[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.
[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.
No preview · Article · Sep 2012 · Journal of the American Ceramic Society
[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. (C) 2012 Optical Society of America
[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.
[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.
[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.
Full-text · Article · Feb 2009 · Proceedings of SPIE - The International Society for Optical Engineering
[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: Efficient passive mode locking in a diode-pumped Er,Yb:YAl3(BO3)4 laser has been demonstrated using low-loss GaInNAs-based SESAMs. 3.2-ps and 5.1-ps pulses were produced at 1530nm and 1550nm, respectively, with corresponding average powers of 280mW and 103mW.
[Show abstract][Hide abstract] ABSTRACT: In human breast tumors, a 1-2 degrees C increase in skin surface temperature is usually observed at the periphery; it has been proposed that this change is due to the hypervascularity and increased blood flow resulting from tumor-associated angiogenesis. Here we tested the hypothesis that thermal imaging might represent a useful adjunctive technique in monitoring the growth dynamics of human tumor xenografts. Xenografts were established in immunocomprised nude mice using MDA-MB-231 or MCF7 breast cancer cells. We exploited the inherent noncontact and noninvasive advantages of infrared thermography to detect skin surface temperature changes. Continuous thermographic investigation was performed to detect and monitor tumor growth in vivo and high resolution digital images were analyzed to measure the tumor temperature dynamics. In contrast to the skin temperature increases associated with human breast cancer, a consistent temperature decrease was found in the xenograft mice. In one case, a smaller secondary tumor, otherwise undetectable, was clearly evident by thermal imaging. The tumors were cooler than the surrounding tissue with a maximum temperature reduction of 1.5 degrees C for MDA-MB-231 tumor and 3 degrees C for MCF7 tumors observed on day 14. In addition, the temperature of the xenograft tumors decreased progressively as they grew throughout the observation period. It was demonstrated that thermographic imaging could detect temperature changes as small as 0.1 degrees C on the skin surface at an early stage of tumor development. The findings of the study indicate that thermographic imaging might have considerable potential in monitoring human tumor xenografts and their response to anticancer drugs.
Full-text · Article · Sep 2007 · International Journal of Cancer
[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.
No preview · Article · Sep 2007 · Journal of Biomedical Optics