2. Jump to first page Optical Channel Monitor Liang-yu Chen Jian Li Arvind Narayanaswamy Dilan Seneviratne Zhenhai Zhu Mentored by Prof. George Barbastathis

3. Outline IntroductionIntroduction Grating DesignGrating Design ActuatorActuator FabricationFabrication Sub-componentsSub-components Drive signalDrive signal Assembly and alignmentAssembly and alignment SummarySummary

4. Goals Device Monitor optical power in fiber carrying WDM signalsMonitor optical power in fiber carrying WDM signalsApplications Real-time optical performance monitoring of DWDM networksReal-time optical performance monitoring of DWDM networks Optical add/drop monitoring and diagnosticsOptical add/drop monitoring and diagnostics EDFA gain balancingEDFA gain balancing

5. Design Requirements Scan 10 wavelengths ( 1 … 10 ) in 10msScan 10 wavelengths ( 1 … 10 ) in 10ms 5% diffraction efficiency5% diffraction efficiency Central wavelength: 1.5  mCentral wavelength: 1.5  m Operate under 50VOperate under 50V +/- 10% variation between 1 and 10+/- 10% variation between 1 and 10

6. Device concept

7. Grating operation actuator grating

8. Outline IntroductionIntroduction Grating DesignGrating Design ActuatorActuator FabricationFabrication Sub-componentsSub-components Drive signalDrive signal Assembly and alignmentAssembly and alignment SummarySummary

9. Grating design Type of grating - amplitude or phaseType of grating - amplitude or phase Pitch and spacing between beams (nominal duty cycle)Pitch and spacing between beams (nominal duty cycle)x   s p tx 1 0 s p Amplitude grating Phase grating

10. Grating Design Angle of incidenceAngle of incidence Thickness of beamsThickness of beams 0 +1 0 +1 -2 Normal incidence Incidence at an angle

11. Design challenges Focusing on the detectorFocusing on the detector  spot size  spot overlap         detector

12. Design challenges Focusing on the detectorFocusing on the detector  spot overlap n n-1 n-1 n+1 n+1

13. Overview of the Whole Device Large number of grating beams neededLarge number of grating beams needed Natural Frequency is too lowNatural Frequency is too low Split into piecesSplit into pieces Efficiency reduction caused by comb drive and space between two piecesEfficiency reduction caused by comb drive and space between two pieces

14. Outline IntroductionIntroduction Grating DesignGrating Design ActuatorActuator FabricationFabrication Sub-componentsSub-components Drive signalDrive signal Assembly and alignmentAssembly and alignment SummarySummary

15.   Lumped model   Resonant frequency >1khZ, for fabrication limitation and operation limitation Grating Design

16. Grating Design (2)   Resonant frequency Grating beam: 4khZ Whole system: 1.5khZ   Number of gratings for each piece: N=500   Displacement of the gratings: N*22.5nm=11.3um   Actuation force Needed: k*22.5nm=53uN

17. Actuator Requirements:Requirements:  Displacement: 11.3um  Force 53  N  Voltage 0-50V Options:Options:  Electrostatic: Ease of fabrication, Low power, high stroke  Piezoelectric: Low strain  Thermal: High power, long response time

18. Electrostatic Actuators Comb DriveComb Drive Capacitor PlateCapacitor Plate Zipping ActuatorZipping Actuator Electrostatic actuators - ease of fabricationElectrostatic actuators - ease of fabrication Different electrostatic actuatorsDifferent electrostatic actuators

19. Electrostatic Actuators (2) Force Displacement curveForce Displacement curve

20. Results Displacement 20umDisplacement 20um Force 255uN @ 50VForce 255uN @ 50V 4 times larger than needed4 times larger than needed Can be used to calibrate the deviceCan be used to calibrate the device Air damping: quality factor Q ~ 30Air damping: quality factor Q ~ 30

21. Outline IntroductionIntroduction Grating DesignGrating Design ActuatorActuator FabricationFabrication Sub-componentsSub-components Drive signalDrive signal Assembly and alignmentAssembly and alignment SummarySummary

22. Two masks, SOI wafer, KOH back etch Fabrication: overview

23. Fabrication SOI Silicon Silicon Oxide Photo Resist DRIE strip PR KOH etch HF wet etch

24. Outline IntroductionIntroduction Grating DesignGrating Design ActuatorActuator FabricationFabrication Sub-componentsSub-components Drive signalDrive signal Assembly and alignmentAssembly and alignment SummarySummary

25. Detector Sensitivity – flat response at 1.5  mSensitivity – flat response at 1.5  m 1.5  m 1.49625  m to 1.50375  m

26. Lenses Collimating systemCollimating system  Lenses Transmission - > 99.5%

27. Lenses (2) Magnification systemMagnification system   M = 22 = f 1 /f 2 = 44mm / 2mm Bi-convex EFL- 44 mm Bi-concave EFL- 2 mm f1f1 f2f2

28. Outline IntroductionIntroduction Grating DesignGrating Design ActuatorActuator FabricationFabrication Sub-componentsSub-components Drive signalDrive signal Assembly and alignmentAssembly and alignment SummarySummary

29. Assembly and Alignment Requirements:Requirements:  Tolerances permissible by design Perpendicular to optical axis – 0.2 – 0.4  m Along optical axis - 0.8  m  Precision achievable by assembly – +/- 10nm Assembly outsourcingAssembly outsourcing  Axsys Technologies  Zygo - From Axsys Technologies

30. Calibration Detector plane     Detector   Total swing possible   Total swing required Total permissible error = (    

31. Calibration (cont.)

32. Outline IntroductionIntroduction Grating DesignGrating Design ActuatorActuator FabricationFabrication Sub-componentsSub-components Assembly and alignmentAssembly and alignment Drive signalDrive signal SummarySummary

33. Drive Signal

34. Drive Signal (Cont.) AC/DC 110/60 Oscillator + - 50V AC/DC 110/60 3.3V + -

35. AC/DC 110/60 + - 50V

36. Conclusion(s) Central wavelength: 1.5  m Scan 10 wavelengths in 10ms 5% diffraction efficiency (+/- 10%) Operate under 50V Operate under 50V Device size - ~ 10cm X 10cm Easily calibrated Minimum alignment In-expensive fabrication