We report on an opto-electronic oscillator (OEO) widely tunable from 2.5 to 5.5 GHz. It is based on an Er,Yb:glass Dual-Frequency Laser operating at 1.53 which naturally provides an electrically-tunable beatnote. Inserted in an optical frequency-locked loop including a long fiber delay line, the laser beatnote reaches a spectral purity comparable to the one obtained with classical fixed frequency OEOs. As the oscillator scheme does not require an RF filter, the tunability is simply achieved by tuning the laser beatnote frequency. A fine optimization of the loop has allowed reaching a -27 dBc/Hz (respectively -108 dBc/Hz) phase noise power spectral density at 10 Hz (respectively 10 kHz) of the carrier with only 100 m optical fiber, this performance being independent of the frequency.Index Terms-Dual-frequency laser, optical frequency-locked loop (OFLL), opto-electronic oscillator.

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We present several laser sources dedicated to advanced microwave photonic applications. A quantum-dash mode-locked laser delivering a high-power, ultra-stable pulse train is first described. We measure a linewidth below 300 kHz at a 4.3 GHz repetition rate for an output power above 300 mW and a pulse duration of 1.1 ps after compression, making this source ideal for microwave signal sampling applications. A widely tunable (5-110 GHz), monolithic millimeter-wave transceiver based on the integration of two semiconductor distributed feedback lasers, four amplifiers, and two high-speed uni-traveling carrier photodiodes is then presented, together with its application to the wireless transmission of data at 200 Mb∕s. A frequency-agile laser source dedicated to microwave signal processing is then described. It delivers arbitrary frequency sweeps over 20 GHz with high precision and high speed (above 400 GHz∕ms). Finally, we report on a low-noise (below 1 kHz linewidth), solid-state, dual-frequency laser source. It allows independent tuning of the two frequencies in the perspective of the implementation of a tunable optoelectronic oscillator based on a high-Q optical resonator.

We present the full characterization of the beatnote of an erbium doped distributed feedback fiber laser (DFB-FL) operating on two orthogonally polarized eigenstates around 1.55 µm. The dual-frequency laser (DFL) in the free running regime generates a microwave signals around 1 GHz with a RIN lower than -115 dB/Hz over the range 50 kHz-10 MHz and a phase noise of -67 dBc/Hz at 10 kHz of the RF carrier. Up to 600 MHz tunability of the RF beatnote is obtained by mechanical stress applied to the cavity

The photodiode impact on the phase noise of an optical link, and particularly its ability to convert the laser amplitude noise into microwave phase noise, is studied and modeled. The model involves a nonlinear RC cell which describes a photogeneration delay which is a function of the optical power. The whole system is then implemented on a microwave CAD software, and the link gain and phase noise performance are computed.