This PDF file contains the front matter associated with SPIE Proceedings Volume 8702, including the Title Page, Copyright Information, Table of Contents, and the Conference Committee listing.

The paper presents a current state of the project aiming to develop a compact and mobile pulsed laser source, operated in “eye-safe” spectral region (1.5 μm). It will be a high power, all-fiber system generating nanosecond pulses with repetition rate ranging from tens to hundreds kHz and built in Master Oscillator Power Amplifier (MOPA) configuration. First amplifying cascade of the system has been developed. Distributed Feedback (DFB) laser diode with home-built supply and pulse control system was used as a master oscillator. It can generate rectangular laser pulses with independently changeable repetition rate (10 – 200 kHz) and pulse width (20 – 300 ns). The system provides over 34 dB optical gain. In addition, simulations of amplification laser radiation in the active fiber for different input pulse energies in relation to saturation energy were presented. Furthermore theoretical and experimental optimization of an active fiber length was done. In the first elaborated stage of amplifier 18,1 % slope efficiency was obtained.

ε Broadband and spectrally flat supercontinuum (SC) generation in standard single-mode passive and Tm-doped fibers pumped by 1.55 μm pulses in the anomalous dispersion region is presented. Initial results on SC generation in a singlemode fluoride fiber are also presented. Using only a piece of commercially available SMF-28 as a nonlinear medium, the SC covering the spectral range from ~1.3 μm to 2.5 μm with the mean power of 1.71 W and a 5 dB spectral flatness of 640 nm is reported. When pumping a piece of Tm-doped fiber, the spectrum spreading from ~1.4 μm to 2.65 μm with its significant part located over 1.8 μm wavelength was recorded. SC generated in a fluoride fiber spread from ~0.9 μm to 3.2 μm with the average power of 0.85 W (out of which, over 0.1 W was located beyond 2.4 μm) was achieved. εε

A splicing procedure of erbium doped fiber with standard SMF-28e is discussed in the paper. The optical loss of 0.12 dB at 1300 nm wavelength was obtained. The active power monitoring method was adopted in the splicing process. Furthermore, the shape deformation of the octagonal, double clad fiber is reported. In addition, end-cap fabrication and angled fiber cleaving is discussed in the paper. Splicing and end-cap fabrication was performed with the use of filament fusion splicer.

Method of spectroscopy m-line is an accurate method for determination of the optical parameters of the planar and stripe waveguides. In this method, the laser beam is coupled to the waveguide (e.g. by the prism) in the form of discrete angles. If the layer of the solid or liquid material is deposited on the waveguide, the change in the coupling angle is observed. Modified method of the m-line spectroscopy allows for determination of the optical parameters of deposited layers with high accuracy. Moreover, modification of the waveguide structure obtained via deposition of consecutive layers and changes the ability to propagate not only in the same waveguide. Modified method of m-line spectroscopy has found many potential applications in various areas such as: technological control of the applied layers quality; modification of the light propagation in the waveguide structures; utilization in the preventive medicine for diabetic diseases; food-control of the level of nutrients in vegetables (e.g. sugar level in white beets).

The novel scheme of self-adaptive, closed-loop resonator of diode-side-pumped Nd:YAG slab laser was presented. The dynamic holography principle was exploited to spatial cleaning of the laser mode. The phase conjugate mirror was created inside the gain medium as a result of four-wave mixing of resonator standing waves intersecting at a small angle. The output beam was extracted from the cavity as a 1-st diffraction order of laser mode interacting with the dynamic gain gratings created inside active medium. The near diffraction limited (parameter M²=1.2) output beam with 250 mJ of energy at repetition rate up to 25 Hz in free running regime was achieved. Any spectral narrowing effects were not observed.

Carrier transport and optical properties of optically pumped vertical-external-cavity surface-emitting lasers (VECSELs) have been analyzed with the aid of the self-consistent numerical model. An influence of active-region design parameters, such as its length as well as number and arrangement of quantum wells, on a carrier distribution and material gain has been investigated. Moreover, a performance of various structures has been compared with the aid of a simple optical model. In particular, increasing number of quantum wells has been found not always to lead to an increasing maximal output power. An arrangement of quantum wells is also of importance. For example, quantum wells located in long active regions far from a chip surface can be not sufficiently pumped. Numerical models described in this paper may give an opportunity to understand more deeply details of VECSEL operation and to design optimal laser structures.

Using a Vertical Cavity Surface Emitting Laser (VECSEL) “as-grown” heterostructure we set-up a laser emitting at 488 nm with the output power approaching 20mW. The short wavelength emission was due to the conversion of the 976nm emission by a second harmonic generation process in a type-I lithum triborate (LBO). The V-type external cavity permitted efficient focusing of the laser beam on both the VECSEL heterostructure and the non linear crystal. A small diameter focused spot on the gain mirror is required when “as-grown” heterostructures are used. No birefringent filter was used in the resonator. In the case of our heterostructure we observed that the light was spontaneously polarized along the one of the crystallographic direction. The polarization ratio was 1000:1. The VECSEL heterostructure was of the resonant type strongly enhancing a single wavelength emission. The wavelength fine tuning was performed by heatsink temperature adjustment. The heterostructure was grown by molecular beam epitaxy. It consisted of 12 InGaAs quantum wells enclosed by GaAs barriers and a AlAs/GaAs DBR.

Low quality of the optical beam emitted by high-power laser diodes is the main disadvantage of these devices. The two most important reasons are highly non-Gaussian beam profile with relatively wide divergence in the junction plane and the filamentation effect. Designing laser diode as an array of narrow, close to each other single-mode waveguides is one of the solutions to this problem. In such devices called phase locked arrays (PLA) there is no room for filaments formation. The consequence of optical coupling of many single-mode waveguides is the device emission in the form of few almost diffraction limited beams. Because of losses in regions between active stripes the PLA devices have, however, somewhat higher threshold current and lower slope efficiencies compared to wide-stripe devices of similar geometry. In this work the concept of the high-power laser diode resonator consisted of joined PLA and wide stripe segments is proposed. Resulting changes of electro-optical characteristics of PLA are discussed. The devices are based on the asymmetric heterostructure designed for improvement of the catastrophic optical damage threshold as well as thermal and electrical resistances. Due to reduced distance from the active layer to surface in this heterostructure, better stability of current (and gain) distribution with changing drive level is expected. This could lead to better stability of optical field distribution and supermodes control. The beam divergence reduction in the direction perpendicular of the junction plane has been also achieved.

The laser diodes (LD) have numerous applications and promise to become key elements for next generation laser technologies. LD are usually operated under conditions of heavy thermal load. As a result, the devices are affected by aging processes leading to changes of the operation parameters, degradation and, eventually, complete failure. Degradation of high power semiconductor lasers remains a serious problem for practical application of these devices. We investigated the effect of mounting induced strain and defects on the performance of high power laser. In this paper measurements of the temperature distribution and the electroluminescence along the cavity of InGaAs quantum well lasers before and after accelerated aging processes are presented. The electro-optical parameters of the high output power laser diodes, such as emission wavelength, output power, threshold current, slope efficiency, and operating lifetime are presented too.

This paper shows results obtained by simplified thermal modeling of one-dimensional laser arrays designed based on a single InGaN edge-emitting laser diode. Laser arrays were designed using 2 – 7 emitters with a pitch ranging from 10 μm to 70 μm. Heat flux calculations using three-dimensional finite-element analysis have been undertaken for the evaluation of efficiency of diamond heat spreader applied to these devices. An impact of size (thickness, length, width) of diamond heat spreaders on maximal temperature increase in active region of designed epi-up and epi-down laser diode arrays has been determined.

The paper presents results of experimental investigations of spatial distribution of radiation emitted by quantum cascade lasers. Measurements have been performed by means of a unique goniometric profilometer specially de- signed for the large angle laser beams. The advantages and limitations of the set-up and the applied experimental method are discussed. The obtained results have enabled the analysis of dependence of geometry of the beam on the geometry of the laser structure and on the mount method of the laser chips. The angular divergence of the beams has also been tested as a function of laser power supply.

AlGaAs/GaAs quantum cascade lasers are coherent electromagnetic wave emitting sources operating in the mid and far infrared. They provide large optical power and are characterized by small sizes. Unfortunately, partly because of their large thermal resistivity they need to be powered by pulsed generators witch provide high current value and have small rise and fall times. A solution of this disadvantage is presented in this paper as a programmable regulated current source ZS62 that uses a novel way to generate ultra fast current pulse and has its own dedicated software.

Quantum cascade lasers (QCL’s) have proven their usefulness as light sources in many applications, like remote gas sensing, molecular spectroscopy or free-space communication. In most cases the high-quality low-divergence beam is desired. This work presents the theoretical analysis of QCL’s beam divergence. The electromagnetic field in the resonator is calculated according to effective index method. Theoretical results are compared with measurements.

In this work we demonstrate a harmonically mode-locked Er-doped fiber laser utilizing graphene saturable absorber. The laser could operate at various harmonics of the fundamental repetition frequency, depending on the launched pump power. The highest obtained repetition rate was 2.22 GHz, which corresponds to the 21st harmonic of the resonator mode-spacing. At this harmonic, the laser generated sub-picosecond pulses with over 40 dB of supermode noise suppression. Multilayer graphene was obtained by mechanical exfoliation and deposited onto a fiber connector tip, forming a saturable absorber.

Mechanically exfoliated graphene saturable absorber based all-polarization maintaining passively mode-locked erbium doped fiber laser is presented. The laser consists of fully polarization maintaining (PM) fibers and components, providing linear output polarization state. The saturable absorber was formed by mechanical exfoliation of graphene flakes from pure graphite and deposited on a fiber connector. It was characterized using atomic force microscopy and Raman spectroscopy. Laser resonators with repetition frequency of 45.88 MHz and 114.1 MHz were investigated. The soliton pulses at 1555 nm were achieved with duration around 600 fs. The splicing procedure of PM-fibers was also optimized which results in improvement of degree of polarization (DOP).

A new design of an erbium-ytterbium doped fiber amplifier is demonstrated. The amplifier contains a wavelength-tuned loop resonator for the 1 μm signal. The amplified spontaneous emission (ASE) from Yb ions is used to stimulate a laser emission at several wavelengths from the 1 μm band in the 1550 nm amplifier. The wavelength of this lasing is selected by introducing a spectral filter. The results show, that the efficiency of the amplifier at nominal 1550 nm wavelength can be increased by introducing a feedback loop with 1040 nm and 1050 nm filters. This loop also protects the Er-Yb amplifier from parasitic lasing and allows output power scaling without risk of self-pulsing at 1 μm.

In this paper we present a device - fiber based coherent light source operating at 1550 nm wavelength and 5 W of the output power. It is made completely of the fiber elements without any bulk optics therefore it is stable and resistant to the environmental conditions. The main idea was to use so called MOPA (Master Oscillator Power Amplifier) configuration to obtain universal design. Thus the device can be easily configured to work in couple different operation regimes.

Pulsed thulium-doped silica fiber laser operating at a wavelength of 1994.8 nm was developed. The laser was fast gain-switched by 1.55-μm radiation generated from a fiber amplifier system seeded by a directly modulated distributed feedback semiconductor laser. The Tm-doped fiber laser delivered stable nanosecond pulses at a repetition rate ranging from 50 kHz to 300 kHz. The maximum average output power as high as 1.08 W with a slope efficiency of 49% for the repetition rate of 100 kHz was reported. The shortest stable pulses recorded had a width of (20-25) ns and the energy of <15 μJ. The laser system was developed in all-fiber architecture, thus providing robustness, compactness, high insensitivity to atmospheric conditions (dust, vibrations, humidity).

The paper presents a digest of chosen research centers, subjects and results in the domain of free electron lasers and accelerator science and technology in Europe. Some of these issues were shown during the annual meeting of the EU FP7 project EuCARD – European Coordination of Accelerator Research and Development (2009-2013) [13-14]. The project concerns building of the research infrastructure, including in this advanced photonic and electronic systems for servicing large high energy physics and FEL experiments. There are debated a few basic groups of such infrastructures, networks and systems like: POLFEL, FLASH, SPARC, LIFE, CFEL, IRFEL, IRVUX, ELBE, FELIX, LCLS, E-XFEL along with some subsystems like seeding lasers, beam diagnostics, high field magnets, superconducting structures, multichannel measurement – control networks for FELs for large amounts of metrological data acquisition, precision photonic networks of reference time, frequency and phase distribution. A digest of references on FEL and HEP was included [1-133], with emphasis on work in Poland on the Polfel project.

Time evolution of the laser light intensity from a self-starting Yb:KYW femtosecond laser with passive mode-locking is presented. One photon and two photon signal transients have been recorded for a few hundred microseconds after opening the laser cavity, and transition from continuous wave to pulsed operation is observed. The collected data are divided into two common types of evolution, with different transition phases and their characteristics are discussed.

Argon ion lasers can generate several strong laser lines in short wavelength region of visible spectrum (green and blue light). Krypton ones offer the generation of laser lines in long wavelength region (red and yellow light). Both gases have complementary generation ranges thus ion lasers filled with mixture of argon and krypton are attractive laser sources for many applications. In most of these applications the only one laser line selected with dispersion element within the resonator are used at one time. After removing the dispersion element the simultaneous generation of many wavelengths is possible. Unfortunately in this working mode of ion lasers the negative effect of competition between laser lines appears. The effect has the most significant influence on the generation of yellow Kr II 568 nm line which is very needed for some applications due to small number of other available strong laser sources for this light range. Generation conditions of this line is strongly hampered when ion laser simultaneously generates other laser lines thus in this laser working mode this laser line completely disappears. We have observed the exact reason of this effect and we have described the way to improve laser generation conditions of Kr II 568 nm line which makes possible to obtain the laser generation of this line simultaneously with other laser lines.

In the previous our paper we have presented measurement results of the phenomenon of argon additions influence on output parameters of krypton ion lasers. In that paper we have described that small argon admixtures to the krypton discharge increase the laser output power of several krypton laser lines. In actual paper we present following measurement results of this phenomenon. We have observed that neon admixtures cause much stronger effect on krypton laser lines than we have previously observed with argon admixtures. We have also observed the positive influence of neon additions on generation conditions of argon laser lines. The magnitude of this effect is weaker than influence observed with krypton laser lines however the way of the effect is identical. This confirms our explanation of this phenomenon described in. Results presented in actual paper were performed in wide range of mixture compositions, gas pressures and discharge current values for several argon and krypton laser lines.