[Show abstract][Hide abstract] ABSTRACT: In this paper, we demonstrate, for the first time to the best of our knowledge, utilization of Bessel beams generated from a semiconductor laser for optical trapping and manipulation of microscopic particles including living cells.
[Show abstract][Hide abstract] ABSTRACT: We report picosecond operation of a diode-pumped, Er,Yb-waveguide laser near 1550 nm, passively mode-locked using a quantum dot SESAM. A fundamental repetition rate of 6.8 GHz and an output power of 30 mW are achieved.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate passively mode-locked Yb<sup>3+</sup>-doped glass waveguide lasers in a quasi-monolithic configuration with a maximum pulse repetition frequency up to 15.2 GHz. A semiconductor saturable absorber mirror (SESAM) is used to achieve stable mode-locking around 1050 nm with pulse durations as short as 811 fs and an average power up to 27 mW. Different waveguide samples are also employed to deliver pulses with repetition rates of 4.9 GHz, 10.4 GHz and 12 GHz with an average power of 32 mW, 60 mW and 45 mW, respectively. The group velocity dispersion control in the cavity is provided by changing the gap between the SESAM and the waveguide end-face to facilitate a soliton mode-locking regime.
[Show abstract][Hide abstract] ABSTRACT: In this work we study the effect of slow passage in the pulse-pumped dual-state-lasing quantum dot laser. During
pulsed operation close to the excited-state threshold, the output pulse shape becomes unstable. After the rise stage, the
output power sharply drops out. It is followed by instabilities that may appear after a significant delay.
21st Int. Symp. “Nanostructures: Physics and Technology”, St Petersburg Academic University, Saint Petersburg, Russia.; 06/2013
[Show abstract][Hide abstract] ABSTRACT: Calcium phosphate (CaP) minerals were synthesized with photo‐active erbium oxide (Er2O3), and acid‐resistant phase mixture of aluminum phosphate (AlPO4) and calcium fluoride (CaF2) at room temperature via precipitation from the aqueous solution of hydrated calcium nitrate Ca(NO3)2·4H2O and ammonium hydrogen phosphate (NH4)2HPO4. The dominant precipitated phases, characterized by X‐ray powder diffraction, confirmed the presence of monetite (CaHPO4) and brushite (CaHPO4·2H2O) at room temperature. The microstructural analysis showed the presence of platelet‐like features of monetite and brushite, which were tested for occlusion of dentinal tubules via irradiation with a 100 fs pulse duration laser, operating at 1520 nm at 2.5 GHz repetition rate. The SEM analysis of dentinal tubule over the occluded surface showed a continuum of 10 µm layer, which covered several 100s of micrometer surface. The results open the opportunity for dentinal tubule occlusion via ultrafast laser sintering using acid‐resistant minerals.
Journal of the American Ceramic Society 09/2012; 95(9). · 2.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Femtosecond mode locking of a Tm-doped Lu<sub>2</sub>O<sub>3</sub> ceramic laser is reported. Transform-limited pulses as short as 180 fs are generated at 2076 nm with an average output power of 400 mW and a pulse repetition frequency of 121.2 MHz. An output power up to 750 mW can be reached at the somewhat longer pulse duration of 382 fs. Femtosecond pulse generation is realized in the 2030-2100 nm spectral range. Passive mode locking was achieved using an ion-implanted InGaAsSb quantum-well-based SESAM.
[Show abstract][Hide abstract] ABSTRACT: Femtosecond mode locking of a Tm-doped Lu2O3 ceramic laser is reported. Transform-limited pulses as short as 180 fs are generated at 2076 nm with an average output power of 400 mW and a pulse repetition frequency of 121.2 MHz. An output power up to 750 mW can be reached at the somewhat longer pulse duration of 382 fs. Femtosecond pulse generation is realized in the 2030-2100 nm spectral range. Passive mode locking was achieved using an ion-implanted InGaAsSb quantum-well-based SESAM.
[Show abstract][Hide abstract] ABSTRACT: A fiber Raman probe based sensor is designed to be integrated into a surgical robot. The chemical information obtained from this sensor would assist tissue margin detection and surgical guidance during laparoscopic surgical procedures.
Digital Holography and Three-Dimensional Imaging; 04/2012
[Show abstract][Hide abstract] ABSTRACT: We demonstrate the passive mode-locking operation of an in-band-pumped Ho:YLiF(4) laser at 2.06 μm using a semiconductor saturable absorber mirror based on InGaAsSb quantum wells. A transform-limited pulse train with minimum duration of 1.1 ps and average power of 0.58 W has been obtained at a repetition frequency of 122 MHz. A maximum output power of 1.7 W has been generated with a corresponding pulse duration of 1.9 ps.
[Show abstract][Hide abstract] ABSTRACT: Femtosecond modelocking in Tm,Ho-codoped NaY(WO4)2 and KY(WO4)2 lasers is reported. Transform-limited 191-fs pulses are produced at 2060 nm at a repetition frequency of 144 MHz. Output power exceeds 200 mW during femtosecond pulse generation.
[Show abstract][Hide abstract] ABSTRACT: Passive mode locking of a Tm3+,Ho3+:KY(WO4)2 laser with an InGaAsSb-based saturable absorber is reported. Transform-limited 570-fs pulses were generated at 2055nm with an average power of 130mW at a pulse repetition frequency of 118MHz.
[Show abstract][Hide abstract] ABSTRACT: We report on fast switching between continuous-wave mode-locked and continuous-wave operation of a Cr4+:forsterite femtosecond laser operating at 1300 nm, by means of a GaInNAs SESAM that is optically excited by an external diode laser.
International Conference on Ultrafast Phenomena; 01/2010
[Show abstract][Hide abstract] ABSTRACT: Stable mode locking is demonstrated in a Cr4+:forsterite laser incorporating quantum-dot SESAMs operating either through ground-state or excited-state transitions to initiate and maintain the generation of pulses as short as 100fs and 122fs respectively.
[Show abstract][Hide abstract] ABSTRACT: We report the first use of a Semiconductor Disk Laser (SDL) as a pump source for ~2mum-emitting Tm3+ (,Ho3+)-doped dielectric lasers. The ~1213nm GaInNAs/GaAs SDL produces >1W of CW output power, a maximum power transfer net slope efficiency of 18.5%, and a full width half maximum wavelength tuning range of ~24nm. Free-running operation of a Tm3+-doped tellurite glass laser under 1213nm SDL pumping generated up to 60mW output power with 22.4% slope efficiency. Wavelength tunable output is also obtained from 1845 to 2043nm. Improved performance with output powers of ~200mW and a slope efficiency of ~35% are achieved by replacing the Tm3+-doped glass with a Tm3+-doped KYW active medium. Emission of a Tm3+,Ho3+-codoped tellurite glass laser is also reported with maximum output power of ~12mW and a ~7% slope efficiency. Finally, preliminary investigations of 1213nm-pumping of a Tm3+,Ho3+-codoped silica fibre laser lead to 36mW output power with ~19.3% slope efficiency.
Proceedings of SPIE - The International Society for Optical Engineering 02/2009; · 0.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The growth, spectroscopy and lasing performance of a Tm,Ho:KY(WO4)2crystal are reported. An average power up to 390mW is generated at 2058nm with a corresponding slope efficiency of 42% during continuous-wave operation at room temperature.
[Show abstract][Hide abstract] ABSTRACT: We report on precise two-photon ablation with 110 fs laser pulses at 1278 nm, emitted from a Cr:forsterite laser. Selective two-photon ablation of Muntjac deer chromosomes is demonstrated. The two-photon absorption at 639 nm was enhanced by using Methylene blue dye as a photosensitizer. This stain has a strong absorption in the region around 650 nm but 100% transmission around 1300 nm, allowing increased specificity: material that has absorbed the dye is ablated but undyed material is left unaffected. The low group velocity dispersion in glass at 1278 nm led to negligible pulse broadening in the focusing objective where the 100 fs pulses stretched to 110 fs. This contrasts to the 100 fs pulses at 780 nm that were measured to stretch to 300 fs under the same conditions.
Journal of Optics A Pure and Applied Optics 05/2007; 9(6):S19. · 1.92 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We report the first demonstration of a passively mode-locked femtosecond Cr4+:YAG laser incorporating a GaInNAs saturable Bragg reflector to mode lock around 1500nm. 132fs pulses were generated with an output power of 140mW.
[Show abstract][Hide abstract] ABSTRACT: A passive, optical cell sorter is created using the light pattern of a 'nondiffracting' beam-the Bessel beam. As a precursor to cell sorting studies, microspheres are used to test the resolution of the sorter on the basis of particle size and refractive index. Variations in size and, more noticeably, refractive index, lead to a marked difference in the migration time of spheres in the Bessel beam. Intrinsic differences (size, refractive index) between native (unlabeled) cell populations are utilized for cell sorting. The large difference in size between erythrocytes and lymphocytes results in their successful separation in this beam pattern. The intrinsic differences in size and refractive index of other cells in the study (HL60 human promyelocytic leukaemic cells, murine bone marrow, and murine stem/progenitor cells) are not large enough to induce passive optical separation. Silica microsphere tags are attached to cells of interest to modify their size and refractive index, resulting in the separation of labeled cells. Cells collected after separation are viable, as evidenced by trypan blue dye exclusion, their ability to clone in vitro, continued growth in culture, and lack of expression of Caspase 3, a marker of apoptosis.
Journal of Biomedical Optics 01/2007; 12(5):054017. · 2.75 Impact Factor