Abstract

Many attractive features of erbium fiber laser have been reported recently^1-4 with regard to their applications in both communications and sensing systems. In particular, we have demonstrated that the erbium fiber Bragg grating laser (EFBGL) sensor has an extremely high strain sensitivity of 10⁻¹⁴/√Hz¹ and is readily adaptable to wavelength-division multiplexing (WDM) in sensor array application.² A desirable configuration of deploying these EFBGLs for sensors array application would consist of a series of these short cavity fiber lasers multiplexed together using the WDM scheme, collinearly pumping these lasers with a single pump laser and interrogating their outputs with a single read-out interferometer.' Salient features of this particular configuration include the ability to use a single pump laser to collinearly pump a serial fiber laser sensor array, the ability to wavelength multiplex EFBGL sensors by using a different Bragg grating wavelength for each laser, and the ability to use a single read-out interferometer to interrogate wavelength encoded signals from a11 sensors with ultrahigh resolution, thus allowing the number of components such as pump lasers, read-out interferometers, and WDM couplers required for a EFBGL sensor array operation to be min-imized. However, minimum detectable signal (noise) of each wavelength channel and cross talk between different channels are crucial factors in determining the viability of this serial configuration of fiber laser sensor array. In this paper, we report measurements of the noise and cross talk of a WDM EFBGL sensor array of four elements in series using collinearly pumping by a diode laser at 980 nm and a single read-out interferometer. Potentially, a single pump laser can be used to provide optical pump power to a EFBGL sensor array of 32 channels by using the full32-nm gain bandwidth of the erbium fiber and 1-nm channel separation.

© 1996 Optical Society of America