Mode control in wafer-fused 1.3 mu m wavelength coupled-VCSEL arrays is achieved by cavity structuring and investigated by spectrally resolved near- and far-field measurements. Improved mode discrimination is attained by combining index- and gain-patterning. (C)2010 Optical Society of America
Significant THz power enhancement and polarity reversal were observed from Mg-doped InN. The carrier concentration-dependent THz polarity reversal reflects the interplay between the surface-electric-field and the photo-Dember field for THz emission from InN:Mg.
We demonstrate a stable 10GHz harmonically modelocked laser employing a 151cm-long bismuth-based highly nonlinear erbium-doped fiber and a bandwidth-variable tunable filter. The wavelength tuning range is 80nm. The pulsewidth is varied from 7.8ps to 23.1ps.
A frequency comb is phase-locked to a cw laser with an electro-optic-modulator providing 1.6 MHz feedback bandwidth. Residual phase noise is as low as −94 dBc/Hz, and the comb remained locked under mechanical vibration of up to 1.9 g.
We measure the nonlinearity and transparency of mixed GaS x Se 1−x crystals and show that GaS 0.4 Se 0.6 is a promising nonlinear material for mid-IR (≫5 µm) OPO operation without twophoton absorption for a pump wavelength of 1064 nm.
We report visible (green) third-harmonic generation in silicon by launching near-infrared picosecond pulses into highly confined photonic crystal waveguides. We demonstrate slow light enhancement of this nonlinear process.
We introduce a method for calculating Pockels coefficients in SiGe superlattices. We show that the Pockels effect in (Si)1(Ge)1 superlattices is half as strong as in GaAs. This opens a path to efficient CMOS-compatible modulators.
We present an experimental study of a simple low-threshold Raman fiber laser, pumped by amplified spontaneous emission (ASE) of an erbium doped fiber amplifier. Such pumping for stimulated Raman scattering (SRS) and Raman laser, that is used to the best our best knowledge for the first time, suppresses stimulated Brillouin scattering and thus increases the pumping efficiency. The ASE pump had a central wavelength at 1550 nm and the outcome RFL oscillation wavelength was around 1670 nm, determined by the fiber Bragg gratings that formed the fiber resonator. We used various types of fibers, cavity lengths (2 - 25 km) and output grating reflectivities (4 - 97%). We obtained 34% overall laser to pump power efficiency and a pumping threshold power as low as ~160mW (as far as we know, the lowest ever achieved so far).
We present a technique for measuring absolute range that uses two mismatched frequency combs to measure distance over 1.5 m range with 10 nm level statistical uncertainty.
We compare wavepackets induced by “R-dependent ionization” and bond-softening in strong fields through both simulations and experiments. We conclude that the former produces stronger vibrations in hot molecules than the latter and results in vibrational cooling.
A new regime of pulse parameters in a normal-dispersion fiber laser is identified. Dissipative solitons exist with remarkably large pulse duration and chirp, along with large pulse energy. A low-repetition-rate oscillator that generates pulses with large and linear chirp can replace the standard oscillator, stretcher, pulse-picker, and preamplifier in a chirped-pulse fiber amplifier. The theoretical properties of such a giant-chirp oscillator are presented. A fiber laser designed to operate in the new regime generates approximately 150 ps pulses at a 3 MHz repetition rate. Amplification of these pulses to 1 microJ energy with pulse duration as short as 670 fs demonstrates the promise of this new approach.
This paper demonstrates single-shot, four-quadrature balanced homodyne detection in the spectral domain for full field measurements of 500-GHz bandwidth 150-aJ optical waveforms with 200-ps record lengths. Results indicate essentially quantum-limited performance.
A cladding-modulated Bragg grating implemented using periodic placements of silicon cylinders in the cladding along a silicon waveguide is proposed. Modeling results are verified experimentally, demonstrating coupling strengths differing by an order of magnitude.
A time-gated filter is demonstrated that converts a double-sideband radio-frequency waveform on a pulsed optically chirped carrier into a single sideband waveform. The filter is used to reduce the dispersion penalty in time-stretch ADCs.
A cooled, trapped Mg+ ion is excited using a continuous, blue-detuned pump. Coherent oscillatory motion is observed. It is shown to result from stimulated emission of center-of-mass phonons, constituting the mechanical analog of a laser.
We present an experiment where the motion of a silicon micro-mechanical resonator is optically monitored in a high-finesse cavity with a quantum-limited sensitivity. Directs effects of intracavity radiation pressure are experimentally demonstrated. Further experimental progress and cryogenic operation may allow for quantum optics experiments and lead to the experimental observation of the quantum ground state of a mechanical resonator.
