Quantum dot comb sources integrated with silicon photonic ring-resonator filters and modulators enable the realization of optical sub-components and modules for both inter- and intra-data-center applications. Low-noise, multi-wavelength, single-chip, laser sources, PAM4 modulation and direct detection allow a practical, scalable, architecture for applications beyond 400 Gb/s. Multi-wavelength, single-chip light sources are essential for reducing power dissipation, space and cost, while silicon photonic ring resonators offer high-performance with space and power efficiency.
Widely tunable mid infrared radiation achievable using quantum cascade lasers (QCLs) often
requires external cavities and several QCL chips to cover a large bandwidth similar to the range
reported here (~ 1000s nm). The cost and mechanical stability of these designs leaves room for
alternative more rugged approaches, which require no cavities to achieve very broad band tunability.
While difference frequency generation (DFG) will unlikely match the power levels achievable from
QCLs, it can provide spectral brightness and extremely wide tunablity, which can be valuable for
Recently, we have demonstrated that dispersion engineering techniques can be used for phase
matching of second order nonlinearities near the bandgap in monolithic waveguides. In this work we
demonstrate an extremely simple structure to grow and fabricate, which utilizes dispersion
engineering not only to achieve phase matching but also to expand the tuning range of the frequency
conversion achieved in a waveguide through difference frequency generation. Frequency conversion
in monolithic AlGaAs single-sided Bragg reflection waveguides using<i> χ<sup>(2)</sup> </i>nonlinearities produced
widely tuneable, coherent infrared radiation between 2-3 μm and 7-9 μm. The broad tunability
afforded by dispersion engineering and possible current injection, waveguide width chirping and
temperature tuning makes it possible to produce a single multi-layer substrate to generate mid-IR
signals that span μms in wavelength.
An effective approach to achieve efficient phase matching for second order nonlinearities, in
multilayer structures will be discussed. It uses dispersion engineering in Bragg reflection waveguides
to harness parametric processes in conjunction with concomitant dispersion and birefringence
engineering in active devices. This technology enables novel coherent light sources using frequency
conversion in a self-pumped chip form factor. These sources can also provide continuous coverage of
spectral regions, which are not accessible by other technologies including quantum cascade lasers.
This approach has been recently demonstrated in multi-layer Silicon-Oxy-Nitride (SiON) waveguides.
Harnessing χ<sup>(2)</sup> in SiON offers a route for integration of broadband infrared sources using frequency
mixing with opto-fluidics. Different approaches for implementing opto-fluidic structures on Si will be
discussed, where the root cause of enhancing the retrieved Raman and infrared signals in these
structures will be explained. Recent progress in using this approach to study different nanostructures
and biological molecules will be presented.
In this paper we will describe the fabrication and characterization of passive waveguides which exploit the phenomenon
of variable charge state mediation of deep-levels in silicon to vary optical absorption. Silicon waveguides are doped with
either thallium or indium and co-doped with phosphorus. Optical absorption is reduced s phosphorus doping is increased.
These results suggest a novel method of modulation via charge-state control of the deep-level.
In this paper we outline recent results which combine defect mediated Photo-Detectors (PDs) in a Ring Resonator (RR)
structure. By exploiting the multiple-pass of the optical signal through the detector, we are able to significantly decrease
the size of the detector structure while maintaining good responsivity (typically 0.1 A/W). In such a geometry the
detector bandwidth is not capacitance limited, while the leakage current is reduced toward 1 nA. We also show that these
PDs may be used in the drop port of a RR to monitor the propagating signal. These devices have applicability in
multiplexing and potential for integration with high speed modulation functionality.
We have devised and fabricated high-speed silicon-on-insulator resonant microring photodiodes. The detectors comprise a p-i-n junction across a silicon rib waveguide microring resonator. Light absorption at 1550 nm is enhanced by implanting the diode intrinsic region with boron ions at 350 keV with a dosage of 1 × 1013 cm−2. We have measured 3-dB bandwidths of 2.4 and 3.5 GHz at 5 and 15 V reverse bias, respectively, and observed an open-eye diagram at 5 gigabit/s with 5 V bias.
It is now established that defects introduced via ion implantation may act as generating centers in silicon waveguide
structures and consequently enhance photosensitivity at wavelengths in the region of 1550 nm. Although several
integrated p-i-n waveguide photodiode structures have been presented which exploit this behavior, no attempt has been
made to model the generation process and thus optimize device design. We report a model that has been implemented
using SILVACO's ATLAS software, and reproduces the observed behavior in the aforementioned device structures. By
varying parameters such as the dimensions of the device and the implantation conditions, the responsivity can be
maximized. In particular, we have designed an integrated structure centered on a 3 µm wide waveguide created by the
LOCOS (Local Oxidation of Silicon) technique on lightly p-doped Silicon-on-Insulator. A self aligned n+ polysilicon
contact is placed above the ridge, causing the majority of the depletion to overlap with the optical mode. Symmetric p+
regions are placed on either side of the waveguide, separated by a distance selected to optimize responsivity without
causing excess loss. This presents a vast improvement over previous structures of its size, having a predicted
responsivity in excess of 50 mA/W at a 2V reverse bias.