Advantest Laboratories and a group from the Japanese Tohoku University have jointly developed a laser device which is able to transmit large volumes of data using DWDM (Dense Wavelength Division Multiplexing) along optical fiber lines. In existing optical communications systems using WDM (Wavelength Division Multiplexing) the individual optical signals need to separated by at least 10GHz to prevent overlap of signals in the optical fiber as the signals do not have stable frequencies. However, the new laser device produces light with such a high-frequency stability that signals only need to be separated by at least 10MHz, resulting in the transmission of ten to 100 times as many signals.