Takahashi Hiroshi

We applied a super-multi-fiber PLC connector for connecting up to 64 ch to the board packaging of an 8 × 8 delivery and coupling switch (DC-SW) module with a fiber sheet. The DC-SW module is composed of plural PLCs and needs a large amount of fiber crossing. The PLC connector can attach fibers to and remove them from a PLC endface and realizes a PLC receptacle module instead of a PLC pigtail module. The fiber sheet resolves the problem of fiber congestion. We demonstrate the smart optical fiber wiring and board packaging of a DC-SW whose optical performance matches that of a conventional switch in which the pigtail fibers of the PLC modules are fusion spliced and squeezed into a package.

In this paper, we report a wavelength-selective switch which consists of AWGs and an optical 1 x N spatial switch based on transversal filter configuration. The transversal type switch is advantageous, when we integrate thermally sensitive components such as AWGs or LDs with it, because the switch always consumes constant power, regardless of the output selection. We fabricated a wavelength-selective optical 1 x 4 spatial switch with 5 channel AWGs, and confirmed its operating principle. Also, we obtained extinction ratio of 20 dB. We believe that this kind of wavelength-selective switch is applied to wavelength router or optical cross connect system.

Optical circuits composed of delay lines and couplers are widely used in optical signal processing. However, optical component that employs such a circuit is not suitable in a system whose channel arrangement is periodic with respect to wavelength, since the transmission spectra of the circuit are theoretically periodic with respect to frequency. In this paper, we show that optical circuits with a uniform wavelength period can be realized by generating a wavelength dependent phase with the phase-generating coupler (PGC) that we propose. We have applied our method to a Mach-Zehnder interferometer (MZI) as an example of an optical circuit and obtained excellent transmission spectra with a uniform wavelength period.

Optical switches based on silica-based planar lightwave circuit (PLC) technology are promising devices for use in constructing optical switching systems because they have the advantages of a low insertion loss, high integration and high reliability. We have successfully fabricated a 32-channel 2×2 optical PLC switch array that is suitable for OADM systems. This switch was realized by using a new circuit configuration for OADM systems and a low power consumption technique to provide higher integration. We report the circuit configuration and good optical performance of this switch.

Optical switches based on silica-based planar lightwave circuit (PLC) technology are promising devices for use in constructing optical switching systems because they have the advantages of a low insertion loss, high integration and high reliability. We have successfully fabricated a 32-channel 2×2 optical PLC switch array that is suitable for OADM systems. This switch was realized by using a new circuit configuration for OADM systems and a low power consumption technique to provide higher integration. We report the circuit configuration and good optical performance of this switch.

We investigated two types of novel sliess controlling waveguide structure with a view lo realizing a polarization-insensitive silica-based AWG. We clarified the relationship between the polarization sensitivity and waveguide structure by using stress analysis. We experimentally confirmed that both waveguide structures successfully provide polarization-insensitive characteristics (AX<0.01 nm) without any optical degradation.

Optical switches based on silica glass waveguide planar lightwave circuit are promising devices for constructing a large-scale optical switching system because a lot of switch elements can be integrated and they have high reliability. This report describes the structure of the switch element, the design of whole switch circuit and new methods for improving their optical characteristics. Experimental results of 16 x 16 matrix switch, 1 x 128 selection switch, 8-array 1 x 8 switch and 8 x 8 DC switch are shown as application examples of this technology.

The planar lightwave circuit type optical switch (PLC-SW) is highly reliable and suitable for functionality integration. We have applied the PLC-SW to the lambda label routing unit or optical path cross-connect (OPXC) of a photonic multi-protocol label switching router that we have been developing since 2000. We developed a compact optical switch package in the OPXC with high-density PLC-SW devices implemented with high functionality. In this report, we briefly describe the OPXC, which is now a mature system. We then describe the optical switch package, its characteristics, and related reliability test results.

Optical cross-connects and optical add-drop multiplexers are essential for the construction of WDM network system with larger capacity and higher performance. Optical switches attract much attention because they will act as key devices in the network. Silica-based PLC optical switches we have developed have excellent optical characteristics and are near practical use. Among those optical switches, 8-arrayed 2x2 and 8-arrayed 1x2 optical switches was investigated in terms of reliability. Through a set of reliability tests based on Telcordia standards, we confirmed the sufficient mechanical strength and the long-term reliability of the switches.

We have developed planar lightwave circuit type switches (PLC-SWs) that offer the advantages of a low insertion loss and long-term stability, and which are useful for photonic network systems based on WDM technologies such as optical cross connect systems. This switch consists of a Mach-Zehnder interferometer and thin film heaters, and operates via the thermo-optic effect. Advances in WDM photonic networks have led to a need for more data channels. We have to develop a compact and large-scale optical switch and realize low power consumption. This paper describes a compact and low driving power PLC-SW that employs super high delta waveguides and heat insulating grooves. We have realized a very compact switch element that is l/3 smaller than a conventional element, and which uses 1/10 the driving power. We also report the applications of these configurations to IxN type switches, which are very useful for practical systems.

By optimizing the structure of the Mach-Zehnder interferometer made of silica-based waveguide and the lightwave circuit, it is shown that it is possible to obtain an optical switch with high extinction even if there is process variation in waveguide optical length and coupling ratio of directional coupler. We designed and fabricated 8-array 1 × 8 switch chips with this optimization and the chips exhibited average extinction of 56 dB without optical length adjustment after fabrication. It is also shown that the characteristics of the switch maintain in wide environmental temperature range with theoretical consideration on temperature dependence.