Tae-Woo Lee

High-efficiency and stable optical transmitter using VCSEL-direct-bonded connector for optical interconnection

A high-efficiency optical transmitter module for PCB (printed circuit board)-based interconnections was fabricated using a bottom-emitting VCSEL. The bottom-emitting VCSEL was directly bonded by an epoxy on a 90 degrees -bent fiber connector which is inserted into the PCB to couple to the fiber layer embedded in the board. A ray trace simulation indicates that close contact between the VCSEL and the connector removes most of the losses due to Fresnel reflection and beam divergence. This tendency was experimentally identified. Thermal dissipation through the epoxy layer and the connector also improves significantly the power characteristics of the VCSEL. The VCSEL after bonding on the connector shows about 40% higher power compared to that of the bare VCSEL at the current showing a peak power before bonding. The results indicate that direct bonding improves both optical and electrical efficiencies. A successful eye diagram at the speed of 5 Gb/s/ch with 850 nm was accomplished from the VCSEL-direct-bonded transmitter module.

10 Gbps Transimpedance Amplifier-Receiver for Optical Interconnects

2with power consumption of 16.9 mW at 1.3 V. The measured input-referred noise of optical TIA-Rx is 20 pA/√Hz with a 3-dB bandwidth of 6.9 GHz. The proposed TIA-Rx achieved a high gain-bandwidth product per DC power figure of merit of 408 GHzΩ /mW.

40 Gb/s optical subassembly module for a multi-channel bidirectional optical link

A 40 Gb/s bidirectional optical link using four-channel optical subassembly (OSA) modules and two different wavelengths for the up- and down-link is demonstrated. Widely separated wavelengths of 850 nm and 1060 nm are used to reduce the optical crosstalk between the up- and down-link signals. Due to the integration capabilities of silicon, the OSA is implemented, all based on silicon: V-grooved silicon substrates to embed fibers and silicon optical benches (SiOBs) to mount optical components. The SiOBs are separately prepared for array chips of photodiodes (PDs), vertical-cavity surface-emitting lasers (VCSELs), and monitoring PDs, which are serially configured on an optical fiber array for direct coupling to the transmission fibers. The separation of the up- and down-link wavelengths is implemented using a wavelength-filtering 45° mirror which is formed in the fiber under the VCSEL. To guide the light signal to the PD another 45° mirror is formed at the end of the fiber. The fabricated bidirectional OSA module shows good performances with a clear eye-diagram and a BER of less than 10(-12) at a data rate of 10 Gb/s for each of the channels with input powers of -8 dBm and -6.5 dBm for the up-link and the down-link, respectively. The measured inter-channel crosstalk of the bidirectional 40 Gb/s optical link is about -22.6 dB, while the full-duplex operation mode demonstrates negligible crosstalk between the up- and down-link.

Performance Analysis of Vertical and Horizontal Transmitter Array Modules Using Short- and Long-Wavelength VCSELS for Optical Interconnects

For short- and long-wavelength vertical surface-emitting lasers (VCSELs), performances of optical transmitter array modules with vertically and horizontally packaged structures are analyzed for application to on-board optical interconnection. 850 and 1310 nm wavelengths are selected for the short- and long-wavelength light sources. For each wavelength, top- and bottom-emitting VCSELs are used to compare the performances of four different module structures: bottom-emitting types of 850 and 1310 nm for the vertical modules, and top-emitting types of 850 and 1310 nm for the horizontal modules. The horizontal transmitter modules are packaged using the conventional wire-bonding technology for the interconnect between VCSEL and driver chips while the vertical modules are packaged using the flip-chip-bonding technology. Signal crosstalk is investigated using 1<formula formulatype=inline><tex Notation=TeX>

Design of small-area transimpedance optical receiver module for optical interconnects

,times,

Bidirectional CMOS Transceiver With Automatic Mode Control for Chip-to-Chip Optical Interconnects

</tex></formula>4 VCSEL array chips, which are driven using the same Si-CMOS circuits designed for 5 Gb/s operation. The vertical modules show lower crosstalk than the horizontal modules. When the gap distance between the VCSEL aperture and the waveguide input port increases up to 500 <formula formulatype=inline><tex Notation=TeX>

Analytical model for crosstalk analysis of optoelectronic transmitter modules for optical interconnects

mu{rm m}

2.5-Gb/s/ch Long Wavelength Transmitter Modules for Chip-to-Chip Optical PCB Applications

</tex></formula> for each module, the crosstalk increases in a range <formula formulatype=inline><tex Notation=TeX>

Design of transimpedance amplifier for optical receivers in 0.13 µm CMOS

{-}{58}

Bidirectional optical transceiver integrated with an envelope detector for automatically controlling the direction of transmission

</tex></formula> to <formula formulatype=inline><tex Notation=TeX>