Global Dynamic Monitoring and Security Network (GDMSN) for real-time monitoring of (1) environmental and atmospheric conditions: chemical, biological, radiological and nuclear hazards, climate/man-induced catastrophe areas and terrorism threats; (2) water, soil, food chain quantifiers, and public health care; (3) large government/public/ industrial/ military areas is proposed. Each GDMSN branch contains stationary or mobile terminals (ground, sea, air, or space manned/unmanned vehicles) equipped with portable sensors. The sensory data are transferred via telephone, Internet, TV, security camera and other wire/wireless or optical communication lines. Each sensor is a self-registering, self-reporting, plug-and-play, portable unit that uses unified electrical and/or optical connectors and operates with IP communication protocol. The variant of the system based just on optical technologies cannot be disabled by artificial high-power radio- or gamma-pulses or sunbursts. Each sensor, being supplied with a battery and monitoring means, can be used as a separate portable unit. Military personnel, police officers, firefighters, miners, rescue teams, and nuclear power plant personnel may individually use these sensors. Terminals may be supplied with sensors essential for that specific location.
A miniature "universal" optical gas sensor for specific applications in life support and monitoring systems was designed and tested. The sensor is based on the physics of absorption and/or luminescence spectroscopy. It can operate at high pressures and elevated temperatures, such as in professional and military diving equipment, submarines, underground shelters, mines, command stations, aircraft, space shuttles, etc. To enable this capability, the multiple light emitters, detectors and data processing electronics are located within a specially protected chamber.
A new generation of the optical fiber catheter has been developed for surgical treatment of atrial fibrillation with laser
radiation. Atrial fibrillation (AF) is a heart rhythm abnormality that involves irregular and rapid heartbeats. The surgical
maze procedure was the first treatment that offered a permanent solution for maintaining a normal sinus rhythm in
patients with AF. This procedure involves the creation of a maze-like series of incisions in the left atrium, resulting in
isolation of the pulmonary vein and removal of the left atrial appendage. To produce long continuous transmural lesions
laser diodes operating in near IR range along with end-emitting fiber catheters have been used experimentally. The
absence of side-emitting flexible catheters with the ability to produce long continuous lesions limits the further
development of this technology. In this research, a new type of an optical catheter consisting of a flexible, spatially
modulated fiber diffuser has been used to make continuous photocoagulation lesions for effective maze procedure
A new architecture of single-frequency high efficiency mini-solid-state lasers is proposed. The application of a
metallic nano-film selector has been investigated theoretically and experimentally. It has been shown that a cobalt thinfilm
selector with a thickness between 8 and 10 nm provides a single- frequency output within a power range of up to 0.6
W with a 1-mm thick Nd:YVO4 gain crystal. At single-mode operation, it accumulated 85% of the multimode laser
output. Slope efficiencies of single-frequency oscillation from 41% to 53% have been demonstrated for different
crystals. The output coupler movement by piezoceramic transducer provided single-frequency operation, with slow
smooth tuning, or chirping. The laser, with a cavity length less than 1", provided smooth tuning up to 10 GHz, frequency
chirping up to 4 GHz with a repetition rate of about 0.5 kHz, and hop tuning over 150 GHz at a maximum pump power
of 1.8 W. Double-frequency operation with a separation of 1.5 to 2.5 GHz was realized in a laser with a cavity length up
to 100 mm. Physical and technical limitations caused by the wide-gain bandwidth, thermal effects, and mechanical
vibrations of the cavity elements are discussed. The new specific regime of frequency self-stabilization provided with a
thin-film metallic selector has been proposed. Slow, periodical self-modulation phenomena in the diode-pumped singlefrequency
Nd:YVO4 laser with a cobalt thin-film selector have been demonstrated. Pulses with duration of about l to 3s
and periods of about 3 to 10 s have been observed.
Routinely used erbium crystal lasers operate at the 3-μm spectral range. In the silica fibers the transparency window corresponds to the eye-safe range of 1.5-μm. The 4I13/2 -4I15/2 transition provides the lasing at this range in a glass matrix. However, in crystals it is of negligibly small intensity. To significantly intensify this transition, the (Gd,Y)3(Ga,Sc)5O12:Er3+ crystal has been chosen as the basis for the new laser crystal that is able to operate at 1.5-μm. The single crystal garnet films with thickness up to 18-μm were grown, using the method of liquid-phase epitaxy on the Gd3Ga5O12 substrates. The 20-mol% maximal concentration of Er3+ ions was achieved without luminescence quenching. The up-conversion processes were blocked by the addition of the Fe-ions sensitizer. As a result, at the same level of absorbed pumping power the luminescence intensity at the 1.5-μm band for the specially doped film was approximately two orders of magnitude higher than that compared with the crystal of the traditional content. The spectral width achieved with a new medium is a little smaller than 300 nm, which makes this crystal convenient for the femtosecond laser design. The laser tunable inside this range may provide hundreds of the optical channels for telecommunication or optical computer devices.
Atrial fibrillation (AF) is a heart rhythm abnormality that involves irregular, and often rapid, heartbeats. Recent studies demonstrate the feasibility of treating AF and other structural heart diseases with limited, left-atrial ablation lesion sets. These cardiac ablation procedures reduce the time required to perform the maze procedure surgery, and are less invasive. To produce long continuous transmural lesions, solid-state lasers and high power laser diodes, along with end emitting fiber optic catheters, have been used experimentally. These devices demonstrated promising results, but the absence of side emitting fiber flexible catheters to produce long continuous lesions limits the further development of this technology. In this research, a prototype energy delivery and control system located in a catheter, was demonstrated. The highlight of the proposed system is a flexible 10-cm fiber diffuser that can be used to make continuous photocoagulation lesions for effective maze procedure treatments. The system also includes: a flexible optical reflector; a distributed temperature sensor array for monitoring the temperature in the surrounding tissue; a series of openings for rapid self-attachment to the tissue (vacuum holder - gripper); and an optional closed-loop irrigating chamber with circulating coolant to cool the optical diffuser.
A relatively cheap and compact deposition system, providing excellent high temperature superconducting films parameters, has been developed and studied. Y-Ba-Cu-O thin films were deposited routinely by the YAG double-laser system with the special optical beam and plasma plume shaping systems. Buffer CeO2 layers were deposited by the laser system as well. The properties of the plasma plume generated by the laser beam with a specific intensity distribution were investigated. A correlation between the superconducting film properties and the thermal schedule of the deposition process, the geometry of the set-up, the laser beam intensity distribution, the plasma plume shape and oxygen pressure has been found. Under optimal conditions Al2O3 - CeO2 - YBa2Cu3O7-δ - structures have provided the maximum critical current density of close to 107 A×cm-2 at 77 K in zero magnetic field. The films were used for the ultra high-frequency filters for the telecommunication devices.
The procedure of the non-Gaussian beam parameter measurement, evaluation and transformation are discussed. The beam structure of high power solid-state laser may be imagined as a superposition of several Gaussian-Schell beams with different polarization, divergence angles and waist diameters. An integrated parameter produce has been proposed to describe the complex beams.
A review of solid-state lasers used in optical metrology is presented. Various sources of laser parameters instabilities are discussed. Methods of laser output parameters stabilization are proposed. The solutions for Nd:YAG, Ti:sapphire, semiconductor, glass and fiber lasers are shortly presented and discussed. Possibilities and perspectives of use of different laser systems as standards for energy, power or frequency units are also shown.
A compact system for metrological use in the field of laser applications is presented. A new conception for a source of rectangular laser pulses within energy range of 1 nJ divided by 1 J and of 10-2 divided by 10-7 relative instability depending on pulse energy is proposed. The installation includes high stable, diode-pumped solid-state laser with a system for forming rectangular laser pulses that can be used as a standard for laser frequency, power, and energy in the near infrared range of spectrum.
Single frequency generation was investigated in two types of diode pumped lasers: microchips and lasers with metallic thin film selectors. Principles and properties of both types of single frequency generation are discussed. Energetic output characteristics, spectra of generation, tuning ranges were measured and compared for both lasers. In case of microchips only Nd:YAG crystal was applied, whereas in case of metallic thin-film selector single frequency output was achieved in Nd:YAG, Nd:YVO4 and Nd:YLF crystals. Up to 50 mW of power at single frequency in Nd:YAG microchip and 600 mW in Nd:YVO4 laser with selector were obtained. Physical and technical limitations caused by the wide gain bandwidth, thermal effects and mechanical vibrations were discussed.
Application of the metallic thin-film selector to tunable, single frequency oscillation of diode pumped lasers has been investigated theoretically and experimentally. Tunable, single frequency output was achieved in Nd:YAG, Nd:YVO4 and Nd:YLF crystals. The best results were obtained in case of Nd:YVO4 crystal namely up to 0.6 W output power for 2 W pumping laser diode with optical slope efficiency > 40 percent. Single frequency operation, slow smooth tuning or chirping within range 0.5-10 GHz was realized by means of output coupler movement with the piezoceramic transducer. In case of Nd:YLF crystal single frequency generation on both 1047 nm and 1053 nm lines was accomplished. Physical and technical limitations caused by the wide gain bandwidth, thermal effects and mechanical vibrations of cavity elements were discussed.
The review of novel solid state lasers for coherent optical velocimetry is presented. The paper is focused on laser diodes as well as diode pumped lasers as the most prospective sources nowadays and in the future in this area of applications. The single frequency diode pumped lasers are discussed in detail. The novel concepts in velocimetry such as chirped lasers, two frequency lasers, and lasers with self-mixing effect are presented. The applications of solid state lasers to Doppler velocimetry, holographic methods in velocimetry, and coherent laser radars are discussed.
The Nd:YAG and Nd:YVO4 crystals have been used as active media for single-frequency lasers. A thin metal film absorbing selector was used for single-frequency operation and fast tuning in the intermode range. The cavity optical length was variable in 10 - 60 mm range resulting in the frequency chirp of 1 - 6 GHz range.
A system with tunable cw-single-frequency master-YAG-laser and two Q-switched-slave lasers has been investigated. A thin-film absorbing selector has been used in the master laser. A computer-controlled piezo-ceramic driver provided tuning over 11 longitudinal modes, over 3 transverse modes, and frequency stability about 1 MHz per second. The minimum step in the back-loop system was 0.4 pm per 20 msec. A theory of active spherical cavity with thin-film selector has been developed. A optimum cavity configuration has been found.