Backgr oundThe Dema nd for More BandwidthIn ternet, multimedia comm un icati ons, and etcMethods to In crease System CapacityWDM (Wavelength-Division Multiplexing)OTDM (Optical Time-Division Multiplexing) Benefits of WDM techniques Flexibility and scalability for a variety of network architecturesWDM techniques are the backbone ofmodem optical fiber networks(UIU)s o c a n o uR O 呂oP E e sb s U I c o q eJ Auy£E 】S L000L OO OJ L - -oss l000lNX F O W A服tita 0=寸、(E y fflp )OADM （AWG、光开关阵）调谐、高速集成光源OXCOADM光放大Key Devices for WDM Optical FiberNetwork SystemsLight Sources一Low-cost uncooled LDs一Directly modulated LDs一Modulator integrated DFB LDsHigh-Speed一Wavelength tunable/selectable LDsPhotodetectors SOA and Wavelength Converter AWG and RelatedState Key Lab on Integrated 2020/4/10OptoelectronicsLow-Cost Un cooled LDsApplications一Access network一Metropolitan transmission一Bit rate: 155 MB/s (FP-LDs) ~ 10 Gb/s (DFB-LDs)Requirements一Wide temperature range operation一Cost-effective structure for device fabrication一High efficiency and large toleranee for coupling output light intoa single mode fiberUn cooled Gain-Coupled DFB LDsStable single mode operation from ・40 to 85°CIn teg rated beam-expa nder for improved coupli ng tolera nee Gain-coupled DFB lasers with current-blocking gratingsgain-coupled DFB laser high-reflectivity film flared ridge waveguideInsulatorthickness tapered BEX p-electrodecurrent-blocki ng gratingn-lnP substratelow-reflectivity filmDirectly Modulated DFB LDsApplications一Gigabit Ether net一Metropolitan transmission一Bit rate: up to 10 Gb/s一Wavelength: 1.3 |im & 1.55 pirnLimitations一Limited transmission span (< 20 km) due to large linewidth enhancement factor oc (> 4)Modulation speed is limited by carrier relaxation oscillation10 Gb/s Directly Modulated DFB LDs forMetropolitan Data TransmissionBER Characteristics6 3 03 6 9-■-主0.2 0.5 1 2 5 10 20Frequency (GHz)Small-signal RF Response>j=1.5-5 pmD=17 psykm/nm10 Gb/SNRZ223-1L=10km-5-6-7倉申QcE」UJ*fw60•10-11Average ReceivedOptical Power (dBm)EA Modulator Integrated DFB LDsApplications一Trunk line transmission Bit rate: 2.5 Gb/s ~ 40 Gb/s Advantages一Compact size一Low coupling loss一Low frequency chirping一Reduced cost一Improved reliability10 Gb/s EA Modulator Integrated DFB LDsfor Trunk Line CommunicationsTransmission length: 100 kmFeature: Low power penalty (<1.5 dB) & Wide bandwidth (~14 GHz)EA ModulatorWindowstructureGrating DFB-LDp-lnP Cladding layern Electroden-lnPSubstrateIsolationtrenchSemi-insulati ngMultiquantum well layer(InGaAsP/lnGaA^10 Gb/s EA Modulator Integrated DFB LDsEye DiagramBER PerformaneeWavelength Tunable/Selectable LDs Advantages一Ability to restore failed channels一Reduced transmitter cost一In creased flexibility for future network managingWavelength Tunable vs. Wavelength Selectable一Wavele ngth Tun able LDs: Based on DBR structuresn Compact device structuren Poor reliability & Electric crosstalk at high frequency一Wavelength Selectable LDs: Based on DFB LD arraysn Relatively complicated device structuren Improved reliability and wavelength stabilityMulti-range Wavelength Selectable LDsFor use in back-up & add-drop in DWDM photonic networkDFB-LDs integrated with MMI coupler, SOA, and EA modulator Compact size (400 pm x 2840 jum)8 ch microarray一一、 DFB-LDs rHnG ・A ・P 、、8*1 MMI optical combinerSOA80 MimWindowMQWn-lnPEA-modulatorWindowIB 轡繆严的浮伽Multi-Range Wavelength Selectable LDArrays for DWDM Systems15 nm/chip wavelength selectable rangeWavelength & Threshold current1530154015501560157015801590Wavelength [nm]Lasing Spectra123456781234567812345678Channel<E一 luauno302010090807060504030 5 5 5 5 5 5 5Eu】 £6u(Da>>EM CDPOL 、A 七25°C -CWHigh-Speed PhotodetectorsConventional Configurations一Surface illuminated p■卜n photodetector一Avalanche photodetector (APD)Limitations一Limited bandwidth for APD detectorsTrade-off between bandwidth and efficiency for surface illuminated p-i-n detectorsCurrent Trend一Side illuminated structure => Waveguide p-i-n photodiodesWideband Waveguide Photodiodefor 40 Gb/s SystemsMonolithic receiver composed of multimode waveguide p-i-n photodiode and a HEMT distributed amplifierWGPD HEMT。