Optics Letters

Larger-area single-mode photonic crystal surface-emitting lasers enabled by an accidental Dirac point

Song-Liang Chua, Ling Lu, Jorge Bravo-Abad, John D. Joannopoulos, Marin Soljačić
By altering the lattice geometry of the photonic crystal (PhC) surface-emitting lasers (PCSELs), we tune the regular lasing band edges of quadratic dispersions to form a single accidental Dirac point of linear dispersion at the Brillouin zone center. This not only increases the mode spacing by ... [Opt. Lett. 39, 2072-2075 (2014)]

Digitally enhanced optical fiber frequency reference

Terry G. McRae, Silvie Ngo, Daniel A. Shaddock, Magnus T. L. Hsu, Malcolm B. Gray
We use digitally enhanced heterodyne interferometry to measure the stability of optical fiber laser frequency references. Suppression of laser frequency noise by over four orders of magnitude is achieved using post processing time delay interferometry, allowing us to measure the mechanical ... [Opt. Lett. 39, 1752-1755 (2014)]

Photonic crystal fiber half-taper probe based refractometer

Pengfei Wang, Ming Ding, Lin Bo, Chunying Guan, Yuliya Semenova, Weimin Sun, Libo Yuan, Gilberto Brambilla, Gerald Farrell
A compact single-mode photonic crystal fiber single-mode fiber tip (SPST) refractive index sensor is demonstrated in this Letter. A CO_2 laser cleaving technique is utilized to provide a clean-cut fiber tip, which is then coated by a layer of gold to increase reflection. An average sensitivity of ... [Opt. Lett. 39, 2076-2079 (2014)]

Watt-level short-length holmium-doped ZBLAN fiber lasers at 1.2  μm

Xiushan Zhu, Jie Zong, Kort Wiersma, R. A. Norwood, Narasimha S. Prasad, Michael D. Obland, Arturo Chavez-Pirson, N. Peyghambarian
In-band core-pumped Ho^3+-doped ZBLAN fiber lasers at the 1.2 μm region were investigated with different gain fiber lengths. A 2.4 W 1190 nm all-fiber laser with a slope efficiency of 42% was achieved by using a 10 cm long gain fiber pumped at a maximum available ... [Opt. Lett. 39, 1533-1536 (2014)]

Influence of nodular defects on the laser damage resistance of optical coatings in the femtosecond regime

Laurent Gallais, Xinbin Cheng, Zhanshan Wang
The influence of nodular coating defects on the sub-picosecond laser damage resistance of multilayer coatings is investigated. The study is conducted on engineered nodules from monodisperse silica microspheres in HfO_2/SiO_2 high-reflective mirrors, at 400  fs/1030  nm. ... [Opt. Lett. 39, 1545-1548 (2014)]

41.9  fs hybridly mode-locked Er-doped fiber laser at 212  MHz repetition rate

Xing Li, Weiwen Zou, Jianping Chen
We demonstrate a hybridly mode-locked erbium-doped fiber laser. It combines saturable absorption and nonlinear polarization evolution to produce stable and purified femtosecond pulses with a high repetition rate of 212 MHz. The average output power is larger than 65 mW, and the ... [Opt. Lett. 39, 1553-1556 (2014)]

Simultaneous picosecond and femtosecond solitons delivered from a nanotube-mode-locked all-fiber laser

D. D. Han, X. M. Liu, Y. D. Cui, G. X. Wang, C. Zeng, L. Yun
We propose a compact nanotube-mode-locked all-fiber laser that can simultaneously generate picosecond and femtosecond solitons at different wavelengths. The pulse durations of picosecond and femtosecond solitons are measured to be ∼10.6  ps and ∼466  fs, ... [Opt. Lett. 39, 1565-1568 (2014)]

High-energy diode-seeded nanosecond 2  μm fiber MOPA systems incorporating active pulse shaping

Z. Li, A. M. Heidt, P. S. Teh, M. Berendt, J. K. Sahu, R. Phelan, B. Kelly, S. U. Alam, D. J. Richardson
We report on high-energy nanosecond-pulsed fiber master oscillator power amplifier (MOPA) systems seeded by semiconductor laser diodes at 2 μm incorporating arbitrary pulse-shaping capabilities. Two MOPA systems, one based on direct diode modulation and the second using additional ... [Opt. Lett. 39, 1569-1572 (2014)]

Optical noise of stabilized high-power single frequency optically pumped semiconductor laser

Alexandre Laurain, Cody Mart, Jörg Hader, Jerome V. Moloney, Bernadette Kunert, Wolfgang Stolz
We present a study of an actively stabilized optically pumped semiconductor laser operating single frequency at a wavelength of 1015 nm. In free running operation, the laser exhibits a single frequency output power of 15 W with a linewidth of 995 kHz for a sampling time of 1 s. ... [Opt. Lett. 39, 1573-1576 (2014)]

Tracking shear waves in turbid medium by light: theory, simulation, and experiment

Sinan Li, Yi Cheng, Lipei Song, Robert J. Eckersley, Daniel S. Elson, Meng-Xing Tang
Shear wave propagation provides rich information for material mechanical characterization, including elasticity and viscosity. This Letter reports tracking of shear wave propagation in turbid media by laser-speckle-contrast analysis. The theory is described, and a Monte Carlo simulation of light ... [Opt. Lett. 39, 1597-1600 (2014)]

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