Tuneable Microwave Photonics Filter based on Stimulated Brillouin Scattering with Enhanced Gain and Bandwidth Control

A Tuneable Microwave Photonics Gain Filter (TMWPF) is proposed based on Stimulated Brillouin Scattering (SBS). The TMWPF configuration exhibits a gain of ≃70dBm and tuneable bandwidth control which makes it attractive for applications requiring high gain and bandwidth variations with high precision. The proposed TMWPF configuration employs a tuneable laser, an Erbium-Doped Fibre Amplifiers (EDFA), Radio Frequency (RF) mixers, an RF Amplifier (RFA), Single Mode Fibre (SMF) and Gallium Arsenide (GaAs) I-Q Dual parallel Mach-Zehnder Modulator (DPMZM). The modulation scheme performed by I-Q DPMZM is controlled by a voltage bias controller. The performance of the filter is compared whilst using LiNbO3 Phase Modulators (PMs) and Intensity Modulators (IMs) instead of GaAs I-Q DPMZM. The TMWPF delivers 44dBm, 57dBm & 44dBm of gain for I-Q DPMZM, PM, and IM, respectively. The use of RFA resulted in a total gain of 62dBm, 69dBm & 52dBm for I-Q DPMZM, PM and Amplitude Modulators (AM), respectively. This configuration exhibits high Q, tuneable bandwidth by employing stokes SBS gain, RF mixer and RFA. The bandwidth of the filter is varied from 20MHz to 40MHz. The operation principle of the TMWPF is based on SBS stokes gain. By controlling the bias point of the I-Q DPMZM, the operating point can be varied between PM and IM allowing 6dBm gain control and the choice of PM or IM for specific applications. This gives improved filter performance. The full control of TMWFP’s gain is obtained by using EDFA. The EDFA controls the power of the tuneable laser pump. The control challenges of the proposed TMWPF along with improvement enhancements are reported. The proposed TMWPF exhibits tuneability of 32GHz in RF domain, and 40GHz in optical domain. To the best of our knowledge, this TMWPF exhibits the highest reported gain.