Mask topography effects need to be taken into consideration for more advanced resolution enhancement techniques in optical lithography. However, rigorous 3D mask model achieves high accuracy at a large computational cost. This work develops a combined source, mask and pupil optimization (SMPO) approach by taking advantage of the fact that pupil phase manipulation is capable of partially compensating for mask topography effects. We first design the pupil wavefront function by incorporating primary and secondary spherical aberration through the coefficients of the Zernike polynomials, and achieve optimal source-mask pair under the condition of aberrated pupil. Evaluations against conventional source mask optimization (SMO) without incorporating pupil aberrations show that SMPO provides improved performance in terms of pattern fidelity and process window sizes.
We describe the design and characterization of a silicon nanophotonic waveguide (SNW) and its use in a reconfigurable
microwave photonic filter (MPF). The SNW is dispersion tailored for efficient on-chip four-wave-mixing. We use the onchip
four-wave-mixing to increase the number of taps in our multiple tap delay line MPF. The tap levels are controlled by
a programmable filter. Using a 12 mm long SNW reduces the footprint by five orders of magnitude compared to silica
highly nonlinear fiber while only requiring approximately two times more input power.
We propose and demonstrate a novel approach to implement a multi-tap photonic microwave filter. By using a twopump
fiber optical parametric amplifier (OPA), the number of signal laser sources needed is only half of the number of
filter taps because new frequency components idlers are generated. Moreover, the free spectral range (FSR) of the
proposed filter can be changed by simply changing the wavelength spacing between the signals. In our experiment, an 8-
tap photonic microwave filter has been demonstrated using 4 signal laser sources, with FSR tuning range from 1.18 GHz
to 2 GHz which shows consistency between experimental and theoretical results.
We propose a method to realize frequency up-conversion of UWB monocycle pulse using pulsed-pump fiber optical
parametric amplifier (OPA). The spectrum of the amplified signal contains many discrete frequency components which
are separated by the modulation frequency of the pump. Each frequency components contain the same spectral
information as that of the original signal. By selecting the
first-order or higher-order frequency components of the
amplified signal and beating in the photodetector, up-converted signal at different frequencies are obtained. We
demonstrate frequency up-conversion of baseband UWB monocycle pulse from 3-GHz to 19-GHz in the experiment and
frequency up-conversion of pseudo-random binary sequence (PRBS) signal from 3-GHz to 60-GHz in the simulation.
An all-optical low-pass filter utilizing cross-gain modulation (XGM) in fiber optical parametric
amplifier (OPA) has been proposed and experimentally demonstrated. In this proposed low-pass filter,
the pump, signal and a continuous-wave probe were launched in the highly-nonlinear fiber (HNLF) to
introduce OPA and thereby XGM effects. Pump, signals and idlers were then being separated and then
filtered. With suitable time delay being introduced into different optical paths, the low-pass filter was
implemented, which was verified with the experimental results of pseudo-random signal. The timing
waveforms of the filtered signal were shown, followed by the transfer function of the low-pass filter's
frequency response. They all showed a good agreement with the numerical results.