Craig M. Hill

CMOS-Compatible Si-Ring-Assisted Mach–Zehnder Interferometer With Internal Bandwidth Equalization

We demonstrate, to the best of our knowledge, the first electrooptic ring-assisted Mach-Zehnder interferometric (RAMZI) modulator in a CMOS-compatible technology. The RAMZI modulator is manufactured on a CMOS-compatible platform and entirely fabricated in a commercial CMOS foundry. We demonstrate a small-signal 3-dB bandwidth >15 GHz in a silicon-based carrier-depletion modulator with a 2-V·cm V¿L product, which is approximately two times smaller than previously reported. We achieved a 10-Gb/s eye diagram with a 2-dB extinction ratio using a 4-Vp-p drive in a modulator with a 680-¿m optic/RF interaction region. In addition, we demonstrate internal bandwidth equalization within the tunable CMOS-compatible RAMZI modulator, and discuss the optical carrier and modulation sideband response, and relaxation characteristics that lead to this behavior within resonant modulators.

Demonstration of a fast-reconfigurable silicon CMOS optical lattice filter

We demonstrate a fully-reconfigurable fourth-order optical lattice filter built by cascading identical unit cells consisting of a Mach-Zehnder interferometer (MZI) and a ring resonator. The filter is fabricated using a commercial silicon complementary metal oxide semiconductor (CMOS) process and reconfigured by current injection into p-i-n diodes with a reconfiguration time of less than 10 ns. The experimental results show full control over the single unit cell pole and zero, switching the unit cell transfer function between a notch filter and a bandpass filter, narrowing the notch width down to 400 MHz, and tuning the center wavelength over the full free spectral range (FSR) of 10 GHz. Theoretical and experimental results show tuning dynamics and associated optical losses in the reconfigurable filters. The full-control of each of the four cascaded single unit cells resulted in demonstrations of a number of fourth-order transfer functions. The multimedia experimental data show live tuning and reconfiguration of optical lattice filters.

Low-loss asymmetric strip-loaded slot waveguides in silicon-on-insulator

We report on low-loss asymmetric strip-loaded slot waveguides in silicon-on-insulator fabricated with 248 nm photolithography. Waveguide losses were 2 dB/cm or less at wavelengths near 1550 nm. A 40 nm strip-loading allows low-resistance electrical contact to be made to the two slot arms. The asymmetric design suppresses the TE1 mode while increasing the wavelength range for which the TE0 mode guides. This type of waveguide is suitable for building low insertion-loss, high-bandwidth, low drive-voltage modulators, when coated with an electro-optic polymer cladding.

Photolithographically fabricated low-loss asymmetric silicon slot waveguides.

We demonstrate low-loss asymmetric slot waveguides in silicon-on-insulator (SOI). 130 and 180 nm wide slots were fabricated with a 248 nm stepper, in 200 nm thick silicon. An asymmetric waveguide design is shown to expand the range in which the TE0 mode is guided and suppress the TE1 mode, while still maintaining a sharp concentration of electric field in the center of the slot. Optical propagation losses of 2 dB/cm or less are shown for asymmetric slot waveguides with 130 nm wide slots and 320 and 100 nm wide arms.

Waveguide-Integrated Ge p-i-n Photodetectors on SOI Platform

We demonstrate a fully CMOS processed Ge p-i-n photodetector integrated with a Si waveguide on a SOI platform with a high responsivity of 1.0 A/W at lambda=1520 nm, and a 3 dB bandwidth of >4.5 GHz measured at lambda=1550 nm

Waveguide Integrated Ge p-i-n Photodetectors on a Silicon-on-Insulator Platform

We present selectively grown Ge p-i-n photodetectors coupled to high index contrast Si(core)/SiO2(cladding) waveguides on a silicon-on-insulator (SOI) platform. Two coupling schemes, namely butt-coupling and vertical coupling, were demonstrated in this study. With the butt-coupling scheme we have achieved a high responsivity of 1.0 A/W at 1520 nm and a 3 dB bandwidth greater than 4.5 GHz at 1550 nm. With the vertical coupling scheme, where the light couples from a Si waveguide evanescently to the Ge detector on top of it, a responsivity of 0.22 A/W and a 3 dB bandwidth of ~1.5 GHz have been demonstrated at 1550 nm. The devices were fabricated on a standard 180 nm industrial complementary metal oxide semiconductor production (CMOS) line, and can be integrated with CMOS circuitry for electronic and photonic integrated circuits

Ultra-thin silicon-on-insulator strip waveguides and mode couplers

We demonstrate an ultra-thin silicon waveguide for wavelengths around 1.55 μm, and mode converters designed for transitions to and from standard 500 nm × 220 nm strip waveguides. The devices were fabricated in a CMOS-compatible process requiring two photolithography and etch steps. The ultra-thin waveguides exhibited losses of 2.01 ± 0.231 dB/cm, exhibited bend radii as small as 30 μm with losses of 0.05 ± 0.005 dB per bend, and exhibited coupling losses of 0.66 ± 0.014 dB to standard strip waveguides.

Shared shuttles for integrated silicon optoelectronics

Shared shuttle runs are an important factor of the microelectronics business ecosystem, allowing fabless semiconductor companies to access advanced processes and supporting the development of new tools and processes. We report on the creation and progress of a shared shuttle program for access to advanced silicon photonics optoelectronic platforms that we expect will create a similar environment for the field of integrated photonics.

Asymmetric strip-loaded slot waveguides and its applications in silicon-polymer hybrid electro-optic modulators

A new class of electrically contactable slot waveguides are discussed regarding its unique advantages for building high-performance electro-optic modulators. 2dB/cm waveguide losses near 1550nm were achieved with devices fabricated in silicon-on-insulator with 248nm photolithography.