Fabrication of a low-cost module for Gigabit Ethernet transceivers (original) (raw)
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Fabrication of a low-cost module for gigabit ethernet transceivers
VCSELs and Optical Interconnects, 2003
In this paper, a novel way for the fabrication of opto-electronic transceiver modules is proposed. These modules are characterized by the use of MT-RJ connectors, low-cost fabrication tools, highly efficient opto-electronic components such as VCSELs and CMOS integrated detectors, and an easy fabrication scheme. The module is based on the direct alignment technique; this means that the fibre and the photo detector and laser diode are self and directly aligned with respect to each other, without the need for optical lenses. Cost are expected to be low, since the transceiver module can be fabricated using existing mass volume fabrication techniques
Self-Alignment of Optical Devices With Fiber for Low-Cost Optical Interconnect Modules
IEEE Photonics Technology Letters, 2000
We propose a novel self-alignment process of optical devices with optical fiber. A vertical-cavity surface-emitting laser (VCSEL) was automatically coupled with a multimode fiber (MMF) through the surface tension of a liquid adhesive within 1.5 s. Misalignment between the center of the VCSEL and the fiber was measured to be 15 m, which is acceptable for coupling the VCSEL with the MMF. High-speed pulse modulation of the self-aligned VCSEL up to 5 Gb/s, as well as at 1 Gb/s, was demonstrated. The average optical output power was as high as 05.9 dBm at 1 Gb/s.
Optics Express, 2009
Compact and passive-alignment 4-channel × 2.5-Gbps optical interconnect modules are developed based on the silicon optical benches (SiOBs) of 5 × 5 mm 2. A silicon-based 45° micro-reflector and V-groove arrays are fabricated on the SiOB using anisotropic wet etching. Moreover, high-frequency transmission lines of 4 channel × 2.5 Gbps, and bonding pads with Au/Sn eutectic solder are also deposited on the SiOB. The vertical-cavity surface-emitting laser (VCSEL) array and photo-detector (PD) array are flip-chip assembled on the intended positions. The multimode fiber (MMF) ribbons are passively aligned and mounted onto the Vgroove arrays. Without the assistance of additional optics, the coupling efficiencies of VCSEL-to-MMF in the transmitting part and MMF-to-PD in the receiving part can be as high as −5.65 and −1.98 dB, respectively, under an optical path of 180 µm. The 1-dB coupling tolerance of greater than ± 20 µm is achieved for both transmitting and receiving parts. Eye patterns of both parts are demonstrated using 15-bit PRBS at 2.5 Gbps.
Procedia Engineering, 2017
100 Gbps (4 × 25 Gbps) optical receiver (Rx) module is demonstrated using Germanium (Ge) photodetector (PD) which is fabricated through Silicon-photonics process using 750 ohm-cm of high-resistivity silicon oxide insulator (SOI) wafer. Transimpedance amplifier (TIA) and Ge PD are packaged with chip-on-board (COB) manner on a printed circuit board (PCB). High speed PCB for the assembly of both electronic and photonic devices in COB package is precisely designed from the material selection to the device footprint layout and transmission line design. The layout on PCB is optimized using high frequency simulation tool of HFSS to minimize RF loss happening in the transmission line and electrical interconnection points of bond wires. Electrical-optical (EO) S-parameter measurement for the Ge PD shows 22 GHz of transmittance (S21) 3dB bandwidth. Photocurrents of the photodetector induced by the optical input power are analyzed for signal integrity both TIA ON and OFF states. Photocurrent changes by the misalignment of the lensed optical fiber coupled to the edge coupler of the Ge PD shows that 3dB misalignment tolerances are 5.5 µm in the longitudinal and around +/-1 µm in the lateral directions. This COB packaging technique of optical Rx module can be applied for the integration and assembly of the optical module of higher data rate of 100 Gbps and beyond.
Development of Packaging Technologies for High-Speed ($≫40$Gb/s) Optical Modules
IEEE Journal of Selected Topics in Quantum Electronics, 2000
We developed high-speed optoelectronics packaging technologies for a waveguide photodiode and a traveling wave electro-absorption modulator device for 40-Gb/s digital communication systems. The effects of the device and the packaging designs on the broadband performance were investigated to optimize broadband characteristics. For the receiver, inductive peaking was used for bandwidth control and an internal bias tee was implemented; in addition, two types of preamplifier devices were used to develop high-gain receiver and wide-bandwidth receiver. In the optical-to-electrical response, a 3-dB bandwidth of the high-gain module was about 32 GHz as compared to 42 GHz for the widebandwidth module. The clear 40-Gb/s nonreturn-to-zero (NRZ) eye diagrams showed a good system applicability of these modules. In addition, an optimized modulator module showed a 3-dB bandwidth of 38 GHz in the electrical-to-optical response, an electrical return loss of less than 10 dB at up to 26 GHz, an rms jitter of 1.832 ps, and an extinction ratio of 5.38 dB in a 40-Gb/s NRZ eye diagram.
SPIE Proceedings, 2009
Multichip transmitter modules in which VCSEL chips were packaged on Si-CMOS driver IC chips have been investigated to apply in the optical interconnection using optical printed-circuit board. The modules were prepared using of 1 x 4 bottom-emitting VCSELs which were flip-chip-bonded on a driver IC fabricated by 0.18 μm Si-CMOS technology. Dynamic characteristics and optical crosstalk were compared for two types of VCSELs; 850 nm short-wavelength and 1310nm long-wavelength VCSELs. The two modules showed bit error rate less than 10-12 with clear eye openings at 2.5 Gbps. The 3-dB bandwidth was 3.2 GHz for the 850 nm module and 3.8 GHz for the 1310 nm module. When the VCSEL aperture was directly contacted with the input port of the fiber, the optical crosstalk within the 3-dB bandwidth showed-53.2 dB for 850 nm module and-57.2 dB for 1310 nm module. These low crosstalk values for both modules might be attributed to the flat surface of the bottom-emitting VCSEL devices allowing tight contact with the fiber surface. This low optical crosstalk performance is an additional advantage of the multichip module, adding to the general advantages in compact packaging and low electrical crosstalk.
IEEE Transactions on Advanced Packaging, 2005
Polylithic integration of electrical and optical interconnect technologies is presented as a solution for merging silicon CMOS and compound semiconductor optoelectronics. In contrast to monolithic and hybrid integration technologies, polylithic integration allows for the elimination of optoelectronic and integrated optic device-related processing from silicon CMOS manufacturing. Printed wiring board-level and compound semiconductor chip-level waveguides terminated with volume grating couplers facilitate bidirectional optical communication, where fiber-to-board and board-to-chip optical coupling occurs through a two-grating (or grating-to-grating) coupling path. A 27% increase in the electrical signal I/O projected by and 33% increase in the number of substrate-level electrical signal interconnect layers implied by the International Technology Roadmap for Semiconductors (ITRS) projections for the 32-nm technology generation are required to facilitate 10 Tb/s aggregate bidirectional fiber-to-the-chip communication. Buried air-gap channels provide for the routing of chip or board-level encapsulated air-clad waveguides for minimum crosstalk and maximum interconnect density. Optical signals routed on-board communicate with on-chip volume grating couplers embedded as part of a wafer-level batch package technology exhibiting compatible electrical and optical input/output interconnects. Measurements of grating-to-grating coupling reveal 31% coupling efficiency between two slab, nonoptimized, nonfocusing volume grating couplers.
Journal of Lightwave Technology, 2000
We propose a self-alignment process of an optical device with an optical multimode fiber (MMF) and a novel optical subassembly using a pre-self-aligned device. In order to form the pre-self-aligned device, the optical device such as a vertical-cavity surface-emitting laser (VCSEL) is aligned with the MMF using the surface tension of a transparent liquid adhesive. The optical subassembly we have developed is provided with a simple structure consisting of the pre-self-aligned VCSEL and an interposer board to be mounted on a printed circuit board (PCB). Details of the low-cost self-alignment technology and the optical subassembly are reported. Alignment accuracy of average 13 m is achieved and coupling efficiency of the self-aligned VCSEL to the MMF is determined to be maximum 35%. 1-Gb/s optical signal transmission using the optical subassembly is also demonstrated. This self-alignment technology and the fabricated optical subassembly are effective in achieving low-cost optical modules for optical interconnect systems from commodities to high-end applications.
Optics Express, 2011
Ribbon plastic optical fiber (POF) linked four-channel optical transmitter (Tx) and receiver (Rx) modules have been proposed and realized featuring an excellent alignment tolerance. The two modules share a common configuration involving an optical sub-assembly (OSA) with vertical cavity surface emitting lasers (VCSELs)/photodetectors (PDs), and their driver ICs, which are integrated onto a single printed circuit board (PCB) substrate. The OSA includes an alignment structure, a beam router and a fiber guide, which were produced by using plastic injection molding. We have accomplished a fully passive alignment between the VCSELs/PDs and the ribbon POF by taking advantage of the alignment structure that serves as a reference during the alignment of the constituent parts of the OSA. The electrical link, which largely determines the operation speed, has been remarkably shortened, due to a direct wire-bonding between the VCSELs/PDs and the driver circuits. The light sources and the detectors can be individually positioned, thereby overcoming the pitch limitations of the ribbon POF, which is made up of perfluorinated graded-index (GI) POF with a 62.5 μm core diameter. The overall alignment tolerance was first assessed by observing the optical coupling efficiency in terms of VCSEL/PD misalignment. The horizontal and vertical 3-dB alignment tolerances were about 20 μm and 150 μm for the Tx and 50 μm and over 200 μm for the Rx, respectively. The VCSEL-to-POF coupling loss for the Tx and the POF-to-PD loss for the Rx were 3.25 dB and 1.35 dB at a wavelength of 850 nm, respectively. Subsequently, a high-speed signal at 3.2 Gb/s was satisfactorily delivered via the Tx and Rx modules over a temperature range of 30 to 70°C with no significant errors; the channel crosstalk was below 30 dB. Finally, the performance of the prepared modules was verified by transmitting a 1080p HDMI video supplied by a Bluelay player to an LCD TV.
Low-Cost PCB-Integrated 10-Gb/s Optical Transceiver Built With a Novel Integration Method
— A novel integration method for the production of cost-effective optoelectronic printed circuit boards (OE PCBs) is presented. The proposed integration method allows fabrication of OE PCBs with manufacturing processes common to the electronics industry while enabling direct attachment of electronic components onto the board with solder reflow processes as well as board assembly with automated pick-and-place tools. The OE PCB design is based on the use of polymer multimode waveguides, end-fired optical coupling schemes, and simple electro-optic connectors, eliminating the need for additional optical components in the optical layer, such as micro-mirrors and micro-lenses. A proof-of-concept low-cost optical transceiver produced with the proposed integration method is presented. This transceiver is fabricated on a low-cost FR4 substrate, comprises a polymer Y-splitter together with the electronic circuitry of the transmitter and receiver modules and achieves error-free 10-Gb/s bidirectional data transmission. Theoretical studies on the optical coupling efficiencies and alignment tolerances achieved with the employed end-fired coupling schemes are presented while experimental results on the optical transmission characteristics, frequency response, and data transmission performance of the integrated optical links are reported. The demonstrated optoelec-tronic unit can be used as a front-end optical network unit in short-reach datacommunication links.