Search

We have performed experimental and numerical studies enabling clear insight into the physical mechanisms underlying the super-mode noise mitigation in harmonically mode-locked (HML) fiber lasers using the resonant continuous wave (CW) injection. New experiments have refined the requirements to the positions inside the laser spectrum assigned to the injected CW component, a Kelly sideband, and the transparency peaks of the birefringent fiber filter. In particular, we have proved experimentally that the noise mitigation effect is dominating with the CW injected to the long-wavelength side of laser spectrum. Injection to the opposite side destroys the HML operation regime. Our numerical simulations confirm these specific features. To get the result, we have simulated phase-locking between the CW and a single soliton. Then, the developed model has been applied to the laser cavity operating multiple pulses in the presence of the gain depletion and recovery mechanism responsible for harmonic pulse arrangement. We clearly demonstrate how the CW injection accelerates or slows down the HML process enabling the generation of additional inter-pulse forces.

Melanoma is the most dangerous type of cancer, with a high rate of metastasis. The conventional method of treating skin melanoma is photodynamic therapy, yet this type of phototherapy has several side effects. In addition, the photosensitizers used are relatively expensive and toxic. Thus, developing methods of treating melanoma cancer using laser only is a promising area of research. Here we present in vitro effects in melanoma cell culture after 1265 nm laser irradiation exposure.

We report on a new, to the best of our knowledge, technique enabling fine-tuning of the pulse repetition rate (PRR) of a soliton harmonically mode-locked (HML) fiber laser built on the nonlinear polarization evolution (NPE). Optical injection of an external continuous wave (CW) into the HML laser cavity is used for this purpose enabling precise PRR tuning with the elementary step equal to the fundamental PRR one-by-one. The effect exhibits strong resonance dependence on the CW laser wavelength and available in both positive and negative directions. Our findings offer important insights into the HML laser dynamics associated with the birth and annihilation of solitons in the cavity.

Soliton fiber lasers with passive harmonic mode-locking (HML) have been known for several decades as reliable sources of pulse trains with a high repetition rate. They are commonly employed as frequency comb generators in a wide list of applications in spectroscopy, telecommunications, microwave photonics. Besides that exhibiting advantageous consumer properties, such as compactness, reliability, low cost and convenience of beam delivery approach these sources are among the most attractive alternatives for material processing, medicine lasers and other areas. In the first group of these lasers the HML occurs due to special intra-cavity periodic filter with a free spectral range (FSR) which is a multiple of the main cavity FSR and equals to the pulse repetition rate. The second group of HML lasers in this classification is attractive for the scientific community due to the automatic arrangement of strongly periodic pulse pattern in the laser cavity through pulse repulsion. However, it is difficult to specify the mechanism of pulse repulsion for each case. It can be based on interaction through saturating and relaxing dissipative parameters, continuous-wave (CW) radiation component, dispersion waves, or acoustic waves induced by electrostriction, etc. A common feature of all interaction induced effects is low intensity, in many cases only slightly exceeding the noise level. The noise-induced fluctuations in the time interval of the HML pulse train are known as HML timing jitter, and its value is significantly higher than the timing jitter in lasers operating at fundamental frequency. It is a major drawback of the HML laser technology. We report the stabilizing frequency shift effect in harmonic mode-locking ring soliton fiber laser that is studied theoretically and numerically. We demonstrate that the frequency shift contributes to an increase in the hardness of interpulse interactions and can led to stabilization of the periodic arrangement of pulses. The experiment carried out confirms the theoretical predictions and the results of numerical simulation.

We report on a new method for fabrication of saturable absorbers for operation in ring fiber lasers as a mode-locking element taking advantages of the manufacturing technologies of fiber couplers and microfiber tapers coated with carbon nanotubes. It is demonstrated in the experiment that the transmittance of the fabricated saturable absorber increases with an increase of the input radiation power. Also, we have shown that the fabricated saturable absorber enables generation of picosecond soliton pulses in ring fiber laser configuration.

We experimentally demonstrate a harmonically mode-locked Er-doped fiber laser. The distinctive feature of the laser is highly stable pulse trains generated via self-starting hybrid mode-locking triggered by frequency-shifting and nonlinear polarization evolution. A intra-cavity tunable bandpass filter allows getting a pulse repetition rate up to 12 GHz with local adjustment of the wavelength. acceptedVersion

We report on a new, to the best of our knowledge, technique enabling mitigation of the supermode noise (and timing jitter) in a soliton harmonically mode-locked (HML) fiber laser built on the nonlinear polarization evolution (NPE). An optical injection of an external continuous wave (CW) into the HML laser cavity results in an increase of the supermode noise suppression level (SSL) by a two-three order of magnitude for harmonics between 25th and 135th. The operation mechanism involves phase-locking between the injected light and soliton pulses and exhibits strong resonant dependence on the CW laser wavelength. Our findings offer important insights into the HML laser dynamics associated with an interaction between solitons and CW background in the laser cavity.

We report on a new method for fabrication of saturable absorbers for operation in ring fiber lasers as a mode-locking element taking advantages of the manufacturing technologies of fiber couplers and microfiber tapers coated with carbon nanotubes. It is demonstrated in the experiment that the transmittance of the fabricated saturable absorber increases with an increase of the input radiation power. Also, we have shown that the fabricated saturable absorber enables generation of picosecond soliton pulses in ring fiber laser configuration.

In 1992-2001 seventeen patients with juvenile nasopharyngeal angiofibromas (JNAs) were treated at Krasnoyarsk Territorial Clinical Hospital. The patients underwent a comprehensive diagnosis involving computed tomography (CT), magnetic resonance imaging (MRI), and angiography, followed by tumor vascular embolization. Later on JNAs were surgically removed in 14 patients, a course of radiation therapy was performed. In suspected JNA, the authors consider it necessary to concomitantly use CT, MRI, and angiography, which provides the most complete diagnostic picture of a pathological focus. X-ray endovascular occlusion considerably lowers blood loss, facilitates a complete angiofibroma removal, and affects the tolerability of radiation therapy in inoperable cases.

Assessment of hemopheresis effects on calcium-regulating and immune systems, clinical and laboratory activity of rheumatoid arthritis (RA).Hemosorption and plasmapheresis were included in combined treatment of 86 RA patients. Plasmapheresis was performed 3-5 days after hemosorption (a total of 4-6 procedures per course). The activity of RA, immune and calcium-regulating system were assessed clinically, with laboratory tests, enzyme immunoassay.Hemosorption plus plasmapheresis produced positive effects on the disease course, activity. Laboratory indices improved. Percentage of T-helpers and T-suppressors, calcitonin loading rate, levels of parathormone, calcidiol normalized.Combined hemopheresis therapy promotes correction of disorders in immune and calcium-regulating systems.