Osamu Ibaragi

Laser-written optical-path redirected waveguide device for optical back-plane interconnects

A novel optical-path redirected three-dimensional waveguide device for optical back-plane interconnects is demonstrated. To fabricate an optical waveguide device, a laser-written technique using focused irradiation of visible femtosecond pulses is employed. In this waveguide device, single-stroke drawing is applied for low-cost fabrication. To redirect the optical path, a planar reflective mirror was adopted. Since the focus of the laser was shifted successively while drawing cores in glass substrate, multichannel optical cores were continuously written up to the surface component. By having this structure, back-plane interconnects can be integrated more densely, and an optical back-plane board can be coupled to a daughter-board directly without any microlenses. Furthermore, all cores have the same length, so this device potentially suppresses the modulation skew caused by the difference of optical-path lengths. We present the fabrication and the test results of a glass-based waveguide device for optical-path redirection.

Optical component coupling using self-written waveguides

The titled method has been systematically studied to improve existing alignment control difficulties between optical components to be coupled. Using UV curable resin as a waveguide material, UV cured optical waveguide is “self-written” by UV exposure from an edge of optical fiber. So far we have shown that this method is very effective for optical fibers coupling under existence of gap and offset. We tried here to couple different optical circuit using polymer optical waveguide. One key technique to produce a self-written waveguide from a polymer waveguide is to use visible light curable resin instead of so far used UV curable resin in which self-written waveguide hardly forms because of strong UV absorption of the polymer waveguide. Similar coupling loss is also obtained for polymer waveguide/optical fiber coupling as well as so far studied optical fibers coupling. Clad stabilizing process in the optical fiber coupling is also optimized to decrease coupling loss. The obtained coupling loss is less than 1 dB for 500 um gap; the value is significantly lower than the previously reported value, > 2 dB. Using this unique and easy coupling method, significant cost reduction can be expected in optical coupling procedure.

Optical path redirected three-dimensional lightguide connectors for high-speed interconnection modules

Increasing demands for communication bandwidth are driving the need for low-cost and integrated connectivity in optical network systems. In this paper, we describe one solution for implementation of cost effective and highly integrated optical interconnects. VCSEL/PD are suited for optical interconnects because they are able to make two-dimensional arrays for higher-integration. This paper describes two-type novel lightguide connectors for VCSEL/PD. The concepts of these connectors are as follows: (1) matrix arrayed multi-channel optical I/Os and optical path redirection for efficient coupling to 50 /spl mu/m diameter multi-mode fiber, (2) connectivity to commercially available multi-channel connectors, (3) low cost fabrication, (4) high-speed transmission performance. In order to meet these concepts, we proposed three-dimensional lightguide devices having matrix arrayed cores and reflective mirror for optical path redirection. By using these lightguide devices, pigtail connectors were fabricated for cost reduction and down sizing of the connector volumes. Receptacle connectors with fully compatibility to surface mount technology (SMT) were fabricated to have great advantages for low cost and mass production. Both connectors can be coupled to commercially available MT connectors and have sufficient high-speed transmission performance. These connectors have the potential to achieve low cost fabrication and higher integration in the optical interconnects.

Implementation of active interposers for extremely high-definition display

This paper demonstrates a novel high-definition (HD) display system using the optical interconnection technique. This system features a 20-million-pixel 40-in thin film transistor (TFT) liquid crystal display (LCD) comprising four 20-in LCDs each with five million pixels. A four-channel optical interconnection module, called an active interposer, was employed to transmit graphical data consisting of red, green, blue, and clock signals. For efficient coupling with multimode fibers and to effect a compact coupling structure, three-dimensional (3-D) waveguide arrays with two-dimensionally (2-D) integrated optical input/output and optical path redirection to the pigtail connectors of the active interposer were applied. This paper also employed eight transmitter (Tx) and receiver (Rx) active interposers and 50-m multimode fibers in the system, and with 32-channel parallel optical data transmission successfully displayed HD pictures on the LCD. The results indicate that active interposers are suitable for graphical data transmission and show promise for future applications that use the optical interconnection technique.