Switchable transceiver module

In telecommunications, optical transmission paths are increasingly being used to transmit data with the aid of modulated light signals. Here, laser light is converted into an optical signal with an external optical modulator and transmitted using wavelength division multiplex systems.

State of the art

In order to simultaneously enable transmitting and receiving, separate transmission and reception channels are currently needed whose function has been pre-set. As a result, a larger number of wavelength channels is required. Mutual transmission in one channel is only possible with the aid of complex optical splitters or switches which, however, are rarely used in practice due to high costs.

Technology

At the KIT Institute for Data Processing and Electronics (IPE), scientists have developed a transceiver for wavelength division multiplex systems that enables switching from the transmitting to the receiving function in a single channel. The transceiver consists of components that are also used in the common Mach-Zehnder modulators: multimode interferometers (MMI), high-frequency modulators and a photodiode. The special feature are two outputs, one of which is connected to the photodiode. In the transmitting direction, uniform light is fed in, modulated and passed on as a signal. In contrast, in the receiving direction, modulated light is fed in, goes through the transceiver and transmits the signal at the photodiode, which in this case acts as a receiving diode in addition to monitoring proper. Log control allows for the respective mode to be regulated, whereby the modulator becomes a switch.

Advantages

The new transceiver achieves a greater functional scope and dual use without raising the complexity of the chip design. In addition, the transceiver is dynamically reconfigurable if transmission and reception capacities fluctuate. A single chip layout can be used for various purposes, which results in advantages for production.

Options for companies

The technology is particularly suitable for shorter transmission paths such as those in process data communication. KIT is looking for companies to develop and apply the switchable transceiver.