Tunable microwave photonic filter based on a fiber ring and erbium-doped fiber amplifier

Abstract

The tunable microwave photonic filter based on a fiber ring and erbium-doped fiber amplifier (EDFA) was proposed. By introducing a section of erbium-doped fiber (EDF) into the fiber ring, the loss of the signal can be compensated by the EDFA gain through adjusting the pump power. This can largely increase the number of the effective sampling taps, and then improve the performance of the microwave photonic filter notably. When the pump power was set to be 42.7 mW, a microwave bandpass filter with the 3-dB bandwidth of 0.15 MHz, the Q factor up to 100 and extinction ratio up to 20 dB was achieved. By employing a tunable optical delay line in the above fiber ring, a tunable microwave photonic filter has been realized through tuning the length of the optical delay line. The proposed tunable microwave photonic filter can find great applications in microwave signal processing and ROF system. CLC numbers: TN253 Document code: A Article IDRadio-over-fiber (RoF) technology is the most advantageous candidate for the next generation broadband wireless communication systems due to the combination-advantages of mobility of the wireless communication and the large bandwidth of the optical communication. Recently, microwave photonic filters have attracted much research attention, because of the inherent advantages of photonics technology, such as large bandwidth, low loss, ease to tune and reconfigure, and immunity to electromagnetic interference [1] . Microwave photonic filters can overcome the limitations of the traditional microwave filters, e.g., the electronic bottleneck and other sources of degradation, and show good application in the RoF systems. Several approaches to the implementation of microwave photonic filters have been proposed, such as two FBGs and gain media based recirculating cavity configuration [2] and superstructured FBG and dispersive media based filtering configuration [3] . Microwave photonic filters based on laser array and linearly chirped fiber Bragg grating (LCFBG), tunable laser and LCFBG are also proposed to achieve the reconfigurability and tunability [4][5][6] .In this paper, we present a low-cost microwave photonic filter with narrow passband, high Q factor and extinction ratio by introducing an erbium-doped fiber amplifier (EDFA) to the fiber ring based infinite impulse response (IIR) filter.

Fiber Sensor Systems Based on Fiber Laser and Microwave Photonic Technologies

“…In this schematic diagram, the output at port-3 of C1 is a typical response of microwave photonic notch filter and its frequency response can be expressed as [71]: $P_{\mathit{\text{out}}}=P_0{R}_{\mathit{\text{ref}}}(\lambda )\left|A+{\left(1-A\right)}^2\sum _1^{\infty }{false(AHfalse)}^{k-1}\right|$where: $H=(1-a)\sum _{i=1}^2{R}_{\text{italicsen}-i}false(\lambda false)e^{-j2\pi fn{L}_i/c}$…”

“…In this schematic diagram, the output at port-3 of C1 is a typical response of microwave photonic notch filter and its frequency response can be expressed as [ 71 ]: where: …”