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Mid-infrared beam shaping is demonstrated by using grating coupled surface emitting quantum cascade ring lasers. The devices allow for far-field tuning, ranging from highly symmetric spot-to ring-shaped beam patterns, depending on the grating period.
We have succsessfully developed blue-violet laser diodes having the world's highest output power of 450 mW by introducing a novel facet coating structure, reducing the internal loss in devices, and making a cavity length long.
An Yb-doped fiber laser and amplifier system is used together with an enhancement cavity for high harmonic generation for precision spectroscopy. Higher order harmonics can be produced in comparison to systems with Ti:sapphire lasers.
Spin-polarized lasers offer new encouraging possibilities for future devices. We compare time-resolved luminescence measurements with theoretical models for spin dynamics in spin-polarized lasers and demonstrate ultrafast polarization switching during one short single-mode laser pulse.
We developed a three terminal mid-infrared quantum cascade laser. The third terminal allows one to electrically modulate the optical losses and thus the laser output-independently of the laser's driving current.
Narrowband output at 1.5 THz was produced in periodically-inverted GaAs placed inside a high-finesse ring-cavity fiber-laser-pumped degenerate PPLN OPO containing a thin Fabri-Perot etalon. Over 10-microWatt average power was generated using 2 W of laser pump.
We demonstrate single-mode, surface-emitting terahertz lasers at lambdaap110 mum employing photonic-crystal resonators. The devices employ metal-metal waveguides, and the photonic-crystal lattice is implemented by the sole patterning of the top metal contact, without deep-etching the semiconductor in the photonic crystal holes. The device emission wavelength correctly tunes with the photonic crystal...
A fundamentally mode-locked Er:Yb:glass laser with a record high repetition rate of 101 GHz generates 30 mW average power in 1.1-ps pulses in the 1.5-mum telecom window. Frequency degeneracies of transverse cavity-modes are investigated.
We demonstrate error free transmission at bit rates up to 32 Gb/s at room temperature and 25 Gb/s at 85degC using a 9 mum oxide aperture 850 nm VCSEL. The VCSEL design is optimized for high speed operation by minimizing parasitics, reducing self-heating, and using strained InGaAs quantum wells to improve differential gain.
We show the effects of shrinking the high contrast grating size on a wavelength-tunable VCSEL experimentally and theoretically. With a grating having only 4 periods, we demonstrate the fastest tunable VCSEL with speed >25 MHz.
Recent progress on fabrication technology and demonstration of current injection GaN-based blue VCSELs are presented. Performance of current injection blue VCSELs with threshold current of 1.4 mA and emission wavelength of 462 nm are described.
Broadband thermal infrared heterodyne spectro-radiometry performed over a frequency range of more than 100 cm-1 at lambda=8.4 mum using an external cavity quantum cascade laser as a tunable local oscillator will be reported.
We demonstrate full control of the spectral and spatial emission properties of terahertz quantum cascade lasers using metallic photonic-crystals for lateral confinement. Single-mode, surface-emission is obtained at a frequency of 2.8-2.9 THz using a photonic-crystal design with a square lattice geometry. The resonator quality factor is then optimised, using a graded photonic-crystal architecture,...
Single higher-order transverse mode operation with radial polarization of a Nd:YAG laser was demonstrated by use of a spatially reflectivity-modulated output coupler. By adjusting the cavity, TM02, TM03, and TM04 modes were selectively obtained.
We have implemented a new means of measuring very high frequency ultrasound in nanostructured materials (known as Picosecond Ultrasonics) by using a high-Q optical resonator that enables significant enhancement and detailed characterization of ultrasound signals.
By varying the length of a flat-flat cavity, polarization selective operation of a Nd:YAG laser was achieved only in a stable region of either TM01 or TE01 mode based on cavity stability incorporating thermally effects.
We demonstrated over 100-nm RGB tunable laser operation (479-497, 515-546, 597-650 nm) using a single 9-cm Pr3+-doped ZBLAN fiber pumped by a GaN-LD. The optimized laser cavity at 635 nm realized slope efficiency of 0.69.
Through a fused silica light guide assembly, the concentrated solar radiation is efficiently focused into a small diameter Nd:YAG rod by a sharp elliptical cavity. TEM00 laser power is triple that of the 2D-DCPC cavity.
Varying quantum cascade laser cavity length results in gain peak selection across a 118 cm-1 range; a result of a change in threshold voltage, and applied electric field as a function of cavity length.
We experimentally demonstrate error-free 10 Gb/s transmission over the largest core size fiber ever reported. A transverse tolerance of plusmn30 mum is demonstrated for both the VCSEL source and PIN diode receiver.
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