1 / 13

Dynamic Dispersion Compensator

Dynamic Dispersion Compensator. Christi Madsen, James Walker, Joseph Ford, Keith Goossen, David Neilson, Gadi Lenz. References: "Micromechanical fiber-optic attenuator with 3 microsecond response"  

Mercy
Download Presentation

Dynamic Dispersion Compensator

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dynamic Dispersion Compensator Christi Madsen, James Walker, Joseph Ford, Keith Goossen, David Neilson, Gadi Lenz References: "Micromechanical fiber-optic attenuator with 3 microsecond response"   J. Ford, J. Walker, D. Greywall and K. Goossen, IEEE J.of Lightwave Tech. 16(9), 1663-1670, September 1998 "A tunable dispersion compensating MEMS all-pass filter"    Madsen, Walker, Ford. Goossen, Nielson, Lenz, IEEE Photonics Tech. Lett. 12(6), pp. 651-653, June 2000.

  2. Fiber core index depends (slightly) on l Any modulated signal has nonzero linewidth Chromatic dispersion is the result: Spread in arrival time after signal transmission Fiber core index depends (slightly) on l Any modulated signal has nonzero linewidth Chromatic dispersion is the result: Spread in arrival time after signal transmission 100 km 1 km 500 km 1500 km Fiber spans are “dispersion compensated” But residual dispersion at 3000 km D = 1050 ps/nm V. Srikant (Corning) OFC 2001 DCF DCF DCF DCF DCF Is that OK? Depends on data rate B and length L: (relation for 1 dB power penalty; Tigye Li, Proc. IEEE, 1993) B2DL ~ 105 ps/nm (Gb/s2) MARGINAL Cumulative dispersion budget: 1000 ps/nm @ 10 Gb/s 63 ps/nm @ 40 Gb/s CRITICAL Chromatic dispersion in long-distance telecom

  3. Equalizer Dispersion Compensator I BER feedback Uncompensated Compensated Dynamic chromatic dispersion compensation

  4. Gires-Tournois Interferometer Periodic spectral phase response L / 2 Round Trip Delay Free Spectral Range Phase-only “all-pass” filter • For a lossless filter, magnitude response = 1 (allpass!) • Periodic Gaussian dispersion feature (DCF requires linear chirp) • Approximately linear dispersion over a limited bandwidth Madsen, Walker, Ford, Goossen & Lenz, ECOC 1999; see also recent IEEE LEOS article

  5. 1 2 3 4 Increases passband width and total dispersion Ripple = dev. from ideal linear response Multi-stage Filter Dispersion Madsen, Walker, Ford, Goossen & Lenz, ECOC 1999

  6. Voltage Response measured theory input input reflect reflect Vdrive l/4 SiNx l/4 SiNx PSG PSG Drive voltage (V) Silicon Silicon transmit transmit 0 < Vdrive < 30V 3l/4 < gap < l/2 0 < Vdrive < 30V 3l/4 < gap < l/2 Vdrive The “MARS” resonant MEMS modulator MARS (Membrane Anti-Reflection Switch) analog optical modulator l/4 Silicon Nitride “drumhead” suspended over a Silicon substrate Ford, Walker, Greywall & Goossen, IEEE J. Lightwave Tech. 16, 1998 Greywall, Busch & Walker, Sensors & Actuators A A72, 1999. Goossen, Arney & Walker, IEEE Phot. Tech. Lett. 6, 1994

  7. £ £ 0 R 70% L/2 2 = r R 100%Reflector (dielectric enhanced gold mirror) Tunable Partial Reflector V Substrate MARS All-Pass Filter Double polysilicon MEMS structure (flat l response, no charging) 411 um thick Silicon (100 GHz FSR) 2 control parameters per stage: MEMS voltage controls front mirror reflectivity (phase feature amplitude) Substrate temperature controls free spectral range (phase feature location) Madsen, Walker, Ford Goossen, Neilson & Lenz, IEEE Phot. Tech. Lett. 12, 2000

  8. optical breadboard package Vmirror TTEC controller input d $ D f f output ferrule collimator device hermetic MEMS VOA package Fiber-coupling package Key optical package parameters Lens focal length f = 3 mm Fiber separation d = 125 um Illuminated diameter D = 600 um MEMS device diameter 1250 um Substrate thickness t = 411 um Package loss (mirror at device plane) 0.4 dB

  9. Awindow-Afeatures Awindow Scatter = ( )N Cavity round-trip loss Absorption = (e-aL)N a = 10-4/cm Reflection = (Rmirror)N device R = 98.5% T = 99.3% Shift = 10-0.434(NdT/nF)2 Dy = 5 / 600 um Defocus = f(Nf) package fmembrane< 444 mm (20 um / pass) Coupling = To T = 93.3%

  10. 1 Measured Phase & Amplitude Wideband (30 nm) Transmission Single filter response Madsen, Walker, Ford Goossen, Neilson & Lenz, IEEE Phot. Tech. Lett. 12, 2000

  11. Tuned for 50 GHz bandwidth and 100 GHz (0.8 nm) FSR 1 2 Negative Positive Madsen, Walker, Ford Goossen, Neilson & Lenz, IEEE Phot. Tech. Lett. 12, 2000 2-stage DCF results Design: Dispersion goal = +/-104 ps/nm; predicted ripple of +/- 2.5 ps Result: Set at +/- 102 ps/nm, yielded ripple of +/- 2.5 ps

  12. 2x dispersion for 30 GHz bandwidth and 100 GHz (0.8 nm) FSR 1 2 Madsen, Walker, Ford Goossen, Neilson & Lenz, IEEE Phot. Tech. Lett. 12, 2000 2-stage DCF results (continued) 200 ps/nm range, 1.5 ps ripple (further improvement in loss uniformity required)

  13. Current status: Still R&D! Optical performance (loss uniformity) needs to be improved Control algorithms need more development Dispersion compensation not critical until 40 Gb/s deployed

More Related