hw10_sol - 8.1 Dry fibers have acceptabie losses over a...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 6
Background image of page 7
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 8.1 Dry fibers have acceptabie losses over a spectrai region extending from 1.3 to 1.6 ,um. Estimate the capacity of a WDM system covering this entire region using 40—Gb/s channels spaced apart by 50 GHZ. We first convert the 300-mn wavelengih range to frequency range as c c mamW) Amm—_fl3 fi—Ww~=@flnc V M a “Gamma Z For a channel spacing of 0.05 THz, the number of channels N is given by Nmfiflmfi:%5 Thus the WDM system capacity is NB m 865 X 40 2 34.6 Tia/s. 8.3 A 128 X 128 broadcasz star is made by using 2 X 2 directional couplets, each having an insertion loss of 0.2 (113. Each Channei Iransmiis 1 mW of average power and requires 1 jLL‘W of average received power for operation a: I Gb/s. What is the mimum transmission distance for each channeI? Assume a cabfe loss of 0.25 dBflcm and a loss of 3 dB from connectors and splices. For a broadcast star made by using 2 x 2 directionai coupiers, the power from each port is obtained using Eq. (5.2.2) or PN = (Pr/MU w area”. The 0.2 dB insertion loss of each directional coupier transiates into i w 5 "2 0.955. Using PT : 1 mW, and N m 228, we find PN : 5.66 yW or "222.47 dBm. Since receiver requires E ,LLW or —30 dBm, total E05365 should be be at most 7.53 dB, or afLm-i am 2: 7.53 dB. for given values of losses, me m 18.} km. 8.5 A Fabrwaerotfilter is used IO select 100 channels Spaced. apart by 0.2 nm. What should be the length and the mirror reflectivizies of the filter? Assume IO—Gb/s bit rate, a refractive index of 1.5 and an. operating wavelength of 1.55 34m. The free spectral range (FSR) corresponds to the spacing among transmission peaks. For the like: to be able to select all N channels, FSR should be larger than NAvCh, where Avg;2 is the channei spacing. Using FSR = Cf (2311.) > NAvck, we obtain L < 6/ (ERNAVCh). The 0.1mm channel spacing corresponds to Avch : L‘(A}LCh)/l2 m 25 GHz. Using this value with ' n 2 1.53110 N: 3000, we: obtain L < 80 pm. The mirror reflectivity R of the filter is obtain-ed from Eq. (8.2.2): min/'1? _. 1 l N<ngFm where “as m B/Avm. Using B m 10 Gin/s and n5 2 0.4,. we obtain R > 98.7% f0; N = 100. 8.12 Use a single fiber coupler and two fiber gratings Io design an addmdrop fifter. Explain how such a device firzcrions. Figure 842(1)) of the textbook shows a design that requires two fiber couplers and two fiber gratings. Its operation is based on a Mach~Zehnder interferometer. If we remove the second coupier, the device can still be used to drop a channel at port 2‘ However, it cannot be used to add a channel by launching it at port 2. Thus, the only solution is to fabricate the two gratings within the two cores of a fiber coupler. The gratings would reflect only one channel at the Bragg wavelength, which will appear at the unused inpot port. The remaining channel will appear at one of the output ports. We can also add the channel at the Bragg wavelength by launching it from the second output port. b 3 er: 7 \ W \W 7 [T bofik)@ k A a. A Macm- Eemder MTarF’erome-rer mgrmés sag 5pbr’r-h‘ng 1m m'pm beam acLuAmé {hi-o :m ?Cur+g. These beam/19; W312 mam/e aflgFa/WT PM“ ngr [F 9% 0? fine DPT/maxi [Daft/Id; as made wfigyw+§49w moww W6 mgmwwmg a swim ewf. Wham “fl/2392 “w; beam/‘5‘. mra made 79 m-réygwe a“; we 9m?“ F a i ‘1'?!"3 , l>r “D r’. < . We antique/sawrjmwg CHLFEMd 91/: 14mg WW 0? .4 A . t we, Mashv'aemmw, phme mg WWW V Eq’, 15.9 I "We +rmgm'mW-za "Waugh 0: MaeM~ZcMdeV “Hwy/m H’UWI ‘ww ,:-a?~a.- "1 \ r~ is 'wawsmfiém‘rvg, gm v aHLflN 6% (WT; mm “L “Bk-awe wag- 4;} The mm T1”W5%W‘Ftwmaf tam/L344 a gw‘eg; a)? we mergemwm, is ijffll : T T2. T; 3 [WSZL‘W’E{}][C§251 (mum) _ _ H [0692(71'0 “EMU M . = “T‘ 0092 WWW.) mm ...
View Full Document

This note was uploaded on 03/06/2012 for the course ENGINEERIN 605 taught by Professor Rahmir during the Spring '11 term at Wisconsin.

Page1 / 7

hw10_sol - 8.1 Dry fibers have acceptabie losses over a...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online