Glass dual-mode laser for radio-frequency carrier generation

Recently, dual mode lasers proved to be interesting sources for radio frequency generation at millimeter wave frequency and beyond, to be used in photonic RoF systems. As the optical modes can eventually be correlated, such sources associate the simplicity of heterodyning technique with the frequency stability. Still, most architectures require active frequency control loop to reach communication requirements to limit frequency drift, and reduce the phase noise of the generated carrier. In this communication, we propose the use of a free running dual mode laser integrated on glass for radio frequency generation. The device is fabricated on an ion-exchanged co-doped Erbium Ytterbium substrate to emit in the C-band. We demonstrate that this device is able to generate an ultra-narrow spectrum radio-frequency carrier, reaching 600Hz spectral linewidth without control loop nor thermal stabilization. As a proof of concept, the device proposed in this work produces a radio frequency at 6.1 GHz which has been evaluated as an electrical carrier in radio transmission experiments. Data rates of several Gbps using complex modulation formats such from BPSK to 64QAM have been successfully tested. The results are compliant with communications standards requirements, validating the use of such a source in Radio over Fibre (RoF) systems. This paper first presents the glass dual-mode laser design, followed by the characterization of the generated carrier to finally present the radio over fiber results.