In this study, the gain clamping performance of Hafnia-bismuth-erbium co-doped fibre amplifier (HB-EDFA) using a lasing controlled structure with fibre Bragg grating (FBG) pair is presented. First, the gain and noise figure (NF) characteristics of a bidirectionally pumped HB-EDFA with very short lengths of heavily doped fibre are presented regarding its critical design parameters such as HB-EDF length, pump power, input signal power and signal wavelength. Then, the gain clamping performance of a bidirectionally pumped HB-EDFA having a C-band FBG pair with Bragg wavelengths of 1534 and 1542 nm is experimentally analysed. A good gain clamping capability was obtained using the proposed bidirectionally HB-EDFA design which has resulted in a dynamic signal input power range of 25 dB at 16 dB signal gain for 1.6 m HB-EDF length, and a wider dynamic signal input power range of 30 dB at 10 dB signal gain for 1.1 m HB-EDF length.

Fiber Bragg gratings (FBG) are ideal sensors for temperature, strain or vibration sensing applications with their advantages over conventional electronics sensor systems. In this paper, two different FBG sensor interrogation schemes based on broadband ASE source and tunable EDFRL source are demonstrated and compared. With both interrogator configurations, the response of the FBG sensor to temperature change is found to be linear and the sensitivities are measured as 11 pm/°C and 10.5 pm/°C, respectively. The experimental results have revealed that the optical power reflected from the FBG sensor is almost 20 dB higher with tunable EDFRL source than broadband ASE source. Thus, an interrogation method with tunable EDFRL can be suitable for remote, quasi-distributed sensor applications requiring high output power and OSNR.

A compact tunable C+L band erbium-doped fiber ring laser (EDFRL) with micro-electro-mechanical system (MEMS) based optical tunable bandpass filter was developed. The effects of erbium-doped fiber (EDF) length, output coupling ratio and pump power levels on its spectral characteristics have been analysed and optimized experimentally. With the parameters of EDF length of 6 m, output coupler ratio of 90:10 and both pump powers of 120 mW, a moderate output power level (~+4.5 dBm) and a wide wavelength tuning range (~80 nm) covering both C- and L-bands have been achieved.