A digital counting and display system and methods for use with a laser rangefinder that counts backscattered laser beams and displays a distance between a laser and a target. The laser rangefinder includes a laser configured to emit a pulsed laser beam, an afocal Gallilean telescope configured to receive backscattered laser pulses and generate a series of focused backscattered laser pulses, a silicon avalanche photodetector connected to the afocal Gallilean telescope, configured to generate a series of currents signal proportional to the series of focused backscattered laser pulses, a low noise, multistage amplifier connected to the silicon avalanche photodetector, configured to generate a series of linearly changing amplified voltage signals from the series of current signals, an analog-to-digital converter configured to convert the series of linearly changing amplified voltage signals to a series of digital voltage signals, and a digital counting and display circuit connected to the analog-digital converter.

A multi-wavelength mid-infrared laser pulse train cavity dumped laser based on Nd:MgO:APLN crystal is disclosed. In response to the needs in the field of differential absorption lidar, it is necessary to introduce multi-fundamental frequency light pulse accumulation and superposition, and parametric light synchronization pulse compression technology in the multi-wavelength mid-infrared laser operating mechanism. To this end, a splayed parametric light oscillation cavity formed in conjunction with a Nd:MgO:APLN crystal is disclosed, wherein it is possible to obtain multi-wavelength mid-infrared laser pulse train output with narrow pulse width and high peak power, meeting the needs of differential absorption lidar for mid-infrared lasers.

A multi-wavelength mid-infrared laser pulse train cavity dumped laser based on Nd:MgO:APLN crystal is disclosed. In response to the needs in the field of differential absorption lidar, it is necessary to introduce multi-fundamental frequency light pulse accumulation and superposition, and parametric light synchronization pulse compression technology in the multi-wavelength mid-infrared laser operating mechanism. To this end, a splayed parametric light oscillation cavity formed in conjunction with a Nd:MgO:APLN crystal is disclosed, wherein it is possible to obtain multi-wavelength mid-infrared laser pulse train output with narrow pulse width and high peak power, meeting the needs of differential absorption lidar for mid-infrared lasers.

An active element-doped optical fiber includes: a core that includes first and second regions. The first region ranges from a central axis to a predetermined radius, and is doped with an active element excited by excitation light. The second region surrounds the first region with no gap, extends to an outer peripheral surface of the core, and is not doped with the active element. The core satisfies 0.1 d<ra<d, where ra is a radius of the first region and d is a radius of the core. The core has, in a region of 0.2 d<r0.9 d, a maximum value position at which a refractive index becomes maximum, where r is a distance from a central axis of the core in a radial direction.

A mid- to far-infrared solid state Raman laser system comprising a resonator cavity comprising: an input reflector adapted to be highly transmissive for light with a first wavelength in the range of about 3 to about 7.5 micrometers for admitting the first beam to the resonator cavity; and an output reflector adapted to be partially transmissive for light with a second wavelength greater than about 5.5 micrometers for resonating the second wavelength in the resonator and for outputting an output beam, the input reflector further being adapted to be highly reflective at the second wavelength for resonating the second wavelength in the resonator; and a solid state diamond Raman material located in the resonator cavity for Raman shifting the pump beam and generating the second wavelength.

Ultrashort pulse fiber amplifier having a pulse width from 200 ps to 200 fs comprising a rare earth oxide doped multicomponent glass fibers for laser amplification, including a core and a cladding, the core comprising at least 2 weight percent glass network modifier selected from BaO, CaO, MgO, ZnO, PbO, K.sub.2O, Na.sub.2O, Li.sub.2O, Y.sub.2O.sub.3, or combinations; wherein the mode of the core is guided with step index difference between the core and the cladding, a numerical aperture of the fiber is between 0.01 and 0.04; core diameter is from about 60 microns to about 150 microns, and a length of the gain fiber is shorter than 60 cm.

Ultrashort pulse fiber amplifier having a pulse width from 200 ps to 200 fs comprising a rare earth oxide doped multicomponent glass fibers for laser amplification, including a core and a cladding, the core comprising at least 2 weight percent glass network modifier selected from BaO, CaO, MgO, ZnO, PbO, K.sub.2O, Na.sub.2O, Li.sub.2O, Y.sub.2O.sub.3, or combinations; wherein the mode of the core is guided with step index difference between the core and the cladding, a numerical aperture of the fiber is between 0.01 and 0.04; core diameter is from 25 to 120 micron, and a length of the gain fiber is shorter than 60 cm.

Ultrashort pulse fiber amplifier having a pulse width from 200 ps to 200 fs comprising a rare earth oxide doped multicomponent glass fibers for laser amplification, including a core and a cladding, the core comprising at least 2 weight percent glass network modifier selected from BaO, CaO, MgO, ZnO, PbO, K.sub.2O, Na.sub.2O, Li.sub.2O, Y.sub.2O.sub.3, or combinations; wherein the mode of the core is guided with step index difference between the core and the cladding, a numerical aperture of the fiber is between 0.01 and 0.04; core diameter is from 25 to 120 micron, and a length of the gain fiber is shorter than 60 cm.

Ultrashort pulse fiber amplifier having a pulse width from 200 ps to 200 fs comprising a rare earth oxide doped multicomponent glass fibers for laser amplification, including a core and a cladding, the core comprising at least 2 weight percent glass network modifier selected from BaO, CaO, MgO, ZnO, PbO, K.sub.2O, Na.sub.2O, Li.sub.2O, Y.sub.2O.sub.3, or combinations; wherein the mode of the core is guided with step index difference between the core and the cladding, a numerical aperture of the fiber is between 0.01 and 0.04; core diameter is from 25 to 120 micron, and a length of the gain fiber is shorter than 60 cm.

Ultrashort pulse fiber amplifier having a pulse width from 200 ps to 200 fs comprising a rare earth oxide doped multicomponent glass fibers for laser amplification, including a core and a cladding, the core comprising at least 2 weight percent glass network modifier selected from BaO, CaO, MgO, ZnO, PbO, K.sub.2O, Na.sub.2O, Li.sub.2O, Y.sub.2O.sub.3, or combinations; wherein the mode of the core is guided with step index difference between the core and the cladding, a numerical aperture of the fiber is between 0.01 and 0.04; core diameter is from 25 to 12.0 micron, and a length of the gain fiber is shorter than 60 cm.