In this work we discuse the possibility of using an optical fiber laser constructed by two Bragg grating as a temperature sensor [1,2]. The device is based on measurement of the power transmitted through the Bragg gratings when the temperature ofone ofthese gratings is changed. Changes on the temperature results in a shift of reflection wavelength of the Bragg grating and therefore change a the transmition coefficient. The resulting change of the power at the laser output can be used for simple and exact measurement of the temperature. Experimental SetupThe experimental setup is shown in the figure 1. The laser cavity consists of a section of Erbium doped fiber and two Bragg gratings, acting as mirrors with maximum reflexion at 2=l 549 nm. A laser diode emiting at =98Onm was used for laser pumping, through the WDM. The power at both outputs was monitored while the temperature of the other Bragg grating (BG2) was kept constant. The output fiber ends were immersed to avoid Fresnel reflection. mn Figure 2 shows the dependence of the output power on the temperature of the Bragg grating BG1 . The Bragg grating BG2 was kept at a temperature of 73°C. Low output power is observed in the range of 60°C to 85°C. In this case it can be considered that the two gratings posses the maximun reflectivity at wavelength which coincide with laser one and there low output power is observed. In the range of 85°C to 1 02°C the reflection wavelength of the grating 2 begins to be displaced toward greater wavelengths and the laser wavelength does not coinside more with maximum reflexion wavelength and therefore leading an increase of the transmit power is begun to observe at the exit of the gratings. At 103°C an abrupt jump of the power of the signal is observed. This jump is detected very easy and can be used for temperature measurement. It depends on the temperature difference between Bragg grating only.

The gain dynamics of a semiconductor optical amplifier (SOA) were measured using pump-probe techniques for the amplification of 750 fs pulses, 6.5 ps pulses and multiwavelength pulses, obtained from an external cavity semiconductor mode-locked laser. Furthermore, the intracavity gain dynamics of an external cavity semiconductor mode-locked laser was measured under multiwavelength operation. The experimental results show how the inherent chirp in pulses from external cavity semiconductor mode-locked lasers result in a slow gain depletion without significant fast gain dynamics. This mitigates gain competition between wavelength channels and nonlinearities in the gain media (SOA), enabling the multiwavelength operation of external cavity semiconductor mode-locked lasers. Numerical simulations support the experimental results.