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Browse Prior Art Database

TCM Optical Clock/ Data Distribution Arrangements With Multiplexed Holograms

IP.com Disclosure Number: IPCOM000122682D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 6 page(s) / 179K

Publishing Venue

IBM

Related People

Gallo, AR: AUTHOR [+6]

Abstract

Disclosed are two holographic schemes for TCM (Thermal Conduction Module) optical clock or data distribution for removing or minimizing the difficulties, such as clock skew and noise problems, in high-speed operations to achieve better performance.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 51% of the total text.

TCM Optical Clock/ Data Distribution Arrangements With Multiplexed
Holograms

      Disclosed are two holographic schemes for TCM (Thermal
Conduction Module) optical clock or data distribution for removing or
minimizing the difficulties, such as clock skew and noise problems,
in high-speed operations to achieve better performance.

      A TCM module houses a multilayer ceramic substrate and can cool
100 or more chips mounted on its surface.  The parts of TCM above the
chips are used for dissipating heat generated by the chips and have
no room for introducing an optical clock signal.  We then have two
possible arrangements: Scheme 1, optical clock/data signal inputs
from the bottom of the substrate (Fig. 2); and Scheme 2, optical
clock/data signal inputs from one side or several sides of the
substrate (Fig. 3).  For some other kinds of cooling technology
(e.g., air cooling), the optical clock/data signal may be able to
input from the top of the module or directly to the chips. In this
case, the arrangements in Scheme 1 (as shown in Fig. 1) can be used
also, except that the hologram(s) are placed in the top and the
optical clock/data signal is applied from the top.

      Scheme 1.  The optical clock/data signal, generated from an
optical source, inputs from  the bottom of the substrate and is then
distributed by a multiplexed bulk phase hologram (Fig. 2(a)) or by
levels of multiplexed multifacet holograms (Fig. 2(b)).  A detector
array is embedded in the bottom of the substrate, and the clock/data
signal is then transformed from optical signal into electric signal.
The metallic links within the substrate pass the optical signal to
the chips. If we have to distribute clock/data signal into N chips,
we should use a multiplexed bulk hologram with N gratings; each
holographic grating will distribute about 1/N input optical energy
into a detector. The number of gratings that can be stored in a
hologram depends on the thickness of the hologram, as discussed
later. If the number of chips is larger than the number of gratings
we can provide, we may need hierarchical levels of holograms.  For
example, if we have K2 chips to receive the optical clock/data and
one hologram can provide only K gratings, then we need two holograms:
the first hologram near the optical source diffracts an input optical
signal into K different beams, each beam connecting to a subhologram
(i.e. one facet) of the sec...