Pei-Hao Tseng

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.

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.

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.

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.

A 40-Gb/s Optical Module Using 4-Channel WDM TOSA for Access Network Applications

A 40-Gb/s optical module using WDM TOSAs for access network applications has been fabricated and demonstrated. This compact optical module was integrated by three thin-film WDM filters and four uncooled LX4 wavelength compatible DFB laser diodes. The output optical power was measured above -6 dBm with a clear 10-Gb/s transmission eye diagram. Due to the low dispersion characteristic of conventional single mode fiber at the LX4 wavelength, this module was expected to be able to transmit the signal up to 10 km and served as a cost-effective solution for 40-Gb/s transmission.

A 25-GHz TO-Can header for coaxial laser package on transmission applications

A new 5-pin transistor outline (TO-Can) header for conventional coaxial laser package has been proposed and demonstrated by using a three-dimensional full-wave electromagnetic simulation tool. The applicability of the simulation tool was verified by a measurement result of a conventional TO-56 header. By adopting a two-session feed-through via and a bent feed-lead, this TO-Can header has the optimal impedance for high-speed modulation. The reflection loss can be controlled beneath -10-dB before 15-GHz with a 50-Ω termination. The 3-dB modulated bandwidth with a load impedance of 5-Ω and 50-Ω is over 23-GHz and 37-GHz, respectively. This TO-Can header provides a low-cost coaxial laser package solution with widely load impedances from 5-Ω to 50-Ω and may apply in the emerging 100-Gigabits Ethernet (100GbE) and next generation Fiber Channel (20GFC) applications.

A 40Gb/s bidirectional CWDM-PON system for metro/access applications

A high capacity CWDM-PON system has been proposed and demonstrated experimentally. 8 wavelengths have been transmitted at a 10 km single-mode fiber successfully. This system enables the maximum subscribing bit-rate to 10 Gb/s for a client.

Electrical characterization of a 25 Gbit/s VCSEL module with TO-46 form factor packaging

A cost-effective differential-mode packaging of the TO-46 VCSEL module is proposed. The optimal bonding-wire and package solution have been demonstrated through frequency-domain and time-domain simulations. The differential-mode modulation bandwidth of the VCSEL module of above 21 GHz is achieved and a clearly opening eye diagram of 25 Gbit/s is observed. The electrical characterization of the VCSEL module under different driven source impedances is simulated and discussed.

A bidirectional CWDM-PON system with capacity of 40-Gb/s for metro/access applications

Using distributed feedback laser diode (DFB-LD) in a high-speed transmission system, the chirp effect in the LD is a factor limiting transmission span length. We discussed the impact of fiber chromatic dispersion on this system performance at 10-Gb/s due to LD chirp effect. For the dispersion range of −3.51 to 2.97 ps/nm·km, negative power penalties have been observed due to the pulse compression effect, which is resulted from a low chirp of DFB-LDs. We evaluated 10-Gb/s directly modulated DFB-LDs wavelengths from 1275-nm to 1350-nm of power penalties versus transmissible standard single-mode fiber (SMF) distance. The calculated power penalties are less than 1 dB for 20-km SMF transmission. Furthermore, we also achieve a bidirectional CWDM-PON system covering a wide wavelength of 1.3-µm and 1.5-µm with an aggregated data rate of 40-Gb/s is proposed and experimented. Four uncooled direct-modulated DFB-LDs with wavelengths of 1275-nm, 1300-nm, 1325-nm, and 1350-nm are adopted for the upstream transmission to lower the installation cost and dispersion effect. Another four external-modulated lasers by LiNbO3 modulators with wavelengths of 1510-nm, 1530-nm, 1550-nm, and 1570-nm are deployed for the downstream transmission to minimize the chirp effect. These lasers are operated at 10-Gb/s simultaneously for transmission over 10-km SMF. Downstream and upstream data of high capacity are operated at 10-Gb/s per channel simultaneously. This CWDM-PON network enables clients maximum subscribing bit rate to 10-Gb/s and the splitting ratio can vary from 1:4 to 1:64.