The 1.5 μm pulsed 3-stage all-fiber MOPA source seeded by a directly modulated DFB laser was developed. It operated
at the repetition rate ranging from 400 kHz to 2 MHz and delivered up to 6.5 μJ in 1-ns pulse. The total signal gain of up
to 57 dB and the maximum average output power of over 2.8 W (at 2 MHz) were demonstrated when the total pump
power of the MOPA was 10.64 W. The amplified pulses were very stable and did not reveal either duration and shape
change in relation to input pulses generated by the seed.
The characteristics of a Q-switched neodymium-doped double-clad fiber laser were presented. Based on the proposed differential equations with suitable boundary and initial conditions, a numerical model was developed to simulate this fiber laser. All the calculations were based on wave-travelling approach. Using this model, pulse duration and the energy of generated pulses can be predicted. In the experiment, pulses with the energy of 0.36mJ (84ns) and 154μJ (48ns) at the repetition rate of 500Hz were achieved for 5 and 3-m long fiber, respectively. The extractable energy was limited due to low energy storage and the fiber-end facet damage. The results obtained numerically agree well with the experimental results.
In this paper we report on a record 1.4 MW peak power, actively Q-switched Er:YAG laser operating at 2.94 μm. As a result of our experiment, at 3 Hz repetition rate, we achieved 91 ns pulses with 137 mJ energy. At higher repetition rate (10 Hz) the laser generated 100 ns pulses with 35 mJ energy. These results, according to our knowledge, are the best that have been ever achieved.
This paper presents a Q-switched Er:YAG laser generating in near infrared range. In this laser system Pockels cell (as an active switch) was applied. For the optimal repetition rate of 10 Hz and maximal pumping energy of 62 J over 15 mJ of the ouptut laser energy was achieved. The pulses generated were characterized by time duration of 115 ns corresponding with 130 kW peak power. Non-linear absorbers allowing to build an effective losses modulator are also discussed.
Problems related to optical activation of high-power fiber lasers are presented in this work. Double-clad fiber lasers with different cross sections of inner clad are discussed. The authors of this study have presented an alternative attempt at analyzing the problems touched upon. In this paper a computer program allowing visualization of the path of the light rays in geometrical optics approximation is presented. This program visualizes a trajectory of the light rays along the fiber and the result is the graphic presentation of distribution of radiation transmitted along the fiber (on cutting plane of the fiber). Circle, stadium and D-shaped clads were considered. The results of the analyses carried out clearly indicate unquestionable superiority of D-shaped and stadium-shaped fibers over fibers with circular cross section, when the efficiency of activation is taken into account.
In this paper a high-power Nd-doped double-clad fiber laser is presented. We obtained 10 W cw-output power from 20 m long fiber with laser core in 12 μm diameter (NA = 0.12) and pump core in 400 μm diameter (D-shaped, NA = 0.38). Nd-doping concentration has been at 1300 ppm level and attenuation in the laser core has been less than 10 dB/km (for λ = 1100 nm). High power diode laser module operating at λ = 808 nm has been used as a pump unit. This pump ensured 30 W cw output power. As a result, we have built a coherent source of radiation generating 10 W cw output power with 63 percent slope efficiency.
In this paper high power Yb-doped double-clad fiber laser is presented. A Yb3+-silica fiber laser has been cladding pumped at 937 nm by a InGaAs semiconductor laser diode and operated with the slope efficiency of 73 ± 3% with respect to the incident pump power. We obtained 4 W cw-output power when working with 20-m long fiber with laser core in 7 μm diameter (cut-off wavelength - 1 μm) and pump core in 120 x 120 μm (rectangle-shaped, NA = 0.6). Yb-doping concentration has been at the level 3 - 10 • 1019 cm-3 and attenuation in laser core has been 8 - 12 dB/km. The fiber laser operated at 1084 nm.
In this article we present a diode pumped fiber laser. An active Q-switched fiber laser system has been elaborated. An active neodymium-doped double-clad optical fiber was used as an active medium. For low repetition rate (20 Hz) we achieved pulses with 211 ns time duration and 12 μJ energy. Applying high repetition (10 kHz) driver of Pockels cell we achieved pulses with 250 ns time duration and 300 μJ energy (for 500 Hz repetition rate). The length of the active fiber was 5 m. The pump source delivered 30 W continuous output power at 808 nm wavelength.
The peak power of 0.65 MW and energy of 1.9 mJ at 1572 nm-wavelength was demonstrated in a singly resonant diode pumped intracavity optical parametric oscillator (IOPO). The energy of 4.3 mJ in fundamental mode at 1064 nm-wavelength with 15 ns-pulse duration in passively Q-switched regime was achieved in the arranged for IOPO Nd:YAG slab laser pumped by 300 W quasi-cw diode array. The KTP crystal, size of 20×5×5 mm3, 'x-cut’ for non-critically phase-matched parametric generation at the signal wavelength of 1572 nm was used in experiments. In optimized, with respect to single pulse energy, IOPO cavity with output coupler of 50% transmission at signal wavelength the five-fold shortening of signal pulse duration with respect to 1064 nm pump radiation was observed. The twice-higher level of signal peak power of 650 kW, compared to pump laser at 1064 nm in the same cavity without OPO, was achieved. The conversion efficiency of 44% with respect to 1064 nm pump beam and 3.8% with respect to diode pump energy was demonstrated.
The state of development of constructions and technology of elements used in high-power fiber laser systems is presented. Laser working conditions related to constructions and new technology limit maximum cw-output power and level of energy (pulse regime). The analysis concerns recent available active dopants used in active optical fiber lasers and methods of its activation. The perspectives of progress of high-power fiber lasers have also been presented.
The possibility of using short-pulse laser with interferometric fiber-optic for diagnostic of tissues is presented. The Cr:Forsterite laser operated at 1300 nm is proposed and the first characteristics of such laser are presented. The detection of backscattering light is obtained by using the Michelson type fiber-optic interferometer. The main aspect of signal processing based on a phase calculation as well as theoretical system description in the Jones’ matrix approach is also presented.
In this paper a high-power Nd-doped double-clad fiber laser is presented. From 20 m long fiber with laser core in 12 μm diameter (NA=0.12) and pump core in 400 μm diameter (D-shaped, NA=0.38) we obtained 10 W cw-output power. Nd-doping concentration has been at the level 1300 ppm and attenuation in the laser core has been less than 10 dB/km (for λ=1100 nm). High power diode laser module operating at λ= 808 nm has been used as a pump unit. This pump ensured 30 W cw output power. As a result we have built a coherent source of radiation generating 10 W cw output power with slope efficiency 63 per cent.
A tunable Cr:Forsterite laser with intracavity Nd:YAG pump and its experimental results are presented. To our best knowledge, this is the first tunable intracavity pumped Cr4+ ion activated laser. A theoretical model of saturable absorber operating both as a laser and an intracavity Q-switch for its pumping laser is presented and discussed. A good agreement of the numerical calculations with the experimental results has been obtained.
The paper presents laser sets, including forsterite laser, applicable for the HpD therapy. We describe the laser sets pumped by the Q-switched Nd:YAG laser pulse, generating radiation within a therapeutic range and diagnostic one as well as the set generating within the q-W regime. We discuss the results of investigations carried out with the laser set for diagnosis. The set comprises the KZnF3 laser with a ruby pump. The forsterite laser pumped by the q-CW Nd:YAG laser, at 20 W of a pump power, can generate radiation of average power of about 400 mW at wavelength of (lambda) equals 1270 nm or radiation of average power of 150 mW at wavelength of 630 nm. The tunable range of the set is (lambda) equals +/- 20 nm FH and (Delta) (lambda) equals +/- 10 nm for the SH of forsterite laser. We have also analyzed other laser sets fulfilling requirements of the HpD diagnosis and therapy.
The lamp pumped Cr:Tm:Ho:YAG laser, with slope efficiency about 2%, and up to 17 W average power was demonstrated. The output energy, average power, as well as M2 parameter were investigated in dependence on temperature and cavity configuration for wide range of pump power levels. The optimized cavity with concave facets rod and flat mirrors enabled to shift stability range to 2 kW of pump power.
The possible laser systems for HpD tumors diagnostics and therapy are presented in this paper. The principal laser system for those applications is based on Forsterite laser. Generation two wavelengths -- for therapy ((lambda) equals 630 plus or minus 10 nm) and diagnostics ((lambda) equals 400 plus or minus 5 nm) are possible in those systems.
Single frequency generation output with energy level about 1 mJ in electro-optically Q- switched Nd:YVO4 laser pumped by 1 cm quasi-cw laser diode bar is demonstrated. Above 170 kW peak power in 5.6 ns pulse duration was achieved. The low threshold, near diffraction limited output, short cavity length advantage is the Nd:YVO4 laser for low energy, high pulse power in coherent velocimetry, range finding and Doppler radar applications.
The paper describes an application of the GPIB system for measurement automation of the laser beam and laser devices parameters. The setup of the measurement system and examples of the obtained results, as well as methods of verification of measurements accuracy, are described. Acquisition rates obtained in our system are also given.
The paper describes some of the results of a research series of the elements of the laser oscillator which are included in the set of a laser designator-rangefinder. The choice of optimized construction of a pump cavity and proper configuration of elements in a laser resonator was the subject of the investigations.
Some ion doped crystals of the transient group of metals have a broad band of luminescence in the VIS/IR spectral region, and thus they are suitable for the design of tunable lasers free from a series of disadvantages of tunable dye lasers. Physical properties and advantages of solid state lasers using the Ti-doped sapphire and Cr-doped forsterite crystals are reviewed.
The results of laser action in Cr, Tm, Ho doped YSAG and YAG are presented in this paper. Output characteristics of these holmium lasers acting in different conditions (a few laser cavities, resonator optics, pumping pulse energy, and pulse duration) are shown. One interesting result has been obtained -- optimal pump pulse duration strongly depends on the kind of laser medium host (for YAG it is equal to 500 - 600 microsecond(s) ).
The paper presents a description of a construction of the ophthalmological set LH-58 with the holmium laser. Results of preliminary medical tests of eye lens curvature correction carried out by means of this set are given.
Results of tuned Ti:sapphire laser investigations are presented in this paper. Shortening and stabi 1 i zat ion of pulse durat ion have been achieved us ing the SBS cell inside of the laser cavity. The main advantages of this laser and its features are shown. i: