Tien-Tsorng Shih

New all-optical logic gates based on the local nonlinear Mach-Zehnder interferometer

We propose new all-optical logic gates containing a local nonlinear Mach-Zehnder interferometer waveguide structure. The light-induced index changes in the Mach-Zehnder waveguide structure make the output signal beam propagate through different nonlinear output waveguides. Based on the output signal beam propagating property, various all-optical logic gates by using the local nonlinear Mach-Zehnder waveguide interferometer structure with two straight control waveguides have been proposed to perform XOR/NXOR, AND/NAND, and OR/NOR logic functions.

High-Performance Low-Cost 10-Gb/s Coaxial DFB Laser Module Packaging by Conventional TO-Can Materials and Processes

High-performance low-cost 10-Gb/s coaxial DFB laser module packages made by conventional TO-Can materials and processes are developed and fabricated. The laser module has a built-in matching resistor to reduce the resonant phenomenon. In order to optimize the modules performance, a detailed equivalent circuit model is established to investigate both the DFB laser diode and the coaxial package comprehensively. This uncooled 10-Gb/s laser module operates at a high temperature of up to 105degC, and maintains an eye mask margin above 28% in the full operational temperature range to meet the stringent requirements of 10-Gb/s Ethernet for long-reach applications. This paper demonstrates that it is possible to fabricate cost-effective packages using existing low-cost TO-Can package technology while maintaining the high performance of the 10-Gb/s coaxial laser modules. Previously, the high-performance 10-Gb/s coaxial laser modules have only been available by using complicated design, customized components, and specialized fabrication process

High-Performance and Low-Cost 10-Gb/s Bidirectional Optical Subassembly Modules

High-performance and low-cost 10-Gb/s bidirectional optical subassembly (BOSA) modules that are obtained by adopting low-cost transistor outline (TO)-Can materials and processes are proposed and demonstrated. The BOSA module consists of an uncooled 1.3-mum distributed-feedback laser diode and a 1.5-mum p-i-n/transimpedance amplifier receiver (Rx), which integrate a 45deg tilted thin-film wavelength-division multiplexing filter to transmit a 1.3-mum light into the fiber and reflect a 1.55-mum light into the Rx. The matching resistor and low parasitic inductance packages are applied with the TO-Can laser diode to enable 10-Gb/s operation. A modulation bandwidth of 11.86 GHz and an OC-192 eye diagram of a 19% mask margin are obtained from the transmitter side. After a 10-km single-mode fiber (SMF) transmission, the mask margin for the OC-192 eye diagram decreases to 11%. For the Rx, an OC-192 eye diagram of a 31% mask margin is obtained under back-to-back connections. The mask margin is maintained at 29% after a 10-km SMF transmission. The measured crosstalk penalty is 0.9 d 15 at the Rx side. These results indicate that the BOSA module is capable of a 10-Gb/s bidirectional transmission. This unique high-performance 10-Gb/s BOSA module not only demonstrates the feasibility of a 10-Gb/s bidirectional transmission on an SMF for fiber-to-the-home applications but also shows the low-cost possibility to ensure the success of next-generation 10-Gb/s access networks.

Fabrication and Characteristics of Ce-Doped Fiber for High-Resolution OCT Source

The fabrication of Ce-doped fibers (CeDFs) is demonstrated by drawing-tower method employing rod-in-tube technique. The fluorescence spectrum of CeDFs with a 16-μm core exhibited a 160-nm broadband emission with 1.45-μm axial resolution. This CeDF may be functioned as a high-resolution light source for optical coherence tomography applications.

Compact TO-CAN Header With Bandwidth Excess 40 GHz

A large bandwidth transistor outline (TO)-CAN header used in a low cost laser module was designed through a three dimensional full wave electromagnetic simulation and demonstrated by a direct measurement technique. The simulation results show that the proposed TO-CAN header provides a resonance-free transmission bandwidth in excess of 40 GHz with a reflection loss of 25 GHz under -10 dB with an ideal 50 Ω terminal. A pair of specially designed K type adaptors was used to accommodate the TO-CAN header for the high frequency measurements. This is a direct contact setup, without extra parasitic effects, and allowing a near resonance-free measurement. The experimental results are in good agreement with simulated results in the frequency range up to 40 GHz. A time-domain reflectometry measurement and a 40 Gbit/s eye diagram test were made to verify the performance. In addition, a laser module packaged with the TO-CAN header is proposed. By taking the bonding wires into account, the simulated transmission bandwidth of the module is over 35 GHz and a clear 25 Gbit/s eye diagram is obtained. This cost effective package solution of laser module can be applied in the next generation 100 Gigabit Ethernet (100 GbE) network.

A 25 Gbit/s Transmitter Optical Sub-Assembly Package Employing Cost-Effective TO-CAN Materials and Processes

A cost-effective 25 Gbit/s directly modulated transmitter optical sub-assembly (TOSA) employing transistor outline (TO)-CAN materials and processes is demonstrated. A high speed distributed feedback laser diode (DFB LD) chip used in the TOSA is characterized by a directly high frequency probing measurement and an equivalent circuit model according to the measurement result. Using a TOSA package with TO-CAN structure and applying the deduced equivalent circuit model of the DFB LD chip in the simulation, a modified TOSA is proposed. The parasitic effect of bonding-wire and the gap induced in die bonding process is studied comprehensively to achieve an optimum configuration. Based on the simulated result, the proposed TOSA is fabricated through a conventional TO-CAN and TOSA fabrication process. The measured results show that the TOSA exhibits a 3-dB bandwidth of 18.7 GHz and a clearly opening eye diagram of 25 Gbit/s. This developed TOSA is potential for use in the next generation fiber network of 25 Gbit/s or 100 Gbit/s due to advantages of cost-effective design and mass production capability.

High-performance and low-cost 10Gbps coaxial DFB laser module packaging by conventional TO-Can materials and processes

The high-performance and low-cost 10Gbps coaxial DFB laser module packaging by conventional TO-Can materials and processes are developed and fabricated. The laser module has a built-in matching resistor to reduce the resonant phenomenon. In order to optimize the modules performance, detailed equivalent circuit model is established to investigate both the DFB laser diode and the coaxial package comprehensively. After a proper design and fabrication, this uncooled 10Gbps laser module could operate at a high temperature up to 105degC and maintain an eye mask margin above 28% in the full operational temperature range to meet the stringent requirements of 10Gbps Ethernet for long reach applications. Previously, the high-performance 10Gbps coaxial laser modules have only been available by using complicated design, customized components, and specialized fabrication process

Low-Cost TO-Can Header for Coaxial Laser Modules in 25-Gbit/s Transmission Applications

A new transistor outline-Can (TO-Can) header for a low-cost coaxial laser module for 25-Gbit/s transmission is proposed and demonstrated using a 3-D full-wave electromagnetic simulation. The simulation result is compared with the measured results of a conventional TO-56 header to verify its applicability. A two-section feedthrough hole is employed, and a wire-over-ground feed lead is introduced to overcome the impedance matching problems. The simulation results show that the proposed TO-Can header provides a transmission bandwidth in excess of 40 GHz and reflection loss less than -10 dB below 26 GHz, with an ideal 50-Ω terminal. Taking the bonding wires into account, the transmission bandwidth still reaches 28 GHz. The electrical characteristics of this TO-Can package were extracted and combined with a small-signal equivalent circuit model of a 24.5-GHz laser diode to simulate the electrical characteristics of a full coaxial laser module. The 3-dB bandwidth is 20.5 GHz, which allows the laser module to operate at 25 Gbit/s. This superior TO-Can header provides a low-cost coaxial laser package solution and can be applied in the emerging 21-Gbit/s fiber channel (20 GFC) and 100-gigabit (4 × 25 Gbit/s) Ethernet (100 GbE) networks.

Comparison of single-/few-/multi-mode 850 nm VCSELs for optical OFDM transmission

For high-speed optical OFDM transmission applications, a comprehensive comparison of the homemade multi-/few-/single-transverse mode (MM/FM/SM) vertical cavity surface emitting laser (VCSEL) chips is performed. With microwave probe, the direct encoding of pre-leveled 16-QAM OFDM data and transmission over 100-m-long OM4 multi-mode-fiber (MMF) are demonstrated for intra-datacenter applications. The MM VCSEL chip with the largest emission aperture of 11 μm reveals the highest differential quantum efficiency which provides the highest optical power of 8.67 mW but exhibits the lowest encodable bandwidth of 21 GHz. In contrast, the SM VCSEL chip fabricated with the smallest emission aperture of only 3 μm provides the highest 3-dB encoding bandwidth up to 23 GHz at a cost of slight heat accumulation. After optimization, with the trade-off set between the receiving signal-to-noise ratio (SNR) and bandwidth, the FM VCSEL chip guarantees the highest optical OFDM transmission bit rate of 96 Gbit/s under back-to-back case with its strongest throughput. Among three VCSEL chips, the SM VCSEL chip with nearly modal-dispersion free feature is treated as the best candidate for carrying the pre-leveled 16-QAM OFDM data over 100-m OM4-MMF with same material structure but exhibits different oxide-layer confined gain cross-sections with one another at 80-Gbit/s with the smallest receiving power penalty of 1.77 dB.

High-Performance and Low-Cost 40-Gb/s CWDM Optical Modules

High-performance and low-cost 40-Gb/s optical modules using four different wavelength uncooled 10-Gb/s distributed-feedback (DFB) lasers are proposed and demonstrated. The 40-Gb/s optical module was integrated with coarse wavelength division multiplexing (CWDM) thin-film filters which enabled four 10-Gb/s transmission channels output through a single fiber. The 10-Gb/s DFB laser was packaged by commercialized low-cost coaxial TO-Can technology. The results of the 40-Gb/s optical module showed that the output optical power was above -1 dBm per channel and the system power budget was 12 dB. The transmission distance with a single-mode fiber reached more than 30 km at a bit-error-rate of 10-9. Compared with conventional 40-Gb/s optical modules, the module is easy to fabricate and is low cost. This proposed high-performance 40-Gb/s CWDM optical module demonstrates not only the feasibility of a 30 km transmission, but also shows the low-cost possibility of ensuring the application of WDM-passive optical network fiber-to-the-home systems.