Stress-Optical Phase Modulator
Mach-Zehnder Interferometer System
Stress Distribution in Optical waveguide structure
LioniX BV, PO Box 456, 7500AL Enschede, The Netherlands, +31-53-2030053, info@lionixbv.nl
-Phase Shift in Propagating Optical Beam
Conclusions
PZT layer Pt_ top electrode Pt_botton electrode X-direction Z-direction L W_TopElectorde t =2 mPZT tsubstrate=550 m wPt-electrode tPt-eletrode=0.1 m wcore=4.4 m Y-direction X-direction tcore=0.03 m tdown-clad=8 m tup-clad=8 m Si_Substrate Thermal_SiO2 LPCVD_Si3N4 PECVD_SiO2 Pt Ta Resist PZT -10 -5 0 5 10 526 528 530 532 534 536 538 540 Y ( m) X (m)Poynting vector distribution
2 of TM00 ( G W/m ) 0 100 200 300 400 500 -10 -5 0 5 10 -120 -100 -80 -60 -40 -20 0
Normalized poyinting vector distribution of TM00 ( log scale-dB ) X (m) 0 10 20 30 40 50 60 −60 −40 −20 0 20 40 60
Stress distribution (MPa)yy
X (m) 500 505 510 515 520 525 530 535 540 Y ( m) −60 −40 −20 0 20 40 60 500 505 510 515 520 525 530 535 540
Stress distribution (MPa)xx
X (m) Y ( m) 0 10 20 30 40 50 60 X (m) Y ( m) −20 −10 0 10 20 525 530 535 540 0 1 2 3 4 5 6 7 8 -4 x 10 Change of refractive index nxx
−20 −10 0 10 20 525 530 535 540 0 1 2 3 4 5 6 7 8 -4 x 10 Y ( m) X (m)
Change of refractive index nyy
0 10 20 30 40 50 60 70 80 90 100 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 -4 x 10
Top electrode width (m)
(b)Modification of waveguide n for TM polarizationeff
n eff t =m , L =13.99 mmPZT t =m , L =4.45 mmPZT t =m , L =5.51 mmPZT t =m , L =7.66 mmPZT
Si <100> grown SiOThermally
2 PECVD SiO2 LPCVD Si N3 4 PZT Pt E (GPa) 130.2 57 75 270 95.2 137.9 3 (kg/m ) 2329 2200 2200 2500 7500 21090 0.28 0.17 0.24 0.27 0.35 0.25 n 3.48 1.45 1.45 1.98 - -Material Properties
Values for materials parameters used
The geometrical parameters such as top electrode width, SiO2 layer thickness and PZT thickness are varied to find the optimal structure
with maximum tunability. The results show a structure with 8 m top cladding thickness, 2 m PZT layer thickness and around 30 m top electrode
width offers the most optimum structure for propagating light with TM polarization. According to the simulation results, this structure can
provide a phase shift in the propagating light if the interaction length will be in order of 5 mm. To observe the stress effect experimentally,
the Mach-Zehnder interferometer structures with various top electrode widths ,ranging between 10 and 100 m, have been fabricated in LioniX BV.
As future works, the characterization of the fabricated structures will be performed.
Optical modulators are devices that can be used to manipulate the properties of optical beams, e.g. a laser beam, in integrated optical chips. A wide range of optical modulators are used in very different application areas, such as in optical fiber communication, displays, for active Q switching or mode locking of lasers, and in optical metrology. Phase modulators are optical modulators that can be used to control the phase of an optical beam. For decades, it has been a challenge to increase the efficiency and the modulating speed. We tackle the problem by applying the stress-optic effect induced by depositing a piezoelectric layer on top of an integrated optical device. By applying a static electric field to the PZT layer, a relative phase difference is induced between two arms. When between the two arms equals (2n+1) where n is an integer number, destructive interference occurs, corresponding to 0 output for the modulator. In this work, we search for the optimized optical waveguide structure including a thin layer of PZT on top to find the lowest interaction length inducing optical phase shift of .
Left figure shows the z-component of the Poynting vector distribution of TM00 (0th order of transverse magnetic field) mode. Right figure is the log-scale of the mode in dB unit.
The figures above show the normal stress distributions, and in the xx yy structure. The initial stress is induced by electro-deformation of the PZT layer in structure.
Tuned refractive index in waveguide structure after applying constant electric field to the PZT layer. The resulting stresses throughout the structure induce a corresponding change in refractive index.
Optimization of the top Pt electrode to get the maximum waveguide effective index change(n ) for the TM00 mode. The colored lines eff show the dependence of n on different top cladding heights with 2 eff m PZT thickness (a) and different PZT layer thickness with 8m top
cladding height(b). The electric field across the PZT layer is 20 V/(m). 0 10 20 30 40 50 60 70 80 90 100
0 0.2 0.4 0.6 0.8 1 1.2 1.4 -4 x 10
Top electrode width (m)
(a)Modification of waveguide n for TM polarizationeff
n eff t_topclad=4m , L =2.85mm t_topclad=8m , L =4.45mm t_topclad=7m , L =4.06mm t_topclad=6m , L =3.65mm t_topclad=5m , L =3.2mm 1,2 1 2
S.N. Hosseini , M.Hoekman , M.A.G Porcel
3 4 5 2 1 1 2
R. Stoffer , R. Dekker , M. Dekkers , P.J.M. Vanderslot , A. Leinse , R.G. Heideman , K.J. Boller
1. LioniX BV, PO Box 456, 7500 AL Enschede, The Netherlands. 2. LPNO, Universiteit Twente, Postbus 217, 7500 AE Enschede, Netherlands. 3. PhoeniX BV, PO Box 545, 7500 AM Enschede, The Netherlands. 4. XiO Photonics BV, PO Box 1254, 7500 BG Enschede, The Netherlands. 5. SolMateS BV, Drienerlolaan 5, building 46, 7522 NB Enschede The Netherlands.
