Ekkehard Klement

Optical multichannel parallel chip-to-chip data distribution

The design and the modelling results of an 8 channel parallel optical chip to chip interconnection consisting of a laser diode (LD) array, a single-mode waveguide (WG) array, and a photodiode (PD) array with 8 channels each are presented. The separation of the channels is 125 im, so the overall width of the 8 channel line is only I mm. The electronic and the optoelectronic components will be mounted on a silicon substrate wafer and the waveguides on a second silicon wafer which will be fixed upside down on the substrate. The LDs are envisaged to be AlGaAs singlequantum well types though the first implementation will be realized with conventional A1GaAs MCRW semiconductor lasers with a wavelength of 0.85 rim. The PDs are fabricated in standard silicon technology, the silica WGs with the flame hydrolysis technique and reactive ion etching. The trade off between large fabrication tolerances and the desired high coupling efficiencies is discussed. Mounting techniques for the LD- and PD-arrays are presented. A comparison between this optical interconnection and an equivalent electrical one is given.

Holographic optical elements for free-space clock distribution

Optical clock distribution is an attractive technique to avoid clock skew in highspeed digital systems. For short lengths free space distribution by holographic optical elements (HOE) has specific advantages. We will report on the requirements of the optical system in respect of necessary light power and its equipartition to the photoreceivers. We give an estimation for the maximum number for optical fanout con sidering especially ECL circuits. Specific system constraints lead to a certain layout for the whole arrangement. The realization of a distinct HOE type is carried out in form of a binary phase reflection HOE which is produced by dry etching of silicon. The measured diffraction efficiency is close to the theoretical limit.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Clock distribution using a synthetic HOE with multiple fan-out at IR-wavelength

We report about the design of an optical intrachip clock distribution using an IR-laser diode 1 ocated at one edge of an electronic chip and 4 on-chip photoreceivers, all components connected via a reflective HOE. The high divergence angle of the laser beam and its oblique incidence onto the HOE together wfth the 4 fan-out directions require HOE-feature sizes which are in the order of the operation wavelength X0.86 tm. This study considers both multiplex and multifacet computer-generated HOEs . The pattern complexity, the respective pattern resolutions, the beam rouung abilities and the spot quality of the focused output beams are discussed. A calculation method for the estimation of the alignment tolerances is explained and the results will show that our arrangement is feasible using mounting techniques based on micromechanics in preferential etched silicon.