Fiber optics devices for photonic communication and network 廖顯奎台灣科技大學電子系, 光電中心 台科大光纖光學實驗室 5/4 文化大學電機系 1
OUTLINE 1. Fiber Bragg gratings (FBGs). FBG-based Fiber lasers. FBG-based Optical amplifiers 4. FBG-based Optical Cross Connect device 台科大光纖光學實驗室 5/4 文化大學電機系 Optical Fiber Lab
Applications of FBG-devices in WDM point to point system 台科大光纖光學實驗室 5/4 文化大學電機系
kh 9 z SPECTRU ANALYZE M R - 6.5 GH z Applications of FBG-devices in WDM PON TX1 TX 1550/110nm WDM Raman Pump DCF 10KM SMF 0KM 1xn Splitter FBG1 FBG Tunable filter Tunable filter ONU1 ONU TX TX4 OTDR 856 Node E 1550nm 1550/110nm WDM 110nm FBG FBGn Tunable filter Tunable filter ONU ONUn A 1550nm 110nm 4 Optical Fiber Lab
Fiber Bragg Gratings (FBGs) Fabrication Fiber Bragg grating (FBG) λ B = nλ λ Β : FBG Bragg wavelength n: fiber index Λ: grating pitch 48 nm Excimer laser 台科大光纖光學實驗室 5/4 文化大學電機系 5 Optical Fiber Lab
Fiber Bragg Gratings Low transmission < -0 db Narrow bandwidth 10/0/0-dB BW: 0./0.5/0.6 nm transmission spectrum 台科大光纖光學實驗室 5/4 文化大學電機系 6 Optical Fiber Lab
Fiber Bragg Gratings (FBGs) Temperature compensated FBG Temperature coeff. 15 pm/c 1547 After compensation Before compensation Wavelength(nm) 1546 1545 1544 0 40 60 80 100 Temperature(Degree C) 台科大光纖光學實驗室 Home-made FBG 5/4 文化大學電機系 7
Fiber Bragg Gratings (FBGs) Strain-Tunable FBG -0 Power (dbm) -40-50 -60-70 (a) -80 1545.7 nm 1548.17 nm 1551.8 nm 1554.16 nm 1557.09 nm (c)nm 1 (b) Res : 0.05 nm 1544 1546 1548 1550 155 1554 1556 1558 1560 Wavelength (nm) Figures (a) wavelength tuning using screw, and (b) rough tuning up to 1 nm, (c) fine tuning 1.6 nm,. nm, 4.8 nm and 6.4 nm, respectively. 台科大光纖光學實驗室 8 5/4 文化大學電機系
FBG-based Fiber Lasers Tunable fiber laser Nearly single frequency fiber laser 台科大光纖光學實驗室 9 5/4 文化大學電機系 9
Applications Optical component characterization Optical measurement applications Analysis of material discontinuity/thickness Optical source for optical wireless smart structure likes MEMS Rapid wavelength-swept laser source for OCT Optical communication Optical sensor systems 台科大光纖光學實驗室 10 5/4 文化大學電機系 10
FBG-based Tunable Fiber Lasers Conventional fiber lasers EDF TFBG OSA Broadband fiber laser Broadband Fiber Mirror 1480/1550 WDM PM Pump LD IEEE J. Quantum Electronics 008 fiber laser includes a BFM. Hence, the device can ignore the problem of shifting wavelength and/or wavelength misalignment between FBG pair. Improvement of the pumping efficiency by recycling the residual pump power to the laser cavity. 台科大光纖光學實驗室 11 5/4 文化大學電機系 11
FBG-based Tunable Fiber Lasers BFM reflectivity 98% for 1550 nm and 80% for 1480 nm. FBG R%:50% Pump LD 1480 nm Er+ ion concentration 800ppm FBG changes in wavelength by tension. Power variation =<±1.0 db EDF absorption 19.dB/m@151nm 40 10 5 0 0 5 57.9dB 0 1544.78nm 1.14mW Power (dbm) Output Power (mw) 0 159.1 nm 15.19 nm 1.6 dbm 11.81 dbm 1561.99 nm 1551.8 nm 1.7 dbm 1.18 dbm -10-0 -0 15-40 10-50 5-60 150 150 Res : 0.05nm VBW : 100Hz 0 0.0 0.1 0. 0. 0.4 0.5 0.6 0.7 0.8 0.9 1.0 FBG's Reflection Ratio FBG reflectance 台科大光纖光學實驗室 SMSR 1540 1550 1560 1570 1580 Wavelength (nm) overlapping spectra 1 1 5/4 文化大學電機系
FBG-based Tunable Fiber Lasers Measured @1545nm (C Band) Slope efficiency Transfer efficiency above 0% SMSR 50 db 4.7mW η = in P P Las th P ( P P ) η : transfer efficiency, in P p th P p :input pump power :threshold pump power NTUST (Taiwan Tech) 國立臺灣科技大學 1
Nearly Single-Frequency Fiber Laser In a cleaved-coupled-cavity (C ) laser device, two different laser optical cavities L and D (different lengths) are coupled as shown in left Figure. These two different set of modes coincide only at far spaced intervals as indicated in the right Figure. L (a) D Active layer In L In D In both L and D Cavity Modes (b) λ λ λ Cleaved-coupled-cavity (C ) laser?1999 S.O. Kasap, Optoelectronics (Prentice Hall)
Nearly Single-Frequency Fiber Laser The proposed SF operation fiber laser by adding one subring cavity and a piece of gain fiber as absorber. Laser Physics 010 Optical Fiber Lab 15
Nearly Single-Frequency Fiber Laser (a) (b) (c) Figures (a) Power stability and wavelength variation in a 0-minute observation, (b) lasing power and optical signal-to-noise ratio (SNR), and (c) lasing wavelength at 1550. nm using saturable absorber. Optical Fiber Lab 16
Nearly Single-Frequency Fiber Laser (a) (b) (c) Figures Measured frequency spectra with (a) neither subring cavity nor absorber, (b) subring cavity only, and (c) both subring cavity and absorber, respectively. Optical Fiber Lab 17
FBG-based hybrid fiber amplifiers Applications WDM long-haul system and optical network. Bidirectional transmission Compensate the signal power of splitting loss, fiber and/or free space attenuation 台科大光纖光學實驗室 5/4 文化大學電機系 18 Optical Fiber Lab
FBG-based hybrid fiber amplifiers Intensity (db) Pump-Sharing Concept pump LD X% Y% Centre at 1575 nm C-EDFA X%+Y%=100% L-RFA f λ = λ f f = λ c = 94.9nm If λ= 1480 nm, then f = -1THz and λ=94.9 nm are the frequency and wavelength shift, respectively. The maximum amplified wavelength is 1574.9 nm. 1480 nm 150 nm 1580 nm Wavelength (nm) Optics Express 007 Figure A concept using a single pump LD for both C-band EDFA and L-band RFA amplification using such a 1480 nm pump LD. 台科大光纖光學實驗室 19 5/4 文化大學電機系 19
Uni-dir hybrid fiber amplifiers Parallel type of hybrid EDFA/RFA 1 Input Output C/L WDM C-band EDFA EDF m By-pass EDF Pump reflector A 1480nm Pump LD Ratio coupler C/L WDM Com. DCF Opt. Comm., Aug. 009 C L-band Ch. :1480/1550 WDM Coupler : C/L WDM Coupler EDF: erbium-doped fiber RFA: Raman fiber amplifier DCF: dispersion compensation fiber PBC: polarization beam combiner SMF: single mode fiber ISO: isolator DCF L DCF C1 DCF C FBG L1 FBG L FBG C1 FBG C C-band Ch. Pump reflector B 0 NTUST (Taiwan Tech) 國立臺灣科技大學
Uni-dir hybrid fiber amplifiers WDM channels dispersion management The dispersion (ps/nm) map for SMF and DCF. Total residual dispersion and extra DCF length required for WDM channels individually. 台科大光纖光學實驗室 1 5/4 文化大學電機系 1
Uni-dir hybrid fiber amplifiers WDM channels gain equalisation The net gain spectra and FBGs reflectivity of the proposed configuration, (b) before gain equalization and (c) after gain equalization. 台科大光纖光學實驗室 5/4 文化大學電機系
C band Input signals C-band Output L-band Bi-dir hybrid fiber amplifiers G on off Ps ( pumpon) = P ( pumpoff ) s = exp( g R Output L P N.F. 10log( hυb eff ± A ref [ P ( L) G net + p (0) + P 1 + G net ) p ( L)]) Intensity ( a.u. ) Pump power 1495 Raman Shift ~ 1.THz 1580 Wavelength(nm ) λ = 98.4 nm 1610 C-band L Input band signals L-band RC:ratio coupler (1:9) Pump LDs:500mW@1495 nm EDF: m DCF:11 km f f λ = -λ = λ f c
Bi-dir hybrid fiber amplifiers gain and noise figure 0 5 Pin = -10 dbm Pin = -15 dbm Pin = -0 dbm 5 0 Pin = -10 dbm Pin = -15 dbm Pin = -0 dbm Gain (nm) Noise Figure (db) 0 15 10 5 0 10 8 6 4 0 L- 150 155 1540 1545 1550 1555 1560 band Wavelength (nm) Pin = -10 dbm Pin = -15 dbm Pin = -0 dbm L band RFA 0 1570 1580 1590 1600 1610 150 155 1540 1545 1550 1555 1560 Wavelength (nm) Gain (db) Noise Figure (db) 15 10 5 C band EDFA 0 1570 1580 1590 1600 1610 8 6 4 Pin = -10 dbm Pin = -15 dbm Pin = -0 dbm Wavelength (nm) Wavelength (nm) 4
Reconfigurable Multiwavelength Optical Cross Connect (RM-OXC) Applications 1. Allows the optical network to be reconfigured Optimize traffic patterns, provide the routing function, facilitate network growth, and enhance network survivability.. Optimization of capacity allocation, management and scalability of network size. 5
x RM-OXC Bar State bar & cross states Cross State
x RM-OXC Operation Principle l 1, l, l I 1 I I 1 OC 1 FBG FBG' 1 OC FBG" 1 FBG" 4 FBG" 1 FBG OC FBG 1 4 1 4 FBG' FBG' O 1 O O l 1 l l 1. w/o wavelength interchange: all FBGs are non-strained. w/ wavelength interchange: the corresponding FBG s (between two ports) are strained tuning. Cross-connect among one another fiber links: all corresponding FBGi travel in the same direction are strain tuning. 7 7
x RM-OXC λ 1λλ... λ n I1 λ λ λ... 1 λ n OC1 EDF 1 OC4 1 4 4 1 FBG 1 FBG 1 FBG FBG λ λ λ... 1 λ n O1 λ λ λ... 1 λ n λ λ λ... 1 λ n I λ λ λ... 1 λ n λ λ λ... 1 λ n I λ λ λ... 1 λ n FBG FBG 1 n OC EDF FBG 1 4 FBG 1 FBG FBG n FBG n EDF 1 4 OC Pump shared FBG n OC5 4 1 FBG 1 FBG to EDF 1 to EDF to EDF FBG n 4 1 OC6 FBG n FBG 1 FBG λ λ λ... 1 λ n O λ λ λ... 1 λ λ λ... 1 λ n λ n O λ λ λ... 1 λ n Figures (a) the conventional RM-MOXC, (b) the proposed RM-OXC 8
I 1 /O' 1 I /O' I /O' Power (dbm) Power (dbm) -0 RMB-OXC scheme w/o amplifier RMB-OXC scheme w/ amplifier FBG 1 FBG FBG 1 ROC FBG 1 EDF 4 FBG 1 FBG FBG FBG EDF 1 4 ROC Pump shared ROC 1 ROC 4 1 4 EDF 1 4 1 FBG 1 FOAN 011 FBG FBG ROC 5 4 1 FBG 1 FBG to EDF 1 to EDF to EDF FBG 4 1 ROC 6 FBG FBG 1 FBG Figs. 7. O 1 /I' 1 O /I' O /I' Power (dbm) Power (dbm) Power (dbm) Power (dbm) 0 0-10 -0-0 -40-40 -60-50 -80-60 0 0-10 -0-0 -40-0 -40-60 -50-80 -60 0 0 SNR :: 9.0 51. db db -10-0 -0 Ch4: -68. dbm -40-0 Ch: -6.5 dbm Ch: -66.98 dbm Ch1: -61.4 dbm -40-60 Ch: -41.79 dbm -50-80 -60 SNR : 9.48 db SNR : 65.1 db Ch1: -18.19 dbm 1544 1544 1546 1546 1548 1548 1550 1550 155 155 SNR : 4.7 9. db Ch: -9.4 dbm Ch1: -44.0 dbm Ch1: -51.5 dbm Ch: -60.48 dbm Ch: -6.4 Ch5: -56.14dBm Wavelength (nm) (nm) Ch: -18.85 dbm Ch5: -51.84dBm 1544 1544 1546 1546 1548 1550 155 Ch1: -46.89 dbm Ch1: -9.14 dbm Ch: -41.5 Ch: -47.8 dbm Wavelength (nm) Ch Ch5: -8.9dBm Ch4 Ch6: -61.dBm Ch7: -17.86 dbm Ch5: -18.5 dbm Ch5: -9.59dBm Ch6: -45.6dBm Ch7: -9.7dBm 8 db Ch8 Ch6: -58.74dBm Ch7: -6.1dBm Ch7: -4.99dBm 1544 1544 1546 1546 1548 1548 1550 1550 155 155 O 1 O O
x RM-OXC 5 Power Penalty (db) 4 1 0 reflection twice Power Penalty (db) reflection once -19.8 db -0-8 -6-4 - -0-18 -16 Intraband Crosstalk Level (db) Figures (a) Power penalty against the channel spacing, and (b) Power penalty against the intraband crosstalk. Fiber Optics Lab., NTUST 0
Conclusion 1 The requirements for FBG components in lightwave communication is rising rapidly FBGs is emerging as an enabling technology for a wide range of new devices Usually, FBGs offer the only cost effective solution for high speed transmission 4. The ability to select wavelengths precisely in fiber optic systems make FBGs as invaluable and versatile optical components. 1
Fiber Optics and Communication Lab. People Advisor: Professor S.-K. Liaw 10 Master students and PhD students NTUST (Taiwan Tech) 國立臺灣科技大學
Prototype Products 0 0 First grating 1540.6nm 150.6nm -0.55dBm 1540.6nm -0.9dBm 1551.44nm 0.44dBm Second grating 1556.44nm 1561.44nm 0.5dBm Power (dbm) -0-40 -60 155.6nm -0.7dBm 1546.44nm 0.4dBm 1556.44nm 0.8dBm -80 150 150 1540 1550 1560 1570 Wavelength (nm) ROADM Tunable fiber laser OXC & OADM Temp. compensated FBG Miniature EDFA an ITRI project
Acknowledgement National Science Council, Taiwan Fiber Optics and communication lab, Optical Networking lab, Taiwan Tech (NTUST) The coauthors and co-inventors of the following references. 1. Opt. Commun. vol. 84, 57-578 (011).. IEEE J. Quantum Electronics, vol. 44, 50-57, 008. OSA J. Optical Networking, vol. 7, 66-67, 008 4. USA paten no. US7800744 B, issue date: 1 Sep. 010 5. Book chapter: Intech publisher, Vienna, Austria 011. 4