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The study of multiexcitons in colloidal quantum dots (CQDs) is a timely topic, as these multiexcitons have practical applications in gain devices, photovoltaic cells and as single photon light sources. However, these excitons decay primarily via nonradiative Auger relaxation at a time scale of 10-100 ps, due to the enhancement of many-body interactions inside dots with a typical diameter of 3-4 nm...
The atmospheric profiling of water vapor is necessary for finding life on Mars and weather on Earth. The design and performance of a water vapor lidar based on a Tm:germanate fiber laser is presented.
We demonstrate robustly single-mode power scaling in fiber laser systems built using 35-mum core Yb-doped double-clad chirally-coupled-core (CCC) fibers. Up to 250 W have been demonstrated up to date and further power scaling is in progress.
O-band InAs/InGaAs quantum-dot (QD) laser-diode has been successfully demonstrated by using sandwiched sub-nano separator (SSNS) structures on GaAs. Improvement of crystal-qualities and enhancement of luminescence intensities were attained for the QD laser by SSNS technique.
We demonstrate a novel idea of potentially-compact and cost-effective multiwavelength emitter using a single broadband semiconductor quantum-dash laser device coupled with an arrayed waveguide grating structure, that is suitable for wavelength-division-multiplexing transmission.
We report helicoidal long-period grating by twisting photonic crystal fiber under CO2 laser irradiation and investigated its novel characteristics. The fabricated PCF-LPG endows unique resonance tuning capability with low polarization-dependent loss and thermal shift.
Pulse compression in a differentially pumped gas-filled hollow-fiber was used to generate compressed laser pulses of 1.2 mJ at 3.7 fs, corresponding to 1.5-cycle, 0.3-TW output, from positively chirped 33-fs laser pulses.
Flat and single mode supercontinuum generation spanning from 700 to 2350 nm was demonstrated using a nanosecond microchip laser and conventional cut-off shifted SMF. This configuration is attractive as a simple and low-cost light source.
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 radially polarized beam was amplified up to 1.1 W by passing through an Yb-doped double clad fiber pumped by a semiconductor laser, maintaining both the polarization and intensity patterns of the input beam.
An all-fiber-integrated supercontinuum laser having time-averaged power scalable up to 10.5 W with diffraction limited beam quality is demonstrated. The SC pulses can be generated with arbitrary modulation patterns having on/off durations as short as 10 muS.
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.
Phosphate glasses are excellent host materials for lasers using rare-earth ion transitions. Combining highly-doped phosphate glasses and advanced fiber drawing techniques, we developed phosphate glass fiber lasers and will review recent advances in their performance.
We report a pulsed fiber laser that generates 31-nJ chirped pulses at 70-MHz repetition rate and 2.2 W average power. After dechirping outside the cavity, 80-fs pulses, with 200-kW peak power, are obtained.
Hexagonally stacked all-glass multi-core leakage-channel fibers consisting of seven fused silica cores of up to 100 mum in diameter were fabricated. Simultaneous fundamental mode propagation in all cores and their active coherent combination was demonstrated.
We demonstrate a carrier-envelope-offset-locked frequency comb with 500-pJ pulse energy, with increased coupling efficiency into a tellurite PCF by using angled-V-groove splicing. Carrier-envelope-offset stabilization at telecommunications wavelengths is achieved at the lowest pulse energy.
We demonstrate in situ observation of percussion drilling in stainless steel at axial rates of 40 kHz. The melt cycle is directly observed and imaging feedback is used to improve cut accuracy.
Guided mode resonance filters produced a stable spectrally narrow Thulium fiber laser, at ~1985 nm. Laser spectral linewidths of 10-30 pm with a slope efficiency of ~35% were demonstrated. Spectral reflectivity was explored and showed 0.4-1.0 nm FWHM.
A phase-locked 110-GHz continuously-tunable optical-single-frequency generator is developed based on a phase-stabilized fiber-based comb. Stability of the optical frequencies at 1s are 3.0 and 31times10-12 at scanning speeds of 0.17 and 1 GHz/s, respectively.
A system for multi-kilometer atmospheric propagation experiments including a master oscillator with ~108 nm tunability and a power amplifier tested as an oscillator with ~58% slope efficiency and stable 200 W output power is discussed.
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