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A mode-locking mechanism by active gain modulation is studied numerically and experimentally. The parameter window for the emission of stable pulse trains was found. Pulses as short as 3 ps (~0.5 pJ) were characterized by second-order autocorrelation.
Terahertz is nonlinearly upconverted to telecommunication wavelengths, resulting in detection with 4.5 pW/Hz1/2 noise equivalent power and nanosecond temporal resolution. Optical frequencies from an ultrashort pulse mix, generating 3 mW of broadband terahertz.
We propose spatiotemporal solitons that consist of trains of short pulses. The pulses are collectively trapped in the transversal directions by a slow nonlinearity and each pulse is self-trapped temporally by a fast nonlinearity.
We report GaAs-based transverse-junction-superluminescent-diodes, characterized as transverse-carrier-flow spread in quantum wells horizontally instead of vertical well-by-well injection. These devices overcome the problem of non-uniform-carrier-distribution and operate at a bio-optical window of 1.1-mum wavelength regime.
31% DC to RF differential efficiency of the mode-locked laser's output electrical signal is reported for the first time. The external quantum efficiency of the saturable absorber and the operating regime are also analyzed.
Using a two stage, white-light seeded, collinear, femtosecond optical parametric amplifier based on BIBO crystal, sub-30-fs signal pulses with energies exceeding 200-muJ, corresponding to 5-fold pulse shortening and ~30% internal conversion efficiency, are generated.
New type of non-volatile high-speed optical memory is proposed, which utilize the magnetization reversal of nanomagnet by spin-polarized photo-excited electrons. To verify high speed of proposed demultiplexing method, the switching of spin polarization at 2.2 TGz was demonstrated.
A detailed QD-SESAM growth study enabled the first modelocking of a VECSEL with similar spot size on gain and antiresonant SESAM. Antiresonant designs can strongly improve MIXSELs, a novel type of ultrafast integrated VECSELs.
Microwave and optical frequency references are simultaneously transferred through fiber using a frequency-stabilized mode-locked Er-fiber laser comb. The instability for transferred microwave and optical frequencies are 2.0times10-13 and 7.5times10-15@1 s, respectively, for 3 km transmission.
A stable Sagnac spectral shearing interferometer generating a 0.7-nm shear and interferograms resolvable with a low-resolution spectrometer is demonstrated for real-time optical pulse characterization at microwatt average power.
The distribution of an ultrafast optical pulse train over multiple fiber links with long-term stable timing precision within 2 femtoseconds rms is accomplished by integrating a polarization maintaining output with 300 meter long fiber links.
The combination of collinear time-resolved two-dimensional spectroscopy and field-resolved detection allows for the measurement of optical nonlinearities of arbitrary order. Results are presented for intersubband transitions in a multiple quantum well sample.
Phase to frequency conversion is demonstrated with a synchronously modelocked optical parametric oscillator, with a sensitivity of 16 MHz/radian, and a phase resolution of 9ldr10-8 radian.
We report the observation of up to 5 Rabi cycles in a single molecule. A pi-pulse excitation is achieved with 500 photons, marking an important step towards preparation of coherent superposition states with few photons.
We use a heterodyne NSOM with superluminescent diode illumination to measure the loss in an SOI waveguide around a bend. For a bend of radius 10 mum, we measure loss of 0.09 dB.
Femtosecond switching of anisotropic nanostructure indicating birefringence with a time constant of plusmnb200 fs was observed. Such anisotropy has evolved by lowering threshold for defect formation and enhanced coherency of the electron plasma wave.
We demonstrate that the sign of detuning of an optical pulse train from quantum dot resonances controls the direction of nuclear spin flips. This effect can produce a narrow, precise distribution of nuclear spin polarizations.
Trapped between high numerical aperture laser objectives, a single calcium ion is converted into a high-efficiency source of single photons, with controlled coherence properties. Thereby, various schemes to establish entanglement between remote ions are probed.
We report pronounced light-induced change of the optical activity at terahertz frequency in metal chiral gratings on semiconductor substrates. This result opens new horizons in the active terahertz polarization control.
We propose and demonstrate a concept for temporal integration of optical waveforms with no fundamental limitation on the device's operation time window and frequency bandwidth using a pulse multiplier concatenated with a fiber Bragg grating.
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