The package integration of optical components with electronic integrated circuits
(ICs) for optical interconnects is a subject of much debate and will, to a large extent,
determine the performance of the optical interconnect system. In this paper we examine
the challenges of incorporating optical interconnects into a computer system; specifically
we cover several ways to integrate the optical components with a central processing
unit (CPU) or chipset.
Critical performance parameters such as the supported distance, power
consumption and the achievable bandwidth are all impacted by the electrical integration
between the IC and the optical components. Additional electrical link issues which also
have a large impact on the performance of the link will be discussed as well; these include
protocol related issues as well as signal integrity concerns, such as the jitter budget.
We will also discuss the performance of some of the competing electrical
technologies in order to provide a better understanding of the implementation challenge
facing the developers of optical interconnect technology. Rack to rack communications
are quickly moving to optical links, board to board communication is the next step and chip
to chip communication is still further out as the electrical solutions for this topology have a
great deal of headroom.
Monolithic wavelength-graded vertical-cavity surface- emitting laser (VCSEL) and wavelength-selective resonance enhanced photodetector (REPD) arrays have been developed for use in wavelength-division multiplexed optical interconnect architectures. The aim is to achieve a cost-effective wavelength-multiplexed optical interconnect that can carry a large amount of data over longer distances using a single optical fiber. A controllable means for producing wavelength-graded VCSEL and REPD arrays is described, based on the topography-controlled MOCVD growth on a patterned substrate. This technique allows the growth rate of all the epilayers to be scaled, thereby providing closer tracking of the reflectance peak and the gain peak and resulting in more uniform device characteristics. VCSELs and REPDs have been monolithically integrated using the same epilayer structure and the same growth technique. This paper focuses on (1) the characteristics of oxide-confined multi-wavelength VCSEL arrays, (2) the design and comparison of optimized REPD structures at 850 nm and at 980 nm, and (3) wavelength multiplexing and demultiplexing using VCSEL and REPD arrays.
Monolithic, uniformly-wavelength-graded, vertical-cavity surface- emitting laser (VCSEL) and wavelength-selective resonance- enhanced photodetector (REPD) arrays are key enabling technologies for many wavelength-multiplexed optical network and interconnect architectures. These arrays can be produced in a repeatable and uniform manner by controlling the local MOCVD growth rate of the epilayers on a topographically patterned substrate, which resulted in wavelength-differentiated devices with more uniform optical characteristics. Multi-wavelength VCSEL and REPD arrays have been monolithically integrated on the same substrate to improve the wavelength matching between the source and detector elements. The performance characteristics of these arrays are discussed. We also describe a wavelength-division- multiplexing and demultiplexing experiment in which several channels of optical data are multiplexed together using a multi- wavelength VCSEL array and transmitted on a single optical fiber, and are demultiplexed at the other end using a wavelength- selective REPD array with closely-matching wavelengths.
Recent advances in the design of high-speed optical switches and transceivers for a reconfigurable, spatially-multiplexed optical interconnection network are described. Monolithic switches based on the integration of vertical-cavity surface-emitting lasers with heterojunction bipolar transistors and photodetectors have achieved switching operation at a data rate of close to 1 Gb/s. Optical transmission experiments through fibers have been carried out using these switches at a data rate between 650 Mb/s and 1 Gb/s. For future improvements in performance, the photonic and electronic elements should be separately integrated and independently optimized. To facilitate photonic integration, VCSELs and resonance-enhanced photodetectors have been integrated on the same substrate.
We review our progress in the development of an optical interconnect technology consisting of optical and optoelectronic switches that integrate vertical-cavity surface-emitting lasers (VCSELs) with other photonic and electronic components, including heterojunction phototransistors (HPTs) and heterojunction bipolar transistors (HBTs). We describe a reconfigurable multi-access optical network architecture that allows many high speed electronic processors to simultaneously communicate with each other and with other shared resources, and for its implementation, an integrated optoelectronic switching technology that combines the functions of an optical transceiver and a spatial routing switch. The network provides parallel and dynamically reconfigurable optical interconnections between nodes, as well as optoelectronic interfaces to each processor. By converting data between the electrical and optical formats, these multi-functional switches can receive or transmit optical data, or to bypass and re-route it to another node. Optical switching has been demonstrated experimentally at a data rate of 200 Mb/s, and electrical-to-optical data conversion has been achieved at a data rate of > 500 Mb/s.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.