Optical Printed Circuit Board Research Articles

Experimental demonstration of 10?Gbit?s transmission with an optical backplane system using optical slots

A practical optical backplane system was prepared with transmitter-receiver processing boards and an optical backplane made from polymeric-waveguide-embedded optical printed-circuit boards. Optical slots were used as connection components between the transmitter-receiver processing boards and the backplane board to permit easy and repeatable insertion and extraction of the boards with micrometer precision. We report 10 Gbit/s data transmission between an optical backplane and the transmitter-receiver processing boards.

Improvement of fabrication yield and loss uniformity of waveguide mirror

Using a calculation of overlap integral loss of waveguide mirror was analyzed. According to this analysis method, a taper section was introduced and loss of deep ridge waveguide mirror was improved by 1.1 dB. Analysis shows that the most significant source of loss is the bevel angle of mirror facet. Also, using this method, improvement of fabrication yield and uniformity was obtained. This analysis and design method can be applied to mirrors for integrated photonic circuits and optical printed circuit board.

High-coupling-efficiency optical interconnection using a 90/spl deg/-bent fiber array connector in optical printed circuit boards

A high-coupling-efficiency optical interconnection has been demonstrated using a 90/spl deg/-bent fiber array connector to deflect beams between surface-emitting lasers or surface-receiving photodiodes and optical layers embedded in a board. A 90/spl deg/-bent fiber array is mounted in a tetragonal body with a millimeter scale size to make it suitable for passive packaging in the board. The bending radius of silica fibers in the connector was controlled to have 1.5 mm resulting in bending loss of about 0.5 dB. An optical link of 2.5-Gb/s signals with a total interconnection loss of -1.3 dB was demonstrated using the connectors and a fiber-embedded board.

PCB-Compatible Optical Interconnection Using 45<tex>$^circ$</tex>-Ended Connection Rods and Via-Holed Waveguides

In this paper, a new architecture for a chip-to-chip optical interconnection system is demonstrated that can be applied in a waveguide-embedded optical printed circuit board (PCB). The experiment used 45/spl deg/-ended optical connection rods as a medium to guide light paths perpendicularly between vertical-cavity surface-emitting lasers (VCSELs), or photodiodes (PDs) and a waveguide. A polymer film of multimode waveguides with cores of 100/spl times/65 /spl mu/m was sandwiched between conventional PCBs. Via holes were made with a diameter of about 140 /spl mu/m by CO/sub 2/-laser drilling through the PCB and the waveguide. Optical connection rods were made of a multimode silica fiber ribbon segment with a core diameter of 62.5 and 100 /spl mu/m. One end of the fiber segment was cut 45/spl deg/ and the other end 90/spl deg/ by a mechanical polishing method. These fiber rods were inserted into the via holes formed in the PCB, adjusting the insertion depth to locate the 45/spl deg/ end of rods near the waveguide cores. From this interconnection system, a total coupling efficiency of about -8 dB was achieved between VCSELs and PDs through connection rods and a 2.5 Gb/s /spl times/ 12-ch data link demonstrated through waveguides with a channel pitch of 250 /spl mu/m in the optical PCB.

MT-Compatible Laser-Ablated Interconnections for Optical Printed Circuit Boards

Integration of optical interconnections on a printed circuit board (PCB) is very challenging, since compatibility should be maintained with standard PCB manufacturing technology. This paper describes the use of laser ablation, a technique already used in PCB manufacturing for drilling microvias, as a suitable technique for the fabrication of multimode polymer waveguides, micromirrors, alignment features, and microlenses. A frequency-tripled Nd-YAG laser and a KrF excimer laser are used, both mounted on the same stage, resulting in very high alignment accuracies. This paper demonstrates a parallel optical link over approximately 5-cm-long PCB integrated waveguides, fully connected using a standard MT-based connector. This proves that laser ablation can be a key technology in optical board manufacturing to reach the stringent coupling tolerances.

10-Gb/s Data Transmission Experiments Over Polymeric Waveguides With 850-nm Wavelength Multimode VCSEL Array

A practical transmitter module was demonstrated, using a metal optical bench (MOB) and a tapered polymeric waveguide. The transmitter module was prepared for optical printed circuit board, which consists of the MOB, the driver chips, the vertical-cavity surface-emitting laser (VCSEL), and a tapered polymeric waveguide. We report a 10-Gb/s 2/sup 23/-1 pseudorandom bit sequence nonreturn-to-zero of data transmission from VCSEL to a multimode fiber block through a tapered polymeric waveguide. The tapered polymeric waveguide is fabricated with a large core size (100/spl times/60 /spl mu/m/sup 2/) by means of a hot embossing technique. The propagation loss of a tapered polymeric waveguide was approximately 0.1 dB/cm at 850 nm.

Board-to-Board Optical Interconnection System Using Optical Slots

A practical optical backplane system was prepared with transmitter-receiver processing boards and an optical backplane made of polymeric-waveguide-embedded optical printed-circuit boards. As connection components between the transmitter-receiver processing boards and backplane board, optical slots were used to enable easy and repeatable insertion and extraction of the boards with micrometer precision. We report an 8-Gb/s data transmission between transmitter processing board and optical backplane.

Low-crosstalk and high-efficiency optical interconnection using 45°-ended connection rods

A new architecture for an optical interconnection system that can be applied in a waveguide-embedded optical printed circuit board is demonstrated. 45°-ended optical connection rods were used to guide light paths perpendicularly between surface-emitting lasers (or photodiode) and waveguides. A 1.25 Gbit/s data link was successfully demonstrated.

Silicon optical printed circuit board for three-dimensional integrated optics

It is proposed that three-dimensional integrated optics make it possible to integrate various optical devices which are made of materials peculiar to their function. In a preliminary experiment, an optical printed circuit board has been fabricated with an Si substrate. The output light was taken out at an angle of 57.5 degrees upward from the surface of the substrate, and the propagation loss was 2.8 dB when the waveguide was 4.43 mm long.

Automatic Optical Inspection of Printed Circuit Boards

An automatic optical printed circuit board inspection machine will be described which provides considerable improvements on existing methods of PCB inspection and testing. The machine can detect breaks, nicks, shorts, pinholes, inadequate track clearances, inadequate track widths and holes which are undersized, oversized, missing or not concentric with the pad. It can be used in a non‐comparison mode to detect small defects in boards or photographic negatives, and can also be used in a comparison mode to provide a complete functional test of a board similar to that provided by a bed‐of‐nails tester, but with improved detection of marginal faults. The board is optically scanned and the resulting large amounts of data are reduced by special hardware and software techniques which allow rapid throughput and virtually eliminate ‘false alarms’ caused by lettering, logos, dust specks etc. which do not affect the functionality of the board. This technique differs considerably from the ‘Feature recognition’ and the ‘Comparison’ techniques at present employed in automatic optical PCB inspection. Operation of the machine is very simple as the board does not need to be accurately positioned, and a simple ‘good/bad’ indication is provided as well as more detailed defect location information.