Direct optical injection locking of InP-based MODFET and GaAs-based HBT oscillators

We have investigated direct optical injection locking and tuning of high frequency oscillators made with GaAs/AlGaAs Heterojunction Bipolar Transistors (HBT´s) and 0.25 μm gate InGaAs/InAlAs Modulation Doped Field Effect Transistors (MODFET´s). We have developed an HBT technology using transparent indium-tin-oxide (ITO) emitter contacts for convenient optical access. Optical injection locking and tuning experiments have been performed on 6 GHz microwave oscillators made with the HBT´s. Locking ranges up to 2.5 MHz and tuning ranges up to 25 MHz have been measured with the injection of the optical RF power at 30 dB below the oscillator power level. Similarly, direct subharmonic optical injection locking at 10 and 19 GHz has been achieved with the MMIC InGaAs/InAlAs MODFET oscillators