Studying The Output Performances Of The Apodized Fiber Grating Diode Lasers

The development of the dense wavelength division multiplexing(DWDM) technology requires that the wavelength spacing among channels be further lowered, and therefore it is indispensable that the lasing wavelength of the light source has high accuracy and stability.In recent years,the fiber grating(FG) external cavity semiconductor laser(FGL),regarded as one of the candidate light sources of DWDM systems,has received considerable attention.Compared to ordinary Bragg fiber grating, the reflectance spectrum of apodized fiber grating can significantly reduce the sidelobes,apodized fiber grating be the external cavity of semiconductor laser will have the better wavelength selectivity.In this paper,it will use transfer matrix method to study the external cavity semiconductor laser(ECSL).By changing the parameters of the laser,both the number and the location of the modes will vary.Based on the transfer matrix method,the wavelength which meets the condition of the transfer matrix is the oscillation modes. When the oscillation modes have been determined,the output characteristics of the apodized fiber grating diode lasers(AFGL) have been theoretically investigated.At the same time,we will analysis the influence to the ECSL by the different parameters of the external cavity FG.The output spectrum,the P-I curves and the side-mode suppression ratio of the spectrum have been numerical simulated.The results show that with the change of the maximum of the refractive index modulation depth△n₀,the spectral location will move in a certain range,the ECSL achieve the better output power.Under certain parameters,the modes out of the 3dB bandwidth have been inhibited.When the optical feedback is weak,the single mode operation with the side-mode suppression ratio(SMSR) more than 40dB can be achieved.