Luxtera and TSMC have jointly developed a new generation 100Gbps/λ-capable silicon photonics platform in a commercial 300 mm CMOS line. We present process details and the performance of the photonic device library.
Bulk centrosymmetric silicon lacks second-order optical nonlinearity χ(2) - a foundational component of nonlinear optics.
Here, we propose a new class of photonic device which enables χ(2) as well as quasi-phase matching based on periodic
stress fields in silicon - periodically-poled silicon (PePSi). This concept adds the periodic poling capability to silicon
photonics, and allows the excellent crystal quality and advanced manufacturing capabilities of silicon to be harnessed for
devices based on χ(2)) effects. The concept can also be simply achieved by having periodic arrangement of stressed thin
films along a silicon waveguide. As an example of the utility, we present simulations showing that mid-wave infrared
radiation can be efficiently generated through difference frequency generation from near-infrared with a conversion
efficiency of 50% based on χ(2) values measurements for strained silicon reported in the literature [Jacobson et al. Nature
441, 199 (2006)]. The use of PePSi for frequency conversion can also be extended to terahertz generation. With
integrated piezoelectric material, dynamically control of χ(2)nonlinearity in PePSi waveguide may also be achieved.
The successful realization of PePSi based devices depends on the strength of the stress induced χ(2) in silicon. Presently,
there exists a significant discrepancy in the literature between the theoretical and experimentally measured values. We
present a simple theoretical model that produces result consistent with prior theoretical works and use this model to
identify possible reasons for this discrepancy.
The properties of glass-clad fibers containing cores of phase pure and highly crystalline
silicon and germanium are reviewed. Although further optimization is required, losses of about 4
dB/m have been achieved at 3 μm and suggest that such semiconductor core fibers could be of
practical value for nonlinear and infrared applications.
We report our latest experimental and numerical work on silicon microresonator passive and electro-optic active devices.
On the passive device front, we demonstrate an electrically tunable silicon microring notch filter for converting 3.6-Gbps
non-return-to-zero (NRZ) data format to return-to-zero (RZ)-like data format. We show that the converted RZ-like data
quality highly depends on the notch filter extinction ratios. On the active device front, we demonstrate a silicon
microring modulator using a double-coupled U-bend waveguide as a feedback and a pair of laterally integrated injectiontype
p-i-n diodes for bias/signal modulation. We show that the microring modulator extinction ratios are electrically
controlled by applying a DC-bias across either the feedback-waveguide or the microring while applying a modulation
signal across the other p-i-n diode. We also propose silicon microdisk modulators with selectively integrated depletiontype
Schottky diodes. Our numerical simulations suggest that the microdisk structures can be advantageous compared
with microring structures. We show that electrical rise time on the order of a few ps is feasible using microdisks. We
also allude to on-going work on extending the microresonator devices discussed here to building functional silicon
optoelectronics integrated circuits.
We experimentally demonstrate Fano resonance line shapes tuning by using a Mach-Zehnder interferometer (MZI). We employ a silica 125-μm-size hexagonal micropillar resonator with prism coupling in one arm of the interferometer, and a phase shifter together with a variable attenuator in the other arm. Our initial experiments reveal that the resonance line shapes observed at the interferometer output are characteristically asymmetric as Fano resonances. By using the phase shifter, we controllably tune the asymmetric line shapes from near-symmetric dip to near-symmetric peak and back to near-symmetric dip. We discuss potential applications of our MZI-based microresonator resonance line shapes tuning for bio-chemical sensing.