1、Solutions of Chapter 8-91. A coupler has one input port and 16 output ports, all output ports are equal. If the input signal power is -10dBm，computer the power of one output port. Solution: When light is transmitting from a fiber of core radius to one having core radius b, suppose and the both fiber

2、s are step-index and multimode. Computer the loss.Solution:2. Sketch a three-wavelength fiber-grating demultiplexer, showing how the total three wavelengths ,can be detected individually.(Hint, Fig. 9.48 in the textbook)Solution:The device consists of 4 couplers and 4 gratings. The left 2 gratings a

3、re designed to reflect at wavelength , and transmit the other two wavelengths, while the right 2 gratings are designed to reflect at wavelength , and transmit the wavelength . Thus, the total three wavelengths can be detected individually3. A four-port directional coupler (DC) shows below, assume ,w

4、rite the expressions of Throughput Loss, Tap Loss, Directionality, Excess Loss and Splitting Ratio. Solution:1) Throughput Loss LTHP = - 10 log (P1 /P0 ) 2) Tap Loss LTAP = - 10 log (P2 /P0) 3) Directionality LD = - 10 log (P3 /P0 ) 4) Excess Loss LE = - 10 log (P1 + P2) /P0 5) Splitting Ratio SR= (

5、P1/P2)4. A Bragg grating is resonant at 1550nm. The grating will be tuned thermally. The increase in grating period from an increase in temperature is 0.1% per .1) Calculate the grating period.2) What is the change in resonant wavelength per ? Give the answer in nm/ .Solution: assume the refractive index of fiber core is 1.51) accordi