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A nanosecond-pulse power source transfers energy to electrons of atmospheric pressure discharges in a nanosecond-scale rising time and shows different plasma chemistry than a slowly varying sinusoidal discharge. We report how the operation parameters, such as applied voltage, pulse duration, and repetition frequency, affect the discharge characteristics and the surface property of polydimethylsiloxane (PDMS). The applied voltage controls the energy delivery per a pulse cycle, and the repetition frequency dominantly affects the plasma density in a long-term operation. The water contact angle, the optical emission spectroscopy, and the atomic force microscope diagnostics on the PDMS are presented. While the polarity of the nano pulse bias changes the emission length of the plasma jet, the hydrophilicity is not affected by it because the chemical reactions by radicals are more dominant than the physical reactions of charged particles on PDMS.

We present images of microholes drilled in diamond using a homemade femtosecond Yb : KGW laser. We use a femtosecond laser source emitting pulses with a duration of 230 fs at a wavelength of 1030 nm, the focusing spot size amounting to 8.9 μm. The effect of the pulse energy and the number of pulses on the microhole geometry (hole diameter, circularity, taper angle, and drilling quality) is evaluated. The obtained results demonstrate the feasibility of drilling of hourglass-shaped holes in a diamond sample, which have similar diameters at the hole entrance (92 μm) and exit (95 μm), but a much smaller diameter (28 μm) at a certain waist section inside the hole.

A three-stage laser amplification system based on thin Yb : YAG rods with diode laser pumping is developed and fabricated. In this system, the average power of a continuous train of femtosecond pulses from a Yb : KGW master oscillator with a pulse repetition rate of 80 MHz and initial pulse duration of 128 fs was raised by a factor of 100 to above 100 W. Preliminarily chirped laser pulses provided compensation of dispersion in optical elements of the system and obtaining 580-fs output pulses. The longer duration of output pulses relates to spectrum narrowing in the amplifiers.

Label-free in vivo imaging is crucial for elucidating the underlying mechanisms of many important biological systems in their most native states. However, the applicability of existing modalities has been limited to either superficial layers or early developmental stages due to tissue turbidity. Here, we report a synchronous angular scanning microscope for the rapid interferometric recording of the time-gated reflection matrix, which is a unique matrix characterizing full light-specimen interaction. By applying single scattering accumulation algorithm to the recorded matrix, we removed both high-order sample-induced aberrations and multiple scattering noise with the effective aberration correction speed of 10,000 modes/s. We demonstrated in vivo imaging of whole neural network throughout the hindbrain of the larval zebrafish at a matured stage where physical dissection used to be required for conventional imaging. Our method will expand the scope of applications for optical imaging, where fully non-invasive interrogation of living specimens is critical., A major challenge of in vivo imaging is imaging deeper, including in turbid tissue. The authors report an adaptive optics based microscope that uses coherent single scattering signal to reduce sample-induced aberrations and enable fast deep-tissue imaging of in vivo larval zebrafish brain.

This paper proposes a solid-state pulsed power modulator (PPM) with fast rising/falling time and high repetition rates to drive pockels cells. Since the proposed circuit is based on the modular structure using silicon carbide (SiC) metal–oxide silicon field-effect transistors ( MOSFET s) for bypass devices as well as for main switches, it can achieve fast switching speed and high reliability. In addition, by a control scheme employing the voltage difference, the proposed circuit can accomplish a high repetition rate and short pulsewidth. Design and implementation of 1.8-kV PPMs with repetition rate of 1 MHz and rising/falling time below 6 ns are presented. Also, important issues for the practical use of the SiC-based PPM are discussed. Experimental results from the developed PPMs are shown to verify the proposed works.

In this research, an all- polarization-maintained semiconductor saturable absorber mirror (SESAM) mode-locked fiber oscillator and its amplification by Yb-doped fiber and a Yb:YAG thin rod are presented. From a ring-type cavity configuration created with commercially accessible components, including SESAM, the dissipative soliton fiber oscillator exhibits stable mode-locking near 1030 nm. Subsequent three-stage fiber amplifiers pumped by single-mode fiber-coupled laser diodes and a single-stage Yb:YAG thin-rod amplifier boost the output power to 11.3 W at a repetition rate of 495 kHz. After pulse compression, a pulse duration of 758 fs is achieved with output power and pulse energy levels of 9 W and 18.2 μJ, respectively.

Optical imaging of objects embedded within scattering media such as biological tissues suffers from the loss of resolving power. In our previous work, we proposed an approach called collective accumulation of single scattering (CASS) microscopy that attenuates this detrimental effect of multiple light scattering by combining the time-gated detection and spatial input-output correlation. In the present work, we perform a rigorous theoretical analysis on the effect of multiple light scattering to the optical transfer function of CASS microscopy. In particular, the spatial frequency-dependent signal to noise ratio (SNR) is derived depending on the intensity ratio of the single- and multiple-scattered waves. This allows us to determine the depth-dependent resolving power. We conducted experiments using a Siemens star-like target having various spatial frequency components and supported the theoretical derived SNR spectra. Our study provides a theoretical framework for understanding the effect of multiple light scattering in high-resolution and deep-tissue optical imaging

A diode-pumped Yb:Y

A Micro holes in a diamond are presented by using a homemade femtosecond (fs) Yb:KGW laser. An fs laser source was used emitting pulse duration of 230 fs at 1030 nm wavelength, whereas the spot size amounted to 8.9 μm. Parameters like pulse energy, and pulse number were varied over a wide range in order to evaluate their influence both on the micro hole geometry like hole diameter, circularity, taper angle, and on the drilling quality. Hourglass-shaped micro holes whose diameters decrease and increase again after a certain depth have important applications. The results demonstrate the feasibility of extending the drilling of an hourglass-shaped hole in a diamond sample, which has similar diameters at the hole entrance (92 μm) and exit (95 μm), but a much smaller diameter (28 μm) at a certain waist section inside the hole.

A key requirement for wearable electronics is an adequate and sustainable power source. Accordingly, a self-powering unit that replaces rechargeable secondary batteries is a promising solution. However, to realize permanent, maintenance-free, and highly durable wearable electronics, stretchable self-powering units that can harvest and store energy should be developed. In this study, we developed a fully stretchable self-charging power unit that integrates a micro-supercapacitor and triboelectric nanogenerator using oxidized single-walled carbon nanotube/polymer electrodes. The fully stretchable micro-supercapacitor with oxidized single-walled carbon nanotube/polyvinylalcohol electrodes exhibited a double layer capacitance of 20 mF cm−2 at 0.1 mA cm−2 and improved mechanical flexibility and stretchability over 10,000 cycles of stretching tests. A stretchable, polydimethylsiloxane-based current collector employing silver nanoparticles embedded with oxidized single-walled carbon nanotubes enabled the fully stretchable, freestanding-triboelectric-layer based nanogenerators to produce a maximum instantaneous power density of 84.4 mW m−2 under periodic and round-trip sliding of a Nylon fabric while stretching up to 40% without significant performance degradation. Furthermore, a micro-supercapacitor of fully stretchable self-charging power unit could be successfully charged by the nanogenerator from 0 to 2.2 V in 1200 s and powered commercial digital clock for approximately 10 s. These results demonstrate that stretchable polymer composites with oxidized single-walled carbon nanotubes are suitable electrodes and active materials for fully stretchable and self-powered wearable electronics.

We present a hybrid chirped pulse amplification femtosecond laser amplification system with which to realize a Yb:KGW regenerative amplifier (RGA) and a Yb:YAG thin-rod amplifier. The combination of RGA based on dual Yb:KGW crystals and a thin-rod Yb:YAG amplifier with a high gain brings about output power up to 46 W before and 29.2 W after pulse compression down to 277 fs at a repetition rate of 200 kHz. The gain-narrowing effect was complemented by a combination of different types of gain-medium amplification. The results show that the output power of a Yb:KGW-based amplifier can be amplified simply by using a Yb:YAG thin-rod amplifier while suppressing the broadening of the pulse duration by gain narrowing.

We investigate experimentally and theoretically the band structure of the (In0.53Ga0.47As)1−z (In0.52Al0.48As) z digital alloy grown by using molecular beam epitaxy as a function of z, where z is defined by the thickness fraction of the InGaAs and the InAlAs layers lattice-matched to InP. To calculate the band structures of the InGaAs/InAlAs digital alloy, we used the 4 × 4 k·p method; then, we compared these band structures with the photoluminescence experimental results. These experimental and theoretical results show that the InGaAs/InAlAs digital alloy not only can contribute to the method of band-gap engineering by using various types of thickness combinations but also can cover the wavelength gap of 1.2 μm (1.1 μm (GaAs) < λ < 1.3 μm (InP)), that only the quantum dot can cover. We also propose a quantum-well structure that is able to cover the wavelength gap.

Compared with the traditional sinusoidal voltage source, a short rising nanosecond voltage source can generate a high electron current for a short rising time. This paper investigates how the nanopulse parameters such as the voltage amplitude, pulse duration, and repetition frequency affect the radical generation and the plasma bullet propagation in an atmospheric pressure helium plasma jet. An intensified charge-coupled device was used to observe the bullet propagation in the nanosecond gate mode. The plasma bullet’s propagation speed is mainly affected by the applied voltage and externally biased electrodes rather than the pulse duration or the driving frequency. In contrast, optical emission spectroscopy diagnostics estimate that the radical density inside the atmospheric pressure plasma jet mainly increases with the repetition frequency. At the same time, the population of high-energy electrons can be controlled with the unipolar voltage amplitude. Thus, unipolar nanosecond pulses make it possible to control the emitting charges and the generated radicals independently.

We have studied experimentally a high power booster of Yb:YAG single-crystal fiber with regenerative amplifier based on dual-slab Yb:KGW crystals. The booster provided the output power of 45 W with the gain of 3. It allowed the laser system to maintain the spectral bandwidth.

This paper proposes a gate driver circuit for short pulse generation in solid-state pulsed power modulators. The proposed circuit effectively drives high-side switches by implementing an isolated voltage source with a diode and capacitor at each secondary side of a multi-winding transformer. In addition, since it applies voltages to the transformer primary side for a short time, the gate signal with long duty cycle can be produced without the transformer saturation problem. Moreover, by employing the positive and negative voltages asymmetrically, the proposed circuit can generate a short gate signal while supplying sufficient energy to drive semiconductor switches. Experimental results from a 2kV solid-state pulsed power modulator are presented to verify the proposed work.

The numerical model for simulation of broadband amplification in a thin-rod and a tapered rod active elements was developed. The simulation results verified by the experimental data

Hybrid Yb:Y 2 O 3 ceramic thin-rod femtosecond amplifier is reported. By 4-pass amplification scheme, output power of 1.4 W with gain of 14 is achieved from 100 mW, 1033 nm, 30 MHz fiber seeder. The extracted gain spectrum shows gain bandwidth of about 5.0 nm centered at 1030.6 nm.

High-power femtosecond (fs) lasers in the visible wavelength regime have numerous applications in areas including micro-machining, medical eye surgery, communication, spectroscopy, etc. To generate this laser beam, frequency conversion, especially second-harmonic generation (SHG), of near-IR lasers using nonlinear optical crystals is known to be the most standard technique. However, the use of a long-length crystal, which is preferred to achieve high SHG conversion efficiency for long-pulse or cw lasers, cannot be applied to the fs laser with broad linewidth due to the tight phase matching condition and the exacerbated walk-off effect. Thus the conditions of the nonlinear optical crystal should be optimized to achieve efficient SHG generation and hence, the high power visible fs laser pulses. There are many reports for the efficient SHG of the fs lasers but not many reports about influence of the crystal length on the SHG process, such as the pulse width and the linewidth and the conversion efficiency. Here, we report efficient SHG of femtosecond Yb lasers at 1 um by optimizing the conditions of nonlinear optical crystals. The SHG pulse and the conversion efficiency were numerically calculated to find the optimized conditions of the nonlinear optical crystals for the high power fs laser pulses with different pulse widths. Preliminary experiments were conducted using a Type I LBO crystal and the femtosecond Yb laser at 1 um, which was in good agreement with the theoretical results. The theoretical and the experimental results for LBO and BBO crystals will be reported in detail.

Diode-pump absorption is experimentally studied in a high-power Yb:KGd(WO4)2 (Yb:KGW) laser in the presence and absence of lasing. The maximum absorption efficiency in the cw regime exceeds 77% which is by a factor of 1.4 greater than the maximum absorption efficiency in the absence of lasing. The powers of thermo-optical lenses induced in laser crystals during lasing are measured. A strong dependence of the lens power and aberrations on the orientation of laser crystals relative to the propagation direction and polarisation is confirmed.

A diode-pumped Yb:Y2O3 ceramic thin-rod amplifier which operates in the femtosecond regime is studied here. In a single-stage and direct four-pass amplification scheme, the amplifier delivers maximum output power of 8.1 W at a center wavelength of 1030.5 nm and spectral bandwidth of 4.8 nm. Assume a sech2-shaped pulse, a pulse duration of 239 fs is measured, exhibiting a time-bandwidth product value of 0.324. To the best of our knowledge, our Yb:Y2O3 ceramic thin-rod femtosecond amplifier exhibits the shortest pulse duration with Watt-level output power among all Yb:Y2O3-based femtosecond amplifiers.

We have studied self-action effects (self-focusing and self-phase modulation) and stimulated Raman scattering in an Yb : KGW chirped-pulse amplification laser system. The results demonstrate that self-focusing in combination with thermal lensing may significantly limit the chirped pulse energy in this system (down to 200 μJ) even at a relatively long pulse duration (50 ps). Nonlinear lenses in the laser crystals in combination with thermal lenses bring the regenerative amplifier cavity in the laser system to the instability zone and limit the average output power at pulse repetition rates under 50 kHz. Self-phase modulation, a manifestation of self-action, may significantly distort a recompressed femtosecond pulse at energies near the self-focusing threshold. Stimulated Raman scattering in such a laser has a weaker effect on output parameters than do self-focusing and thermal lensing, and Raman spectra are only observed in the case of pulse energy instability.

This paper discusses a high voltage pulsed power modulator with high reliability and fast switching speed for medical lasers. The proposed circuit can improve reliability by employing a modular structure using bypass devices. Furthermore, since the developed pulsed power modulator utilizes metal oxide silicon field effect transistors (MOSFETs) as bypass devices as well as main switches, it can achieve fast switching speed. Experimental results from a 1 kV and 300 kHz pulsed power modulator is shown to verify the proposed work.

Numerical simulations and laboratory experiments are conducted for the development of a compact femtosecond diode-pumped Yb:KYW oscillator. For optimizing the oscillator as a seeding source for a regenerative amplifier, we simulated the output power as a function of the transmission of the output coupler, the incident pump power, and the amplification axis of the gain medium by using laser cavity analysis and design (LASCAD) software. Numerical and experimental results show good agreement for both N p - and N m -polarization for N g - and N p -cut crystals. The experimental results show that the N m -polarization oscillator’s average power exceeds 1.2 W at the central wavelength of 1035 nm with a pulse duration 111 fs, which is suitable for the combined gain spectrum of a dual-crystal amplifier.

End-diode-pumped lasers based on one and two Yb : KYW crystals operating in cw and Q-switched regimes, as well as in the regime of mode-locking, are studied. The single-crystal laser generated stable ultrashort (shorter than 100 fs) laser pulses at wavelengths of 1035 and 1043 nm with an average power exceeding 1 W. The average output power of the two-crystal laser exceeded 18 W in the cw regime and 16 W in the Q-switched regime with a slope efficiency exceeding 30 %.

We have studied synchronous behaviors between a diode-laser-pumped Nd:YAG laser and an electronically-implemented Rossler oscillator. When the Rossler oscillator is unidirectionally coupled to the Nd:YAG laser, two chaotic systems develops from a non-synchronous state to a phase synchronization state with a π phase shift through a 2π phase jump state as the coupling strength increases. To verify that the π phase shift is not anti-phase synchronization but phase synchronization(PS) with a π phase shift, we propose two kinds of similarity functions. From the similarity functions, we confirm that the synchronous phenomenon is PS with a π phase shift.

A Doppler ultrasound transducer was designed and implemented to measure the blood flow velocity in tiny vessels near the skin of hands or feet. The geometric parameters of the transducer for defining the observation volume were derived and implemented with an acoustic window made of polystyrene. The observation volume designed in this study was located 6.5 mm from the transducer, which was comparable to the value predicted geometrically. The two-way insertion loss of the transducer was 11.3 dB on ultrasound frequency of 20 MHz, and the 3-dB bandwidth was approximately 2 MHz. In addition, the Doppler shift in the frequency measured by using a Doppler device composed of the transducer and a Doppler signal processing unit was proportional to the flow velocity generated by a homemade flowing system. Finally, we concluded that the transducer could be applied to measure the blood flow velocity in hands or feet.

Both direct- and evanescent-field interactions with carbon nanotubes (CNTs) are applied to achieve stable Q-switched operation of Yb:KYW planar waveguide lasers. The performance characteristics were investigated in a same cavity configuration and analyzed in detail in the following three cases, CNTs deposited onto end mirror (M-coating), output coupler (OC-coating) and top surface of the planar waveguide (WG-coating). Maximum output powers, repetition rates, and minimum pulse durations are 61 mW, 1103 kHz and 215 ns for OC-coating, 39 mW, 1052 kHz and 275 ns for WG-coating, and 26 mW, 1119 kHz and 217 ns for M-coating, respectively. From the calculation of the configuration-dependent stability range, the beam size and the electric field distribution in the Yb:KYW planar waveguide, it is confirmed that the evanescent-field interaction scheme makes stable Q-switching possible with much lower intensities at saturable absorber compared to the direct-field interaction scheme in the presented waveguide laser operation.

A number of femtosecond laser systems have been created based on the amplification of chirped and supershort pulses and implemented in broadband ytterbium-doped laser gain media (Yb:KGW and Yb:YAG) with direct laser diode pumping. The use of various active element geometries in the form of thin plates and thin rods makes it possible to obtain pulses with an average radiation power of 10–100 W. The quality of the laser beam is close to that of a diffraction-limited beam. All of these parameters allow the use of laser systems developed for various technological and biomedical applications requiring high-precision laser exposure.

This work was supported by the Korea Electrotechnology Research Institute Primary research program (18-12-N0101-41) through the National Research Council of Science and Technology (NST) funded by the Ministry of Science, ICT and Future Planning (MSIP) and the Basic Science Research Program (NRF-2017R1A2B4005806) funded by National Research Foundation of Korea (NRF).

A numerical model for simulation of broadband amplification in a thin rod and thin-tapered-rod active elements was developed. The amplification of ultrashort laser pulses in three gain modules of different geometries was studied experimentally; the results of the experiments were used for validation of the elaborated numerical model. A laser system consisting of an ultrafast solid-state master oscillator and a two-stage thin-rod amplifier was constructed. With the use of the developed numerical model, optimization of the active elements’ parameters was carried out in order to increase the output power of the elaborated laser system.

A femtosecond laser based on an Yb:KYW crystal with direct longitudinal pumping by a high-power semiconductor injection laser with a fiber output is described. Femtosecond pulses were generated in the self-longitudinal-mode-locking operating condition due to the use of a semiconductor saturable absorber. The average power of the oscillator was as high as 3.5 W at a central wavelength of 1035 nm, the pulse length and pulse repetition rate being 200 fs and 85.5 MHz, respectively. The product of the pulse length and the radiation spectrum width was 1.3 times higher than the theoretical limit for the pulse shape described by the function sech2. The designed master oscillator can be also used as a stand-alone source of femtosecond radiation pulses for material microprocessing and primary source for femtosecond laser amplification systems.

The thermo-optical effects in the diode-end-pumped lasers with Yb:KGW anisotropic crystals is experimentally investigated. Strong dependence of optical power and aberrations of the lenses on orientation of laser crystals concerning a direction of laser radiation propagation and a polarization direction is confirmed. By optimizing the crystal configuration we obtained a high-power output laser beams with the high spatial quality M2 close to unit in Q-switched mode and at regenerative amplification of chirped pulses.

Characterizations of the high-density gas jets are performed for the laser–gas interaction. It is shown that the gas density profile can be obtained without the Abel inversion, when a Gaussian distribution is assumed. In addition, a rectangular nozzle is characterized for the long plasma generation. In this case, the Boltzmann distribution is introduced for the density profile and its result shows a good agreement with the experimental result.

Self-injection mechanisms in the self-modulated laser wakefield acceleration (SM-LWFA) are investigated. Two-dimensional (2D) particle-in-cell (PIC) simulations show that a significant amount of plasma electrons can be self-injected into the acceleration phase of a laser wakefield by a dynamic increase in the wake wavelength in the longitudinal direction. In this process, it is found that the wake wavelength increases due to the relativistic effect and this leads to a large amount of electron injection into the wakefields. In this paper, the injection phenomena are studied with 2D simulations and a brief explanation of the new self-injection mechanism is presented.

A semi-analytic model of collisionless sheath in plasma immersion ion implantation (PI/sup 3/) for a step bias with finite rise time in cylindrical geometry has been developed. The model takes into account the formation of the presheath, predicts the sheath overshooting and its further recovery to the steady-state Child value. To verify the model, a sheath dynamics has been investigated experimentally on a 30-kV PI/sup 3/ setup using the positively biased Langmuir probe technique. The measurements have been carried out in argon and helium plasmas of inductively coupled and hot cathode plasma sources. The model predictions agreed well with the experimental results.

We demonstrate a femtosecond Cr:YAG laser mode-locked by a carbon nanotube saturable absorber mirror (CNT-SAM) at a repetition rate of 550 MHz. By employing the CNT-SAM, which exhibits a modulation depth of 0.51% and a saturation fluence of 28 μJ/cm2 at 1.5 μm, we achieved a compact bulk Cr:YAG laser with self-starting mode-locked operation near 1.5 μm, delivering an average output power of up to 147 mW and a pulse duration of 110 fs. To our knowledge, this system provides the highest repetition rate among reported CNT-SAM mode-locked Cr:YAG lasers and the shortest pulse duration among saturable absorber mode-locked Cr:YAG lasers with repetition rates above 500 MHz.

Sensing and manipulating targets hidden under scattering media are universal problems that take place in applications ranging from deep-tissue optical imaging to laser surgery. A major issue in these applications is the shallow light penetration caused by multiple scattering that reflects most of incident light. Although advances have been made to eliminate image distortion by a scattering medium, dealing with the light reflection has remained unchallenged. Here we present a method to minimize reflected intensity by finding and coupling light into the anti-reflection modes of a scattering medium. In doing so, we achieved more than a factor of 3 increase in light penetration. Our method of controlling reflected waves makes it readily applicable to in vivo applications in which detector sensors can only be positioned at the same side of illumination and will therefore lay the foundation of advancing the working depth of many existing optical imaging and treatment technologies. (C) 2015 Optical Society of America

Two-dimensional slices of the cross-sectional distributions of fuel images in the combustion chamber were visualized quantitatively using a laser-induced exciplex fluorescence technique. A new exciplex visualization system consisting of 5% N,N-dimethylaniline (DMA)5%1,4,6-trimethylnaphthalene (TMN) in 90% isooctane (2,2,4-trimethylpentane) fuel was employed. In this method, the vapor phase was tagged by the monomer fluorescence while the liquid phase was tracked by the exciplex fluorescence with good spectral and spatial resolution. The 308 nm (XeCl) line of an excimer laser was used to excite the doped molecules in the fuel and the resulting fluorescence images were obtained with an intensified charge coupled device (ICCD) detector as a function of time. The results demonstrate that at the end of the compression stroke, the liquid fuel was almost vaporized and a dense stratified vapor phase charge developed near the two spark plugs.

We present a results of dual-crystal Yb:KGW laser development that is capable to operate as a actively Q-switched oscillator with output power up to 24 W and pulse length of 20 ns, or as a regenerative amplifier with output power up to 21 W and pulse duration below 200 fs after compression of chirped pulses. Both lasers have excellent beam quality with beam parameter M

We report on experimental investigations of nonlinear propagation of an array of first-order phase singularities with the same charges, which is lining up in a straight line, through a self-defocusing medium. The nonlinear rotation of the singularities depends on their density and is not uniform for each singularity pair. We discuss the non-uniform rotation considering singularity–singularity interaction.

We report a diode-pumped Yb:KGW laser that is capable of operating as a Q-switched oscillator or as a regenerative amplifier with average power of more than 20 W. The laser is based on a dual-crystal configuration where the pump thermal load is distributed over relatively long two crystals. It permits a sufficiently large number of passes with low passive losses and maximizes the energy extraction efficiency. The amplification bandwidth was extended by spectral combining of two Yb:KGW crystals with spectrally shifted gain maxima, that allows to mitigate spectral gain narrowing and provides pulse length down to 200 fs after compression in a stretcher-compressor module. The output power saturated with increasing pump power and output beam quality was defined by aberration of thermal lenses. Optimization of laser cavity allows us to compensate thermal lens partially and provide output beams with quality M2

A temperature measurement scheme was proposed in a diode end-pumped thin monolithic Yb:YAG laser by analyzing the red-shifting behaviors of each lasing peak. The amount of peak shift was measured on the basis of the threshold lasing spectrum by using a chopped pump beam. In order to determine the effective scale factor, the ratio between the peak shift and the temperature rise, the dynamics of the spectral shift, the output beam profile, and the output power were investigated. The effective scale factor was determined to be about 0.0114 nm/°C in the case of the crystal sandwiched by copper bocks with a hole, wherein the plane stress approximation is valid. On the other hand, the effective scale factor significantly decreased in the case of the crystal sandwiched by sapphire plates.

The propagation properties of three-dimensional dark spatial solitons having odd ring formation is analyzed numerically in the frame of the (1 + 2)-dimensional nonlinear Schrodinger equation and compared with a pair of odd dark solitons. We discuss the experimental excitation condition of an odd ring dark soliton, which is superimposed on a finite-width background beam, with phase masks.