A laser apparatus includes a chamber accommodating a pair of discharge electrodes, a gas supply and exhaust device configured to supply laser gas to an interior of the chamber and exhaust laser gas from the interior of the chamber, and a controller. The controller performs first control to control the gas supply and exhaust device so as to suspend laser oscillation and replace laser gas in the chamber at every first number of pulses or first elapsed time, and second control to control the gas supply and exhaust device so as to suspend laser oscillation and replace laser gas in the chamber before the first control at every second number of pulses less than the first number of pulses or second elapsed time less than the first elapsed time.

A system includes a laser source operable to provide a laser beam, a laser amplifier having a gain medium operable to provide energy to the laser beam when the laser beam passes through the laser amplifier, and a residual gain monitor operable to provide a probe beam and operable to derive a residual gain of the laser amplifier from the probe beam when the probe beam passes through the laser amplifier while being offset from the laser beam in time or in path.

A high-power laser beam with an arbitrary intensity profile is produced. Such beam has a variety of uses including for laser materials processing such as powder bed fusion additive manufacturing. Several challenges in additive manufacturing are mitigated with the present non-uniform intensity laser profiles. Nonuniform shapes include a set of intensity pixels in a line that could print a wide stripe area instead of just a single line. One example uses the multimode interference pattern from the output of a ribbon fiber which is imaged onto a work piece. The interference pattern is controlled to allow turning on or off of pixels along a line which can be used to shape the beam and form the additively manufactured part.

Systems and methods are described for producing an amplitude-modulated laser pulse train. The laser pulse train can be used to cause fluorescence in materials at which the pulse trains are directed. The parameters of the laser pulse train are selected to increase fluorescence relative to a constant-amplitude laser pulse train. The amplitude-modulated laser pulse trains produced using the teachings of this invention can be used to enable detection of specific molecules in applications such as gene or protein sequencing.

A method includes driving, while producing a burst of pulses at a pulse repetition rate, a spectral feature adjuster among a set of discrete states at a frequency correlated with the pulse repetition rate; and in between the production of the bursts of pulses (while no pulses are being produced), driving the spectral feature adjuster according to a driving signal defined by a set of parameters. Each discrete state corresponds to a discrete value of a spectral feature. The method includes ensuring that the spectral feature adjuster is in one of the discrete states that corresponds to a discrete value of the spectral feature of the amplified light beam when a pulse in the next burst is produced by adjusting one or more of: an instruction to the lithography exposure apparatus, the driving signal to the spectral feature adjuster, and/or the instruction to the optical source.

A laser system may include a controller configured to direct a plurality of temporally spaced-apart electrical pulses to a device that optically pumps a lasing medium, and a lasing medium configured to output a quasi-continuous laser pulse in response to the optical pumping. The plurality of temporally spaced-apart electrical pulses may include (a) a first electrical pulse configured to excite the lasing medium to an energy level below a lasing threshold of the lasing medium, and (b) multiple second electrical pulses following the first electrical pulse. The quasi-continuous laser pulse is output in response to the multiple second electrical pulses.

The laser apparatus includes a master oscillator, an amplifier, a power source, and a controller to control the power source. The controller controls the power source such that an excitation intensity of the amplifier in a burst oscillation period performing the burst oscillation is a first excitation intensity, controls the power source such that, if the predetermined repetition frequency is a first repetition frequency, an excitation intensity of the amplifier in a suspension period suspending the burst oscillation is a second excitation intensity equal to or lower than the first excitation intensity, and controls the power source such that, if the predetermined repetition frequency is a second repetition frequency higher than the first repetition frequency, the excitation intensity of the amplifier in the suspension period is a third excitation intensity lower than the second excitation intensity.

A multi-path optical amplification system includes a modulated light source emitting 1 modulated light, a first signal splitter coupled to receive the modulated 1 light providing a first 1 modulated light signal and second 1 modulated light signal. A first optical amplifier is for receiving the first 1 modulated light signal and generating a first amplified output signal, and a second optical amplifier is for receiving the second 1 modulated light signal and generating a second amplified output signal. A first collimator assembly is coupled to receive the first amplified output signal and provide a first output beam having a first beam divergence (D1) and a second collimator assembly is coupled to receive the second amplified output signal and provide a second output beam having a second beam divergence (D2).

The invention provides an excimer laser system including a means for calibrating laser output to compensate for increased variation in laser optical fibers.

A system 200 for altering laser pulse duration includes a chirped fiber Bragg grating (cFBG) 122, a Faraday rotator 230, a retroreflector 240, and a fiber-optic polarization combiner 210 coupled to the chirped fiber Bragg grating 122 via the Faraday rotator 230. The combiner 210 directs a laser pulse via the Faraday rotator 230 to a first reflection in the cFBG 122, then directs the laser pulse to the retroreflector 240, then directs the laser pulse via the Faraday rotator 230 to a second reflection in the cFBG 122, and then emits the laser pulse. A three-port fiber-optic circulator 250 may serve as an input/output interface. Another system for altering laser pulse duration includes a cFBG 122, a fiber-optic polarization combiner 210 coupled to the cFBG 122, and a four-port fiber-optic circulator 550 coupled to the combiner 210 to direct a laser pulse from through the combiner 210 to the cFBG 210 via two different paths. These systems passively achieve two passes through the same cFBG 210.