<10Hz linewidth optical millimetre-wave source for fibre-radio systems using a dual mode dfb semiconductor laser

We demonstrate the generation of millimetre-wave signals with <10Hz linewidth and with 500MHz locking range using a dual mode semiconductor laser. A subharmonic drive signal phase locks the beat signal produced by heterodyning the two modes. Recently frequencies in the millimetre-wave band have been proposed to meet the future demand for broadband wireless access networks. Frequencies at 62-63GHz and 65-66GHz have been allocated in Europe for the Mobile Broadband System (MBS) and the 40GHz region has been identified for longer range (up to 1km) applications such as video distribution. To enable this technology with low cost, fibre distribution of radio signals at 40GHz and 60-70GHz will be required. Very few optical sources cap of modulation at these frequencies have been demonstrated [1,2].