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ABSTRACT: We demonstrate ultrahigh-resolution optical coherence tomography (OCT) using continuum generation in an air-silica microstructure fiber as a low-coherence light source. A broadband OCT system was developed and imaging was performed with a bandwidth of 370 nm at a 1.3-mu;m center wavelength. Longitudinal resolutions of 2.5 microm in air and ~2 microm in tissue were achieved. Ultrahigh-resolution imaging in biological tissue in vivo was demonstrated.
Optics Letters 06/2001; 26(9):608-10. · 3.40 Impact Factor
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ABSTRACT: By spanning an optical octave (>300 THz) with a broadened
femtosecond laser frequency comb, we directly measure the frequencies of
optical standards at 1064/532 nm, 633 nm and 778 nm in terms of the
microwave frequency that controls the comb spacing. This microwave
frequency can be linked directly to the cesium standard
IEEE Transactions on Instrumentation and Measurement 05/2001; · 1.21 Impact Factor
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ABSTRACT: The frequency of the Calcium ^3P_1--^1S_0 intercombination line at 657 nm is phase-coherently measured in terms of the output of a primary cesium frequency standard using an optical frequency comb generator comprising a sub-10 fs Kerr-lens mode-locked Ti:Sapphire laser and an external microstructure fiber for self-phase-modulation. The measured frequency of \nu_Ca = 455 986 240 494 276 Hz agrees within its relative uncertainty of 4 10^-13 with the values previously measured with a conceptually different harmonic frequency chain and with the value recommended for the realization of the SI unit of length. Comment: 4 pages, 2 ps-figures
10/2000;
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ABSTRACT: We analyze the waveguide properties of microstructure optical fibers consisting of a silica core surrounded by a single ring of large air holes. Although the fibers can support numerous transverse spatial modes, coupling between these modes even in the presence of large perturbations is prevented for small core dimensions, owing to a large wave-vector mismatch between the lowest-order modes. The result is an optical fiber that can appear single mode with propagation properties that can be achieved only in multimode waveguides.
Optics Letters 07/2000; 25(11):796-8. · 3.40 Impact Factor
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ABSTRACT: We stabilized the carrier-envelope phase of the pulses emitted by a femtosecond
mode-locked laser by using the powerful tools of frequency-domain
laser stabilization. We conÞrmed control of the pulse-to-pulse carrier-envelope
phase using temporal cross correlation. This phase stabilization locks the absolute
frequencies emitted by the laser, which we used to perform absolute
optical frequency measurements that were directly referenced to a stable
microwave clock.
Science 04/2000; 288(1095-9203):635. · 31.20 Impact Factor
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ABSTRACT: We stabilized the carrier-envelope phase of the pulses emitted by a femtosecond mode-locked laser by using the powerful tools of frequency-domain laser stabilization. We conÞrmed control of the pulse to-pulse carrier-envelope phase using temporal cross correlation. This phase stabilization locks the absolute frequencies emitted by the laser, which we used to perform absolute optical frequency measurements that were directly referenced to a stable microwave clock.
Science. 04/2000; 288:635.
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ABSTRACT: Microstructure air-silica optical fibers with anomalous
group-velocity dispersion at visible wavelengths are demonstrated. The
linear and nonlinear optical properties of these structures are examined
and their potential applications discussed
Optical Fiber Communication Conference, 2000; 02/2000
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ABSTRACT: We demonstrate experimentally for what is to our knowledge the first time that air-silica microstructure optical fibers can exhibit anomalous dispersion at visible wavelengths. We exploit this feature to generate an optical continuum 550 THz in width, extending from the violet to the infrared, by propagating pulses of 100-fs duration and kilowatt peak powers through a microstructure fiber near the zero-dispersion wavelength.
Optics Letters 02/2000; 25(1):25-7. · 3.40 Impact Factor
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ABSTRACT: We have shown by measuring the beat frequency between the
supercontinuum (SC) and the optical parametric oscillator (OPO) 2ω
<sub>s</sub> subharmonic, we can observe and control the relative phase
slip between the pump and signal. The relative phase slip can be
controlled for a large OPO signal range since the 2ω<sub>s</sub>
subharmonic is mixed with the SC. It is possible to use the SC to extend
carrier-envelope locking so that both the Ti:sapphire pulse and OPO
signal are locked to an absolute reference
Lasers and Electro-Optics Society 2000 Annual Meeting. LEOS 2000. 13th Annual Meeting. IEEE; 02/2000
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ABSTRACT: We demonstrate for the first time the efficient generation of a
single-transverse-mode continuum with a spectral width of 500 THz, by
propagating pulses for 100-fs duration and kilowatt peak powers through
an air-silica microstructure optical fiber designed to have anomalous
dispersion at 800 nm
Lasers and Electro-Optics, 1999. CLEO '99. Summaries of Papers Presented at the Conference on; 06/1999
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ABSTRACT: Summary form only given. The authors theoretical and experimental
results demonstrate that the nonlinear Schrodinger equation (NLSE),
which includes the effects of self-steepening and space-time focusing,
gives an accurate description of the pulse-splitting dynamics in the
self focusing of femtosecond laser pulses
Quantum Electronics Conference, 1998. IQEC 98. Technical Digest. Summaries of papers presented at the International; 06/1998
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ABSTRACT: We utilize the two-photon conductivity of a fused-silica substrate to produce a photoconductive switch for use in an intensity autocorrelator for ultraviolet ultrashort pulses. We perform measurements at 267 nm with pulse durations in the range of 110-330 fs and with energies as weak as 10 nJ. Based on the bandgap of fused silica, this device can potentially operate in the wavelength range of 140-280 nm.
Optics Letters 06/1998; 23(10):798-800. · 3.40 Impact Factor
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ABSTRACT: We show theoretically and experimentally that with ultrashort pulses much longer than a single optical cycle, the effects of self-steepening and space-time focusing are important for describing the nonlinear dynamics of self-focusing. Asymmetric temporal splitting of the pulse envelope is observed in which the relative magnitudes of the peaks are reversed as the input power is increased.
Optics Letters 05/1998; 23(7):534-6. · 3.40 Impact Factor
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ABSTRACT: We experimentally characterize the two-photon response of a GaAsP photodiode by use of a femtosecond Ti:sapphire laser tuned below the diode bandgap. The photodiode is shown to be highly suitable for real-time second-order autocorrelation measurements of pulses as short as 6fs in duration and with energies as small as a few picojoules.
Optics Letters 10/1997; 22(17):1344-6. · 3.40 Impact Factor
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ABSTRACT: We extend the z-scan technique to provide for measurements of the sign and the magnitude of all the independent components of chi((3)) for isotropic and cubic-symmetry materials. This technique is used to measure the dispersion of the tensor components of the real and the imaginary parts of chi((3)) for various wide-gap semiconductor materials by use of femtosecond laser pulses. Our measurements of the polarization dichroism of the nonlinear-index and two-photon absorption coefficients are in fair agreement with recent theoretical calculations; however, substantial discrepancies exist between the measured and predicted values for the corresponding anisotropy parameters.
Optics Letters 05/1995; 20(10):1110-2. · 3.40 Impact Factor
