In this project we endeavored to improve the state-of-the-art in UV lasers diodes. We made important advancements in several fronts from modeling, to epitaxial growth, to fabrication, and testing. Throughout the project it became clear that polarization doping would be able to help advance the state of laser diode design in terms of electrical performance, but the optical design would need to be investigated to ensure that a 2D guided mode would be supported. New capability in optical modeling using commercial software demonstrated that the new polarization doped structures would be viable. New capability in pulsed testing was established to reach the current and voltage required. Our fabricated devices had some parasitic electrical paths which hindered performance that we were ultimately unable to overcome in the project timeframe. We do believe that future projects will be able to leverage the advancements made under this project.
Heterogeneous Integration (HI) may enable optoelectronic transceivers for short-range and long-range radio frequency (RF) photonic interconnect using wavelength-division multiplexing (WDM) to aggregate signals, provide galvanic isolation, and reduce crosstalk and interference. Integration of silicon Complementary Metal-Oxide-Semiconductor (CMOS) electronics with InGaAsP compound semiconductor photonics provides the potential for high-performance microsystems that combine complex electronic functions with optoelectronic capabilities from rich bandgap engineering opportunities, and intimate integration allows short interconnects for lower power and latency. The dominant pure-play foundry model plus the differences in materials and processes between these technologies dictate separate fabrication of the devices followed by integration of individual die, presenting unique challenges in die preparation, metallization, and bumping, especially as interconnect densities increase. In this paper, we describe progress towards realizing an S-band WDM RF photonic link combining 180 nm silicon CMOS electronics with InGaAsP integrated optoelectronics, using HI processes and approaches that scale into microwave and millimeter-wave frequencies.
The design, fabrication, and performance of InGaAs and InGaP/GaAs microcells are presented. These cells are integrated with a Si wafer providing a path for insertion in hybrid concentrated photovoltaic modules. Comparisons are made between bonded cells and cells fabricated on their native wafer. The bonded cells showed no evidence of degradation in spite of the integration process that involved significant processing including the removal of the III-V substrate.
Optical diagnostics play a central role in dynamic compression research. Currently, streak cameras are employed to record temporal and spectroscopic information in single-event experiments, yet are limited in several ways; the tradeoff between time resolution and total record duration is one such limitation. This project solves the limitations that streak cameras impose on dynamic compression experiments while reducing both cost and risk (equipment and labor) by utilizing standard high-speed digitizers and commercial telecommunications equipment. The missing link is the capability to convert the set of experimental (visible/x-ray) wavelengths to the infrared wavelengths used in telecommunications. In this report, we describe the problem we are solving, our approach, our results, and describe the system that was delivered to the customer. The system consists of an 8-channel visible-to- infrared converter with > 2 GHz 3-dB bandwidth.
Layer disordering and doping compensation of an Al0.028Ga0.972N/AlN superlattice by implantation are demonstrated. The as-grown sample exhibits intersubband absorption at ∼1.56 μm which is modified when subject to a silicon implantation. After implantation, the intersubband absorption decreases and shifts to longer wavelengths. Also, with increasing implant dose, the intersubband absorption decreases. It is shown that both layer disordering of the heterointerfaces and doping compensation from the vacancies produced during the implantation cause the changes in the intersubband absorption. Such a method is useful for removing absorption in spatially defined areas of III-nitride optoelectronic devices by, for example, creating low-loss optical waveguides monolithically that can be integrated with as-grown areas operating as electro-absorption intersubband modulators.