Low-cost, precision, self-alignment technique for coupling laser and photodiode arrays to polymer waveguide arrays on multilayer PCBs

The first, to our knowledge, passive, precision, self-alignment technique for direct coupling of vertical cavity surface emitting laser (VCSEL) and photodiode (PD) arrays to an array of polymer buried channel waveguides on a rigid printed circuit board (PCB) is reported. It gives insertion losses as good as the best achieved previously, to within experimental measurement accuracy, but without the need for costly active alignment nor waveguide facet polishing and so is a major step towards a commercially realizable low cost connector. Such an optical connector with four duplex channels each operating at 10 Gb/s (80 Gb/s aggregate) was designed, constructed, and its alignment precision assessed. The alignment technique is applicable to polymer waveguide interconnections on both rigid and flexible multilayer printed circuit boards (PCBs). The dependence of optical coupling loss on mis-alignments in x, y and z of the VCSEL and PD arrays allows the precision of alignment to be assessed and its reproducibility on multiple mating cycles of the connector is reported. The first recorded measurements of crosstalk between waveguides when the connector is misaligned are reported. Lateral misalignments of the connector to within its tolerance are shown to have no effect on the signal to crosstalk ratio (SCR), to within experimental measurement accuracy. The insertion loss repeatability is similar to that of single mode fiber mechanically transferable (MT) connectors

Optical Printed Circuit Board and Connector Technology, 9th October 2010 afternoon

1.5 hour tal

Optical Waveguide End Facet Roughness and Optical Coupling Loss

This paper investigates the end facet roughness of multimode polymer channel waveguides fabricated on FR4 printed circuit boards, PCBs, when cut at right angles to their optical axis by milling routers for optical butt-coupling connectors and compares it with that resulting from dicing saws and polishing and proposes a novel end facet treatment. RMS surface roughness of waveguide end facets, measured by AFMs, are compared for a range of rotation speeds and translation speeds of a milling router. It was found that one-flute routers gave significantly less rough surfaces than two or three-flute routers. The best results were achieved for a one-flute router when the milling bit was inserted from the PCB side of the board with a rotation speed of 15,000 rpm and a translation speed of 0.25 m/min which minimized the waveguide core end facet RMS roughness to 183 ± 13 nm and gave input optical coupling loss of 1.7 dB ± 0.5 B and output optical coupling loss of 2.0 dB ± 0.7 dB. The lowest RMS roughness was obtained at chip loads of 16 μm/revolution. High rotation speeds should be avoided as smearing of the end facet occurs possibly due to polymer heating and softening. For the first time to our knowledge, channel waveguide optical insertion loss is shown to be linearly proportional to the ratio of the waveguide core end facet RMS roughness to its autocorrelation length. A new fabrication technique for cut waveguide end facet treatment is proposed and demonstrated which reduces the insertion loss by 2.60 dB ± 1.3 dB which is more than that achieved by the closest available index matching fluid which gave 2.23 dB ± 1.2 dB. The new fabrication method gives a more robust end facet for use in commercial products

FirstLight: Pluggable Optical Interconnect Technologies for Polymeric Electro-Optical Printed Circuit Boards in Data Centers

The protocol data rate governing data storage devices will increase to over 12 Gb/s by 2013 thereby imposing unmanageable cost and performance burdens on future digital data storage systems. The resulting performance bottleneck can be substantially reduced by conveying high-speed data optically instead of electronically. A novel active pluggable 82.5 Gb/s aggregate bit rate optical connector technology, the design and fabrication of a compact electro-optical printed circuit board to meet exacting specifications, and a method for low cost, high precision, passive optical assembly are presented. A demonstration platform was constructed to assess the viability of embedded electro-optical midplane technology in such systems including the first ever demonstration of a pluggable active optical waveguide printed circuit board connector. High-speed optical data transfer at 10.3125 Gb/s was demonstrated through a complex polymer waveguide interconnect layer embedded into a 262 mm × 240 mm × 4.3 mm electro-optical midplane. Bit error rates of less than 10-12 and optical losses as low as 6 dB were demonstrated through nine multimode polymer wave guides with an aggregate data bandwidth of 92.8125 Gb/s

Optical Wavelength Division Multiplexed Multiplexer/Demultiplexer for an Optical Printed Circuit Board and a Method of Manufacturing the Same

The invention provides an optical mux/demux for an optical printed circuit board. The mux/demux comprises: a first waveguide formed on a support layer for carrying a wavelength division multiplexed optical signal; a separator/combiner for separating the wavelength division multiplexed signal into component signals of corresponding wavelengths or for combining component signals into the said wavelength division multiplexed signal; and plural second waveguides, each for receiving or providing one or more of the said component signals, wherein the separator/combiner is at a predetermined location relative to the waveguides. 37 CFR Sec 3.2 US Provisional Application Serial number 60/847,40

Optical printed circuit board and connector technology

Presentation to Dr Mike Gurreri, Dr Stephane Berghmans, Davy Brown, Jan Watte, Koen Verweyen, TE Connectivity at UC

Optical printed circuit board and manufacturing method

The invention provides a method of manufacturing an optical printed circuit board and an optical printed circuit board. The method comprises providing a support layer; on the support layer, providing an optical core layer; forming optical channels from the optical core layer and surrounding the optical channels with cladding thereby forming optical waveguides; and during said step of forming the optical channels, forming one or more alignment features (e.g. projections) on the optical printed circuit board. The invention provides a method of manufacturing an optical printed circuit board and an optical printed circuit board. The method comprises providing a support layer; on the support layer, providing an optical core layer; forming optical channels from the optical core layer and surrounding the optical channels with cladding thereby forming optical waveguides; and during said step of forming the optical channels, forming one or more alignment features (e.g. projections) on the optical printed circuit board

Passive assembly of parallel optical devices onto polymer-based optical printed circuit boards

Purpose - The purpose of this paper is to present the latest results from research and development into future optical printed circuit board (OPCB) interconnects and low-cost assembly methods.Design/methodology/approach - A novel method of high-precision passive alignment and assembly to OPCBs was invented and a full evaluation platform developed to demonstrate the viability of this technique.Findings - The technique was successfully deployed to passively align and assemble a lens receptacle onto an embedded polymer waveguide array in an electro-OPCB. The lens receptacle formed a critical part of a dual lens pluggable in-plane connection interface between peripheral optical devices and an OPCB. A lateral in-plane mechanical accuracy of +/- 2 mu m has been measured using this technique.Research limitations/implications - As this is a free space optical coupling process, surface scattering at the exposed waveguide end facet was significant.Originality/value - This paper details a novel method of passively assembling arbitrary optical devices onto multi-mode optical waveguides and outlines the procedure and equipment required. A lens coupling solution is also presented which reduces susceptibility of a connecting optical interface to contamination