This optical switch device is a compound semiconductor chip with a planer light wave circuit (PLC). The switch function is based on the carrier effect, which is the principle that the refractive index of a material decreases when current is injected. An electrode is installed in the cross area of the switch’s two waveguides. When current is applied to the electrode, a thin layer appears that has a lower refractive index than the surrounding region, causing an incoming beam of light to be reflected because of an optical phenomenon called total internal reflection. When the current is turned off, the beam passes through the cross area.

The use of compound semiconductors enables switching speeds under 2ns. This is the world’s fastest total-reflection-type optical switch device.

* according to our investigation as of February 2004.

Unlike an MZ interferometer, which uses the principle of interferometry, our switch design is based on the phenomenon of total internal reflection and its operation is wavelength independent.

We confirmed that the optical switch device has no wavelength dependency in the C band by conducting switching experiments in both edge wavelengths of the C band, i.e. 1565 nm and 1530 nm.

Experiments in other bands will be done in the future.

In a continuous switching test, observations were made of signals from two output ports of the optical switch device, whose 40G programmable pattern generator (PPG) generated an alternating pseudo packet sequence. The trigger output of the PPG was used as the switch control signal.

The frame length of the pseudo packet sequence was 3.2ns (16 bytes at 40Gbps) and the frame gap length was 2.4ns (12 bytes at 40Gbps). The frame gap was set to the same byte length used by Ethernet networks.

The very short frame length was selected to test high-speed switching. No signals were missed by the head and tail portions, indicating that the switching delay time was within acceptable limits and that the switch was working correctly.