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Shimada Y.,Sumitomo Electric | Inoue S.,Sumitomo Electric | Anzai S.,Sumitomo Electric | Kawamura H.,Transmission Devices RandD Laboratories | And 2 more authors.
SEI Technical Review | Year: 2013

We have developed an SFP+ (Enhanced Small Form Factor Pluggable) optical transceiver module for 11.1 Gbit/ DWDM (dense wavelength division multiplexing) application, which can cover up to 100 km reach over standard singlemode fiber. We have also successfully reduced its total power dissipation to less than 1.5 W by utilizing a newly developed laser diode chip. This world's smallest and power-saving DWDM SFP+ optical transceiver will contribute to the downsizing of high density optical transmission equipment.

Ishikawa T.,Transmission Devices RandD Laboratories | Tanaka H.,Sumitomo Electric | Shibata M.,Sumitomo Electric | Tajima M.,Georgia Institute of Technology | And 2 more authors.
SEI Technical Review | Year: 2013

Full-band wavelength tunable lasers with high optical output power and narrow spectral linewidth have been required for digital coherent communication systems. Sumitomo Electric Industries, Ltd. manufactures integrable tunable laser assemblies (ITLAs) using chirped-sampled-grating distributed-reflector laser diodes (CSG-DR-LDs) as full-band wavelength tunable laser suitable for high optical output power operation. The authors optimized multi quantum well (MQW) active layers in the CSG-DR-LD, and achieved high optical output power of over +16dBm and narrow spectral linewidth below 200 kHz. These characteristics make the lasers promising for 100 Gbit/s digital coherent communication systems.

Inoue K.,Transmission Devices RandD Laboratories | Sano S.,Transmission Devices RandD Laboratories | Tateno Y.,Transmission Devices RandD Laboratories | Yamaki F.,Transmission Devices RandD Laboratories | And 4 more authors.
SEI Technical Review | Year: 2010

High power and high efficiency devices are increasingly required for the 3rd generation and other future base station transmitter systems (BTSs). Gallium nitride (GaN) is ideal for these applications because of its wide band gap and high saturated electron velocity. We have developed the GaN high electron mobility transistor (HEMT) grown on the silicon carbide (SiC) substrate and released the world's first commercial GaN HEMT products. We have also studied efficiency enhancement of the modern BTS amplifiers using Doherty and Class-E circuits. This paper summarizes the GaN HEMT development for the BTS amplifier applications and the efficiency enhancement techniques.

Ikagawa T.,Transmission Devices RandD Laboratories | Tanaka K.,Transmission Devices RandD Laboratories | Banno E.,Transmission Devices RandD Laboratories | Kaneko T.,Transmission Devices RandD Laboratories | Uesaka K.,Transmission Devices RandD Laboratories
SEI Technical Review | Year: 2013

The authors have successfully developed a tunable laser controller IC for digital coherent optical communication systems. The developed IC is composed of both analog and digital circuits fabricated by the CMOS (Complementary Metal Oxide Semiconductor) process, which contributes to the reduction of chip size and power dissipation. The IC, used in combination with an in-house tunable laser module, achieves even lower power dissipation by introducing switching regulators and can be implemented to small tunable assemblies, such as a micro-ITLA (Integrable Tunable Laser Assembly). This paper outlines the development of the tunable laser controller IC and its performance when used with an in-house tunable laser module.

Yanagisawa M.,Transmission Devices RandD Laboratories | Tsuji Y.,Transmission Devices RandD Laboratories | Yoshinaga H.,Transmission Devices RandD Laboratories | Kouno N.,Transmission Devices RandD Laboratories | Hiratsuka K.,Transmission Devices RandD Laboratories
SEI Technical Review | Year: 2010

The authors have succeeded in employing nanoimprint lithography (NIL) to form diffraction gratings of distributed feedback laser diodes (DFB LDs), which are increasingly used in optical communication. Uniform gratings and phaseshifted gratings with a period of 232 nm were formed by reversal NIL in combination with the use of a step-and-repeat imprint tool. Line edge roughness has been kept sufficiently low with the fabricated gratings. DFB LDs fabricated by NIL have indicated characteristics comparable to those of LDs fabricated by electron beam lithography, and have also shown high long-term stability in the threshold current. The authors have also demonstrated that phase-shifted DFB LDs show better uniformity in characteristics than uniformgrating LDs. The results of this study indicate that NIL has high potential for fabricating DFB LDs.

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