A practical optical link system was prepared with a transmitter (Tx) and receiver (Rx). The optical TRx module
consisted of a metal optical bench, a module printed circuit board (PCB), a driver/receiver IC, a VCSEL/PD array, and
an optical link block composed of plastic optical fiber (POF). For the optical interconnection between the light-sources
and detectors, an optical wiring method has been proposed to enable easy assembly.
This paper provides a method for optical interconnection between an optical Tx and an optical Rx, comprising the
following steps: (a) forming a light source device, an optical detection device, and an optical transmission unit on a
substrate (metal optical bench (MOB)); (b) preparing a flexible optical transmission-connection medium (optical wiring
link) to optically connect the light source device formed on the substrate with the optical detection device; and (c)
directly connecting one end of the surface-finished optical transmission connection medium with the light source device
and the other end with the optical detection device. A chip-to-chip optical link system constructed with TRx modules
was fabricated and the optical characteristics were measured. The results clearly demonstrate that the use of an optical
wiring method can provide robust and cost-effective assembly for vertical-cavity surface-emitting lasers (VCSELs) and
photodiodes (PDs). We successfully achieved a 5 Gb/s data transmission rate with this optical link.
The cost-effective and repeatable technology for integration of polymer multimode waveguide and out-of-plane 45° reflector mirrors is developed. This method is cost-effective, repeatable, robust, and fully compatible with the standard manufacturing processes for a 90° optical bending structure.
The basic concept of the technology for integration of waveguide and out-of-plane 45° reflector mirrors is as follows; 1) The positively patterned master in order to mold waveguides is manufactured by using photolithography and Deep RIE (Reactive Ion Etching). And the master is polished to obtain 45°-inclined plane. 2) Both sides of the positively patterned master are divided into three parts by using a sawing machine. One is a center master (main-master) with a positively patterned waveguide and the others are side masters (sub-master) without a pattered waveguide. The main master and sub-master turned over get back together again. 3) The negatively patterned PDMS master to be able to mold simultaneously both waveguide and out-of-plane 45° reflector mirrors is manufactured through pouring PDMS gel into master and thermally curing the PDMS master. 4) The multimode tapered waveguides with out-of-plane 45° reflector mirrors are simultaneously embossed by using PDMS master. The UV (Ultraviolet) curable material is organic-inorganic hybrid material (HYBRIMER, core index: 1.51, clad index: 1.48).
The transmitter module is constructed on a MOB. The MOB was employed for several purposes; to align optical module passively, to use as heat sinker and also to support the boards. On this MOB, 1×4 arrays of vertical-cavity surface-emitting laser (VCSEL) and Tapered Waveguide with 45° reflector mirrors are integrated. The height and width of waveguide's core are 100 μm, 60 μm respectively and the pitch is 250 μm. The transmission access lines in transmitter are designed considering differential impedance matching for high-speed operation. We measured the insertion loss of this transmitter module using a 62.5 μm graded index fiber. The average insertion loss value is roughly about 7dB.
In this paper, we describe the cost-effective and simplified fabrication of an index modulation type buried waveguide using laser direct writing. Our studies have a potential of manufacturing waveguides on an uneven surface and a large area because there is no need for photo-mask, etching and development processes. We used organic-inorganic hybrid materials (HYBRIMER) for the fabrication of the waveguides, which have a high transparency from a visible region to an infrared region. We exposed the core layer (HYBRIMER) to a focused laser beam after a one-step spin coating process on a buffer layer. The silicon oxide was used as a buffer layer. The refractive index of the HYBRIMER film is increased by exposure from a laser beam. Therefore, the refractive index of the exposed region is higher than that of the unexposed region, which forms the index modulation type waveguide without an etching process. The fabricated waveguide channels were baked at 120°C during 3hrs for stabilization of the organic and inorganic networks. The laser direct writing apparatus was used to produce the pattern of waveguide channels. This system consists of a He-Cd laser radiating 325nm beam, high-resolution computer-controlled translation stages and a video camera that images the sample onto a monitor. The pattern of the waveguide channel was written using various writing speeds to optimize the writing condition. The core section of optimized waveguides was a rectangular shape and the core dimension was 7μm wide and 8μm high. The refractive index is increased from 1.495 to 1.5 after exposure. The difference of the refractive index between the core and cladding was approximately 0.33%. The insertion loss of the waveguides was measured by cut-back method using a single-mode fiber as an input tip, a multimode fiber (50 μm GI) as an output tip, and a 1310nm wavelength laser light source. The insertion loss shows a linear relationship with the length of the waveguide. The propagation loss of the buried waveguide was approximately 0.3dB/cm at a wavelength of 1310nm.
The system performance of data- and telecommunication equipment must keep up with the increasing network speed. Optical interconnections technology is a promising alternative for high-throughput systems. We demonstrate the optical backplane system using a waveguide-embedded optical backplane and two processing boards. The transmitter and receiver modules were prepared for optical printed circuit boards (PCBs), which consists of the metal optical bench, the driver chips, vertical-cavity surface-emitting lasers (VCSELs), photodiodes, and a tapered polymeric waveguide. We report high-speed transmission of 27–1 pseudorandom bit sequence (PRBS) nonreturn to zero (NRZ) data up to 10 Gbits/s through the optical backplane system. The results demonstrate that the optical backplane system can be practical and valuable for the future high-throughput systems by using metal optical bench and precisely machined optical plug-adaptor structure to achieve stable board-to-board interconnection.
The performance of data and telecommunication equipment must keep up with the increasing network speed. Optical interconnection technology is a promising alternative for high throughput systems. The Optical backplane system was demonstrated with waveguide-embedded optical backplane, transmitter board and receiver board. The transmitter and receiver module were prepared for optical PCB, which consists of the metal optical bench, the driver chips, VCSELs, photodiodes and a tapered polymeric waveguide. And parallel optical transmitter and a receiver module were attached onto the processing boards for the interconnection with optical backplane board. The tapered polymeric waveguides are fabricated using the hot embossing technique. And the propagation loss of the waveguide was approximately 0.1dB/cm at 850nm. The waveguide-embedded optical backplane boards were fabricated by using conventional PCB lamination process. The data transmission characteristics of the processing board have been investigated. In our optical backplane system, we demonstrated up to 10Gb/s 2<sup>7</sup>-1 PRBS NRZ data transmission from the transmitter board to the receiver board through optical backplane. The BERs were less than 10<sup>-12</sup> under 8Gb/s data rate, which is sufficient level for telecommunications.
A fully optical PCB with transmitter/receiver system boards and optical bakcplane was prepared, which is board-to-board interconnection by an optical slot. We report a 10 Gb/s PRBS NRZ data transmission between transmitter system board and optical backplane embedded multimode polymeric waveguide arrays. The basic concept of the optical PCB is as follows; 1) Metal optical bench is integrated with optoelectronic devices, driver and receiver circuits, polymeric waveguide and access line PCB module. 2) Multimode polymeric waveguide inside an optical backplane, which is embedded into PCB, 3) Optical slot and plug for high-density (channel pitch : 500 um) board-to-board interconnection. The polymeric waveguide technology can be used for transmission of data between transmitter/receiver processing boards and backplane boards. The main components are low-loss tapered polymeric waveguides and a novel optical plug and slot for board-to-board interconnections, respectively. The transmitter/receiver processing boards are designed as plug types, and can be easily plugged-in and -out at an optical backplane board. The optical backplane boards are prepared by employing the lamination processes for conventional electrical PCBs. A practical optical backplane system was implemented with two processing boards and an optical backplane. As connection components between the transmitter/receiver processing boards and backplane board, optical slots made of a 90°-bending structure-embedded optical plug was used. A 10 Gb/s data link was successfully demonstrated. The bit error rate (BER) was determined and
is 5.6×10<sup>-9</sup>(@10Gb/s) and the BER of 8 Gb/s is < 10<sup>-12</sup>.
Polymer waveguides have attracted a great deal of attention for their potential applications as optical components in optical communications, optical interconnections and optical sensors because they are easy to manufacture at a low temperature, and they have a low processing cost. Hot embossing is powerful and effective tools to produce a large volume of waveguides and structure high-precision micro/nano patterns of thin polymer films using a stamp for optical applications. In this work, fabrication techniques of hot embossed polymeric optical waveguides for parallel optical interconnection module, multi-channel variable optical attenuator and optical printed circuit boards are demonstrated. The single- and multi-mode waveguides are produced by core filling and UV curing processes. New approaches to fabricating single-mode polymeric waveguides with the high thermal stability in thermosetting polymers and two-dimensional multi-mode polymeric waveguides for high-density parallel optical interconnections as well as a simultaneous fabrication of single-mode polymeric waveguides with micro pedestals for passive fiber alignment are also reported.
A novel optical PCB with transmitter/receiver system boards and optical bakcplane was prepared, which is board-to-board interconnection by optical plug and slot. We report an 8Gb/s PRBS NRZ data transmission between transmitter system board and optical backplane embedded multimode polymeric waveguide arrays. The basic concept of ETRI's optical PCB is as follows; 1) Metal optical bench is integrated with optoelectronic devices, driver and receiver circuits, polymeric waveguide and access line PCB module. 2) Multimode polymeric waveguide inside an optical backplane, which is embedded into PCB. 3) Optical slot and plug for high-density(channel pitch : 500um) board-to-board interconnection. The polymeric waveguide technology can be used for transmission of data on transmitter/ receiver system boards and for backplane interconnections. The main components are low-loss tapered polymeric waveguides and a novel optical plug and slot for board-to-board interconnections, respectively. The optical PCB is characteristic of low coupling loss, easy insertion/extraction of the boards and, especially, reliable optical coupling unaffected from external environment after board insertion.
A practical optical printed circuit board (PCB) was demonstrated, using a waveguide-embedded optical backplane and processing boards. The polymeric waveguide was produced by means of a hot embossing technique then embedded following a conventional lamination processes. The core size of waveguide was 100 x 60 μm<sup>2</sup> (input section), 60 x 60 μm<sup>2</sup> (output section), and the propagation loss of tapered polymeric waveguide was approximately 0.1 dB/cm at 850 nm. We prepared a optical backplane with polymeric waveguide by using conventional multilayer board lamination processes. The transmission power and dimension of the optical backplane was same as those of waveguide before lamination. A metal optical bench was used as a packaging die for the optical devices and the integrated circuit chips in both the transmitter and the receiver processing boards. We used a 1×4 850 nm VCSEL array with 2 dBm of output power for the transmitter and a PIN photodiode array for the receiver. We successfully demonstrated 8 Gb/s of data transmission between the transmitter processing board and the optical backplane board.