Sub-picosecond green-pumped OPG/OPA using non-critical phase matching in LBO was investigated at high average powers, utilizing a novel high-power ultrafast fiber laser providing 300W of 1ps pulses at 515nm and 1.4GHz pulse repetition rate. The 4-stage collinear OPA produced about 100W of combined Signal plus Idler output powers when tuning the Signal wavelength between 740nm and 940nm. An extended spectral tuning range between 300nm and 1800nm with average power between 10W and 70W was demonstrated by using SFG of Signal plus Pump and SHG of Signal and of Idler. The OPA output pulse durations were ~0.5ps long.
Scanner Focus window of the lithographic process becomes much smaller due to the shrink of the device node and multipatterning approach. Consequently, the required performance of scanner focus becomes tighter and more complicated. Focus control/monitoring methods such as “field-by-field focus control” or “intra-field focus control” is a necessity. Moreover, tight scanner focus performance requirement starts to raise another fundamental question: accuracy of the reported scanner focus.
The insufficient accuracy of the reported scanner focus using the existing methods originates from:
a) Focus measurement quality, which is due to low sensitivity of measured targets, especially around the nominal production focus.
b) The scanner focus is estimated using special targets, e.g. large pitch target and not using the device-like structures (irremovable aberration impact).
Both of these factors are eliminated using KLA-Tencor proprietary “Focus Offset” technology.
We experimentally demonstrate optical clock recovery from quantum dot mode-locked semiconductor lasers by
interband optical pulse injection locking. The passively mode-locked slave laser oscillating on the ground state is locked
through the injection of optical pulses generated via the first excited state transition from the hybridly mode-locked
master laser. When an optical pulse train generated via the first excited state from the master laser is injected to the slave
laser oscillating via ground state, the slave laser shows an asymmetric locking bandwidth around the nominal repetition
rate of the slave laser.
We study the characteristics of wavelength tunable quantum-dot mode-locked lasers using a curved two-section device, external grating, and optical bandpass filter. Wide wavelength tunability is demonstrated due to the fact that the center wavelength of mode-locking is extended to excited state transitions as well as ground state transitions of the quantum-dot gain media.
Quantum-dot lasers have shown remarkable properties, such as temperature-insensitive operation, low loss, efficient
carrier recombination, ultrafast gain recovery time, suppression of beam filamentation, reduced sensitivity to optical
feedback, etc. These excellent performances will contribute to open new cost effective and improved lightwave
communication systems. We exploit the performance of mode-locking of quantum-dot lasers for ultrashort, high power,
and low noise optical pulse generation using two-section mode-locked laser diodes and a semiconductor optical
amplifier (SOA)-based ring laser cavity.
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