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Inoue T.,FITEL Photonics Laboratory R and D Div | Kawashima H.,FITEL Photonics Laboratory R and D Div | Matsubara N.,FITEL Photonics Laboratory R and D Div | Nara K.,FITEL Photonics Laboratory R and D Div
Furukawa Review | Year: 2011

A silica-based planar lightwave circuit (PLC) that is required for a receiver frontend used in digital coherent telecommunication system is developed by integrating a polarization-beam splitter (PBS) and a 90-degree hybrid mixer. At first, by configuring a PBS for signal with a double-pass Mach-Zehnder interferometer, a PBS-integrated coherent mixer chip is developed and a polarization extinction ratio (PER) higher than 30 dB is achieved. In the next stage, downsizing of a PLC chip is studied. For this purpose, the relative refractive index difference ? is improved to 1.8%, and a circuit layout of folded waveguide is employed. As a result, an ultra-small PBS integrated mixer chip with dimension of 12 mm×12 mm is realized. Using the developed chips in digital coherent receivers, experiments to demodulate dualpolarization quadrature phase-shift keying (DP-QPSK) signals at 40 Gbit/s and 100 Gbit/s are conducted, and excellent performances were confirmed in both cases.

Ariga M.,FITEL Photonics Laboratory R and D Div | Sugaya T.,FITEL Photonics Laboratory R and D Div | Kimura T.,FITEL Photonics Laboratory R and D Div | Akizuki K.,FITEL Photonics Laboratory R and D Div | And 2 more authors.
Furukawa Review | Year: 2011

To get a high performance and a high reliability, we had improved the miniaturization of modules and components on the FBT laser module, and then bonding these components with resin adhesive becomes essential to allow flexibility of its design. However, with respect to the usage of organic resin in the sealed package, outgas deposition in the optical components becomes a concern. Then, conducting analytical experiments which applied in the cases of high temperature condition over long periods or checking the existence of uncured resin, we proved that the deposition does not influence the reliability and it becomes possible to use resin adhesive. According to this result, we have developed the FBT laser modules which use the resin adhesive to bond the components, and achieved the high performances such as lower power consumption of 24% and higher optical output power of 15%.

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