anti-Stokes Raman Scattering (CARS) endoscope, comprising a core guiding lightwaves at a pump wavelength and at a Stokes wavelength, the core being single-mode at both wavelengths. The core is surrounded by cladding layers, including an inner cladding layer, a trench cladding layer, an intermediate cladding layer and an outer cladding layer. The refractive index of the trench cladding layer is lower than those of both neighboring cladding layers so as to define a trench in the radial refractive-index profile. The bending losses of the fundamental LP01 mode of the fiber at the Stokes wavelength are limited while maintaining high confinement losses for the higher-order LP11 mode of the fiber at the pump wavelength. The combination of the intermediate and outer cladding layers forms a multimode waveguide for guiding a collected CARS signal generated by an object or medium probed with the endoscope.

Abstract: 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.

Abstract: An optical fiber for use in a Coherent Anti-Stokes Raman Scattering (CARS) endoscope, comprising a core guiding lightwaves at a pump wavelength and at a Stokes wavelength, the core being single-mode at both wavelengths. The core is surrounded by cladding layers, including an inner cladding layer, a trench cladding layer, an intermediate cladding layer and an outer cladding layer. The refractive index of the trench cladding layer is lower than those of both neighboring cladding layers so as to define a trench in the radial refractive-index profile. The bending losses of the fundamental LP01 mode of the fiber at the Stokes wavelength are limited while maintaining high confinement losses for the higher-order LP11 mode of the fiber at the pump wavelength. The combination of the intermediate and outer cladding layers forms a multimode waveguide for guiding a collected CARS signal generated by an object or medium probed with the endoscope.

Abstract: A digital pulse shaping module provides a digital waveform such as a pulse shape, gating or a synchronizing digital signal for use with a pulsed laser oscillator. The digital pulse shaping module includes a waveform data generator that generates N-bit words having a number N of bits. A serializer is further provided to receive the N-bit words from the waveform data generator and outputs each bit individually in a series of bits corresponding to the digital waveform. The digital pulse shaping module further includes a delay module that provides a fine delay in the outputting of the bits by the serializer. This fine delay corresponds to a number of bits smaller than N, impacting on the timing of the outputted signal at the bit level. A pulse shaping generator has a plurality of digital pulse shaping modules.

Abstract: A tunable pulsed laser source comprising a seed source adapted to generate a seed signal and an optical circulator. The optical circulator includes a first port coupled to the seed source, a second port, and a third port. The laser source also includes an amplitude modulator characterized by a first side and a second side. The first side is coupled to the second port of the optical circulator. The laser source further includes a first optical amplifier characterized by an input end and a reflective end including a spectral-domain reflectance filter. The input end is coupled to the second side of the amplitude modulator. Moreover, the laser source includes a second optical amplifier coupled to the third port of the optical circulator.

Abstract: 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.

Abstract: 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.

Abstract: A digital pulse shaping module provides a digital waveform such as a pulse shape, gating or a synchronizing digital signal for use with a pulsed laser oscillator. The digital pulse shaping module includes a waveform data generator that generates N-bit words having a number N of bits. A serialiser is further provided to receive the N-bit words from the waveform data generator and outputs each bit individually in a series of bits corresponding to the digital waveform. The digital pulse shaping module further includes a delay module that provides a fine delay in the outputting of the bits by the serialiser. This fine delay corresponds to a number of bits smaller than N, impacting on the timing of the outputted signal at the bit level. A pulse shaping generator has a plurality of digital pulse shaping modules.

Abstract: A digital pulse shaping module for controlling a pulsed laser oscillator according to a digital input waveform is provided. The pulse shaping module includes a clock generator generating a plurality of phase-related clock signals and a shape generator which outputs a digital shape signal corresponding to the digital input waveform in Double Data Rate in response to the clock signals. A DAC converts the digital shape into an analog shape signal. The analog shape signal may be used to control the current source of a laser seed source or modulators in the laser oscillator shaping a seed light signal. Optionally, the pulse shaping module may also output a gate control signal having a predetermined timing relationship with respect to the digital shape signal.

Abstract: 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.

Abstract: An optical fiber amplifier system is described and comprises a first optical fiber having a doped core with a first gain spectral profile upon being pumped. The first optical fiber is adapted to receive an optical signal from a light source. A second optical fiber has a doped core with a second gain spectral profile upon being pumped. The second optical fiber is optically coupled to the first optical fiber. A continuous wave pump light system is optically coupled to the fibers so as to store energy in the fibers for a subsequent amplification of the optical signal from the light source. An overlapping configuration is provided between the first gain spectral profile and the second gain spectral profile so as to reduce energy depletion in one of the optical fibers from amplification of spontaneous emission generated by another of the optical fibers.

Abstract: A tunable pulsed laser source comprising a seed source adapted to generate a seed signal and an optical circulator. The optical circulator includes a first port coupled to the seed source, a second port, and a third port. The laser source also includes an amplitude modulator characterized by a first side and a second side. The first side is coupled to the second port of the optical circulator. The laser source further includes a first optical amplifier characterized by an input end and a reflective end including a spectral-domain reflectance filter. The input end is coupled to the second side of the amplitude modulator. Moreover, the laser source includes a second optical amplifier coupled to the third port of the optical circulator.

Abstract: A pulsed fiber laser oscillator and laser systems incorporating such laser oscillators are presented. The laser oscillator first includes a light generating module which generates optical pulses having an initial spectral profile. A spectrum tailoring module tailors the initial spectral profile of the optical pulses by imposing a phase variation on each optical pulse according to an optimized phase varying function. The optimized phase varying function has one of a rectified sinusoidal shape, a parabolic shape and a rectified parabolic shape. Laser systems incorporating such oscillators may be of a MOPA configuration, and may further include a nonlinear crystal for frequency conversion or a bulk solid-state amplifier.