Large Dynamic Range Electromagnetic Field Sensor based on Domain Inverted Electro-Optic Polymer Directional Coupler Alan X. Wang Ray T. Chen Omega Optics Inc., Austin, TX -1-
Application of Electric Field Sensors: Electromagnetic Attack Alarming Medical Apparatuses Microwave-Integrated Circuit Testing Ballistic Control Health Protection (<100KHz) --
Electronic Sensor v.s. vs. Photonic Sensor Drawbacks of Conventional Electronic Sensor: Disturbance from electrical cables Narrow bandwidth Bulky size Advantages of Photonic EM Sensor: Free of disturbance to EM waves Broad bandwidth Compact size Precise measurement
Domain Inverted E-O Polymer Directional Coupler with Super High Dynamic Range DARPA MORPH E-O Polymer Domain Inverted Y-fed Directional Coupler -4-
What is E-O Polymer Materials? Chromophore + - Thin film - CLD1 V Host Polymer APC or PMMA Light ~ Pockels effect: Δn = 1 n 3 γe -5-
Materials Comparison Materials Polymers Si/SOI III-V LiNbO 3 Optical Loss (db/cm @1550nm) ~1 0. ~0.5 0. E-O efficiency (pm/v) 450 N/A <5 30 Bandwidth (GHz) 110 40 30 40 Fabrication Process Various CMOS RIE Ti diff. Integration Easy Standard Difficult No Cost Low Low Highest High Reliability Moderate High High High Improvement Potential Yes No No No -6-
Design of Domain Inverted E-O Polymer Directional Coupler Nonlinear Distortion in RF Photonics Signal RF Photonic link Signal + distortion E-O modulator Modulator f 1 f Third Order Intermodulation Distortion (IMD3) f 1 -f f -f 1 f 1 f RF I out = I0 I0 + cos[ φbias + Δφ( V )] Harmonic Signal -7-
Y-fed Directional Coupler based on Domain In erted Wa eguide Domain-Inverted Waveguide = = i i o R jb A jb A R M M R 1 1 1 R, S: Complex amplitude i i o S A jb A jb S S 1 1 1 H. Kogelnik and R. V. Schmidt, "Switches directional couplers with alternating ß", IEEE J. of Quantum Electron., vol. 1, pp. 396-401, July 1976 + = = = 1 1 ) ( n n h n V V f R Analytical Methods: Reduced simulation work Full spectrum coverage n n n dv V f d n h ) (! 1 = are the Taylor coefficients Full spectrum coverage Small errors -8-
Expression and amplitude of the signals from the Y-fed directional coupler Signal Frequency Amplitude (up to the 7th order expansion) DC 0 1/ Fundamental f 1, f 15 7 5 5 9 3 h7a + h5a + h3a + h1a 64 4 4 nd Harmonic f 1, f 0 IMD f 1 -f, f 1 +f 0 441 7 5 5 1 3rd Harmonic 3f 1, 3f h 7a + h5a + h3a 64 16 4 IMD3 f 1 -f, f -f 735 7 5 5 3 3 1 h 7a + h5a + h3a 64 8 4. 3 How to characterize the linearity of the optical modulators? V = a[sin( π f t) + sin(πf 1 t IMD3 is the most important t spurious signal because: It has the largest magnitude It is very close to the fundamental signals )] IMD3 suppression at 10% modulation depth
Design of Domain Inverted Modulator Schematic of the waveguide structure Simulation of the conversion length 3 μm.7 μm 3 μm UFC-170A LPD-80/APC, n=1.61, r 33 =80pm/V 0.5μm 5μm 10μm UV15-LV, n=1.49 Coupling length :lc=3.55mm at λ=1.55 μm -10-
Performances of YFDCs with different number of domains Name MZM Device 1 Device Device 3 Device 4 Type 1-domain 1-domain -domain 3-domain 4-domain Normalized Section Length s 1 =.8595 s 1 =.85 s =.85 85 s 1 =1.8859 s =1.5131 s 1 =.1884 s =.058 058 s 3 =.5464 s 3 =1.5383 s 4 =.6648 Average IMD3 43.6 51. 65. 97.5 110.3 suppression 10%~50% MD(dB) Driving Voltage 1.0.0.96 4.19 5.1 Maximum Modulation Depth 100% 7.6% 98% 96% 99.7% SFDR @ -145dB/Hz noise level(db/hz) 98 110 103 116 10 109 11 11 15 130 SFDR @-160dB/Hz noise level(db/hz) -11-
¾Device Fabrication UFC170A AJCJL1/APC V UV 15 LV UV 15 ~ ~ ~ ~ ~ ~ ~ Intrinsic silicon Hot plate -1-
Domain Inverted E-O Poling by Pulse Voltage Working Condition E-O poling direction EM Wave direction Top S S 1 +V Gold Gold Key Points: E-O poling without top cladding Domain inverted poling -V No bottom electrode Heavily Doped Silicon -13-
E-O Polymer Photonic EM Wave Sensor Characterization RF response @ 1GHz Xiaolong Wang, Beom-Suk Lee, Ray T. Chen, Large Dynamic Range Electromagnetic Field Sensor based on Domain Inverted Electro-Optic Polymer Directional Coupler, Invited Presentation, SPIE Photonics West conference, RF and Millimeter-Wave Photonics (Conference 7936), San Francisco, January -7, 7, 011
where ε 0 =8.854 10-1 F/m c=3 10 8 m/s E is the maximum amplitude of the electric field Minimum Electric Field 30V/m RF Power Density 0.3mW/cm Maximum 4 10 5 V/m 59KW/cm Solicitation Requirement: milliwatts per square centimeter to kilowatts per square centimeter Exactly Matched!
IMD3 Suppression MZ Modulator Fundamental IMD3 0dB 50dB Device 0: MZM Device 1: 1DM Y-fed DC Device : DM Y-fed DC Device 3: 3DM Y-fed DC Device 4: 4DM Y-fed DC Linear Modulator db higher h average IMD3 suppression from 10%~50% modulation depth 47dB higher IMD3 suppression @ 0% modulation depth Boem-Suk Lee, Che-Yun Lin, Xiaolong Wang, Jingdong Luo, Alex K.Y. Jen, and Ray T. Chen, Bias-free electro-optic polymer based two-section Y-branch waveguide modulator with -db linearity enhancement, Optics Letters, Vol.34, No.1, pp.377-379 (009) -16-
Spurious Free Dynamic Range MZ type Definition of Spurious Free Dynamic Range (SFDR) DC type Beomsuk Lee, Xiaolong Wang, Ray T. Chen, and Raluca Dinu, Electro-Optic Polymer Y-Brunch Directional Coupler Modulator with High Linearity, submitted to IEEE Photonic Technology Letters 11dB higher SFDR! -17-
Small Signal Modulation Measurement Laser Device EDFA 0 0 5 10 15 0 5 RF source λ=1.55μm Modulation depth = 4% Frequency range ~6.5GHz Photo detector onse (db) Respo -5-10 Microwave Spectrum -15 Analyzer -0 Frequency (GHz) 3-dB electrical bandwidth ~ 10GHz