Maximum amplification and single amplified ultra-short laser pulse selected from a three stages four passes amplifiers
chain will be presented. The configuration of the amplifiers chain need to be set up and aligned to avoid the inter-stages
reflection. The amplified spontaneous emission pulse shape as well as the synchronization between the pumping pulse
and the seed pulses train can be optimized to have maximum amplification and a single amplified pulse only. The
amplification results and the detail analysis will be presented.
We have developed a terawatts high intensity, sub-hundred femtosecond ultra-short pulses, 248.6 nm ultraviolet
laser systems, with dye seed laser in blue-green regime, amplified in the multi-stage dye amplifiers and then
frequency doubled and finally amplified with multiple-passes KrF amplifier. We have characterized the system
performances, the amplified interaction volume, the amplified spontaneous emission optimization, the Excimer
amplifier and the system merits.
The modeling and characterization of simple semiconductor wafers of GaAs, InP, etc. as passive laser modulators that
give burst of Q-switched pulse and Q-switched mode-locking pulses train will be present in detail. Various simple and
inexpensive semiconductor wafer pieces were used to passively modulate the Nd:hosted solid state laser systems, and the
mechanism of saturable absorption that give burst of Q-switched pulse and Q-switched mode-locking pulses were
studied theoretically and experimentally. We have established complete passive laser saturable absorber model, and the
numerical derivation results are quite coincident to the experimental results.
Single amplified ultra-short laser pulse is very important in basic scientific researches as well as in
ultra-high power laser applications. The high intensity ultra-short laser pulse usually comes from the
mode-locked pulses train. It is important to develop a laser amplifier configuration that can optimally
amplify single ultra-short laser pulse. We present in this research, first by controlling the
synchronization of the amplifiers chain, and then optimally adjust the shape of amplified spontaneous
emission of each amplifier, we can select the single amplified ultra-short laser pulse out of the seed
ultra-short pulses train and boost the laser pulse to the maximum power amplification. An adjustable
repetitive single pulse high intensity ultra-short pulse UV laser system was developed and the laser
outputs were extracted at various ends and characterized in detail.
High intensity ultra-short pulse UV laser system found many applications in atomic researches,
picosecond phenomena and bio researches. We present a high intensity ultra-short pulse UV laser
system that not only can generate single amplified high intensity ultra-short pulse UV laser system, but
also can be operated in repetitive mode up to tenths pulses per second. Our complete laser system
could also be extract as femtosecond ultra-short pulses sub-system, three amplifiers four passes single
amplified medium to high intensity ultra-short pulse laser sub-system, and ultimately, high intensity
ultra-short pulse UV laser system. Techniques of single amplified high intensity ultra-short pulse of this
laser system are presented and characterized.
Noise and fluctuations are of fundamental importance in all aspects of laser systems, especially in laser
amplifiers. We present the results that not only enhance the signal seed sources to the maximum
amplification, but also produced single amplified signal source. The outputs of the complete high
intensity ultra-short pulse UV laser system are presented and characterized.
Five types of passive Q-switched as well as simultaneously Q-switch mode-locked modulators: plastic
dye sheets ( Kodak 9850 cellulose acetate dye sheets), lithium fluoride crystals containing F2- color
centers ( LiF: F2-), chromium doped yttrium aluminum garnet crystals ( Cr4+:YAG), ionic color filter
glass ( Schott RG1000 color filter glass) and the single crystal semiconductor wafers ( GaAs, Fe doped
InP, Zn doped InP, S doped InP, etc.) used for the modulation of the Nd:hosted(Nd:YAG, Nd:YVO4,
and Nd:LSB) lasers have been investigated in detail in our researches. We have also investigated into
the applications of the Q-switch mode-locked pulses train for the development of higher resolution
solid state laser range finder. We will also present the high accuracy laser ranging results, the
micro-motor that driven mechanical parts from the stepping digital ranging readout, to precisely control
the best focus of a miniature zoom lens modular. The core simultaneously Q-switch mode-locked
modulators microchip laser is the key part of our automatic optical inspection system.
A continuous-wave phase-shift laser range finder employs a novel multimodulation frequency method associating an undersampling analog-digital converter (ADC) with digital synchronous detection. This presentation greatly improves measured phase accuracy and reduces prior art scheme complexities. The novel patented design includes one phase-lock-loop (PLL) chip to produce a multimodulation frequency, one analog-to-digital converter operating at a low sampling rate, and an effective algorithm to calculate the final distance, which has encoded computing codes, and is implemented into compact computing circuits but without mixers and redundant components. The experimental results prove that a nonambiguity range is easily achieved to 1.5 Km when the modulation frequency is operated at 0.1 MHz. The measured accuracy approaches 2.9 mm using the same apparatus when the modulation frequency is tuned to 14.5 MHz. Dynamic range can reach 5.2×105 without a very high modulation frequency below 15 MHz, as revealed by a detailed analysis.
Novel laser range finding algorithms and a single element laser range finder transceiver modular component have been developed and put in practical use. The laser range finder measure up to 60 m maximum and with resolution of 1 to 3 mm. Multi-modulation frequencies high resolution ranging algorithms first use only a lower or medium frequency to obtain the non-ambiguity range (NAR), and then by using higher relative frequency with locked phase, we can obtain high resolution ranging results.
Passive Q-switch modulators of plastic dye sheets ( Kodak 9850 cellulose acetate dye sheets), lithium fluoride crystals containing F2- color center ( LiF: F2-), chromium doped yttrium aluminum garnet crystals (Cr4+:YAG), ionic color filter glass (Schott RG1000 color filter glass) and the single crystal semiconductor wafers (GaAs, Fe doped InP, Zn doped InP, S doped InP, etc.) have been investigated in our research. Especially in use those of the single crystal semiconductor wafer saturable absorbers, give us idea of developing the semiconductor substrate microchip lasers.
We have investigated many different types of Nd solid state lasers and the passive modulator materials that can passively Q-switch, mode-lock, Q-switched mode-lock all the above solid state lasers. The mechanism of the typical Q-switched mode-lock mechanisms were proposed and analyzed in detail. In all the microchip laser developments, the only tolerance that can reduce the physics size, optimize the modulated output efficiency and minimize the component price is to use the doped single crystal semiconductor saturable absorbing modulators as we are proposing. We have used the MEMS technologies for the fabrication of the most compact, highest efficiency and most low price semiconductor substrate microchip laser. Two out of four components of the various direct generation as well as OPO generation of the microchip lasers that generate visible, near infrared and infrared wavelengths and with Q-switch, mode-lock, Q-switched mode-lock modulation could be achieved.
Q-switched mode-lock pulses train had been obtained stably in our microchip lasers as well as in our new modular semiconductor substrate microchip lasers. We are working on the applications of those Q-switched mode-lock pulses train to increase the measured resolution in the traditional time of flight as well as the phase enhanced high resolution time of flight laser range finder systems.
We have investigated many different type of solid-state lasers and the materials that can passively Q-switch, mode-lock, Q-switched mode-lock all the above solid-state lasers. In the advanced applications of the solid-state lasers, the microchip laser configurations had been used satisfactory for nearly the past decade. In all the microchip laser developments, the only tolerance that can reduce the physics size, optimize the modulated output efficiency and minimize the component price is to use the doped single crystal semiconductor saturable absorbing modulators as we have published. Here we use the MEMS technologies for the fabrication of the most compact, highest efficiency and most low price semiconductor substrate microchip laser. Two out of four components of the various OPO microchip lasers, that generate visible, near infrared and infrared wavelengths and with Q-switch, mode-lock, Q-switched mode-lock modulation could be achieved.
Various single crystal semiconductor wafers that can passively modulate the microchip solid-state lasers were investigated. Direct laser output at eye-safe wavelengths as well as wavelength shifting from 1.06 μm to the eye-safe wavelengths can satisfactory use those single crystal passive semiconductor saturable absorbers.
Five kinds of the laser passive modulators: single crystal semiconductor wafers, plastic dye sheets, lithium fluoride crystals containing F2- color center, chromium yttrium aluminum garnet crystals and ionic color filter glass that can Q-switched modulate, mode-locked modulate, and Q-switched mode-locking modulate the conventional flash-lamp pumped Nd:hosted lasers, Er:Glass eye-safe solid-state lasers as well as all those of diode-pumped Nd:hosted and Er:Glass eye-safe microchip lasers are presented. Theoretical model are proposed and the detail analysis are presented.
Fiber optic strain sensor systems using fiber Bragg grating have been developed in our Section with time demultiplexing phase stabilized feed back Fabry-Perot tunable filter and signal processing technologies. The system can resolve < 1 μ strain, with measuring range of 4000 μ strain; and can monitor 20 points simultaneously. It has been used in real time long term hazard investigation and warning system on the bridges and traffic high-pass ways. The data from these smart fiber optic distributed stress and strain sensing systems had constantly been observed with satisfactory results. Our fiber optic communication system is a bi-directional audio-video and data signal transmission system. The source laser diodes are TE cooled with temperature control circuits. The system is dual audio bi-directional transmission and receiving channel with bandwidth 4.8 KHz. Video one direction transmission and receiving, meets NTSC specification with bandwidth 6 MHz. Dual data signals bi-directional transmission adn receiving channel, meets RS-232C specification and the Buad rate are 9.6 Kbps. The sstems are carefully designed and fabricated to meet the environmental wide temperature range conditions as well as high vibration and shock mobile transportation.
Slowly opened Q-switch modulation superior in giant pulse operation. All of active and passive modulators: LiNbO3-Plastic Dye Sheets-LiF:F2-Cr4+:YAG-RG1000 Color Filters-InP and GaAs semiconductor slabs have been investigated and analyzed. Diode-pumped microchip all solid state lasers using the above passive modulators are demonstrated respectively..
Four kinds of currently available Nd:hosted laser passive Q-switch and mode-lock modulators: plastic dye sheet, LiF:F2- color center crystal, Cr4+:YAG crystal and RG1000 colored glass filter were investigated in detail for the diode-pumped Nd:hosted solid state lasers. Nd:YVO4 lasers, ?-Nd:YAG lasers as well as conventional Nd:YAG lasers, Nd:Glass lasers had been set up for investigations. Detailed analyses of the mode-locking effect in combination with Q-switching were provided. Interpretation given based on the characteristic features of the materials, like saturation intensity and relaxation times. The results explained at hand of adequate equations derived with respect to the relevant physical parameters of the materials.
Phase conjugate phenomenon and mechanism with BaTiO3 photorefractive crystals have been investigated using various cw sources and all the way down with ultrashort pulses of the femtosecond region. Our laser sources support all the various pulsewidths at a wide range of different spectral regions.
Lithium fluoride crystal containing F2- color centers (LiF:F2-) is a room temperature stable, with annealing temperature higher than 400 degree(s)C; long lifetime, over ten years; near IR, 0.8 micrometers to 1.2 micrometers saturable absorbing color centers crystal. It could be used to passively Q-switch or mode-lock solid state Nd doped laser systems. What is more, due to the better heat dissipating capability of this crystal compared to the saturable absorber dye sheet with cellulose acetate host, it could be used to passively Q-switch Nd laser systems up to 30 pps repetition rate without any forced cooling.
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