Cascaded amplified Fabry–Perot spatial band pass filter for WDM application

Abstract In this work cascaded Fabry–Perot spatial filter was constructed with two and three duals uniform apodised fiber Bragg gratings. The characteristics of the constructed filter were investigated in terms of the narrowest and widest full width at half maximum (FWHM) in pm, interferometer noise in dBm and OSNR in dB. Smoothing filter would be obtained in the case of three cascaded dual FBGs with the narrowest and widest FWHM achieved by the proposed structures are 123.128 pm and 286.88 pm, respectively, with −16 dBm and −18.4 dBm interferometer noise and 8.7 dB, 6.39 dB optical signal to noise ratio in dB for widest and highest band pass filter, respectively. Narrowest FWHM and in sometimes can be called bandwidth of the filter was obtained in the minimum amplification range (15 dBm) while and widest one in the case of 24 dBm. For three cascaded amplified Fabry–Perot band pass filter widening in the optical bandwidth of the was obtained with bandwidth of 163.752 pm. Narrowing bandwidth was 68.572 pm in the case of dual FBGs and 81.323 pm in the case of single Fabry–Perot. Narrow pulse duration of 20 us of the transmitted spectrum was obtained in the case of three cascaded Fabry–Perot with 24 dBm nonlinear EDFA at 15 V P-P.