Proceedings of International Forum for Green Asia 2017
Special issue of Evergreen - Joint Journal of Novel Carbon Resource Sciences & Green Asia Strategy

P-07

Dynamic Mode-Switching by Using Optical Mode Switch
Ryan Imansyah, Luke Himbele, Shota Oe, Haisong Jiang and Kiichi Hamamoto
Interdisciplinary Graduate School of Engineering, Kyushu University
Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan,Abstract
We demonstrated optical mode switch to solve scalability issue in optical switch. We used a designthat similar to Mach-Zehnder interferometer with 3µm of input and output width to provide 1storder mode propagation and get the mode switching instead of intensity modulation. We fabricated
3dB Y-junction with 13 bending angle to get mode switching with a high fabrication tolerance. As
a result, mode switching for 1550nm wavelength with the injection current of 60mA (5.7V) was
successfully achieved with mode crosstalk of approximately -10dB, low wavelength dependency
and polarization independent characteristic. Dynamic mode switching is demonstrated by using
optical mode switch. The switch utilizes phase shift based-on current injection. Less than 60 nsswitching-time for the both 0th-to-1st and 1st-to-0th was confirmed for the first time.
this optical mode switch. The configurationof the optical mode switch is similar to
Mach-Zehnder interferometer, however, thedifference is its width in input and output
waveguide to realize the optical modeswitch than the interference modulation. The
input and output waveguide is designed tobe 3 µm while each arm to be 1.5 µm.
S-bend waveguides are used in the bothY-junctions
torealize
theproper
mode-splitter and mode-combiner with ahigh fabrication tolerance. We employed thetrench pin junction in order to shift the phaseof the light in one of the arms.

1. Introduction
Optical switch is attractive because it
decreases the power consumption of theconventional router by eliminating theoptical-electrical-optical(OEO)
signalexchange [1]. One of the optical switch is the
optical spatial switch. However, the scalability
for high integration has been one critical issue
for this optical spatial switch [2]. Thus, torealize the optical switching we have proposed
optical mode switch to overcome thisscalability issue [3].
In this work, dynamic mode-switching isdemonstrated. At least less than 64 ns
switching time, for the both 0th-to-1st and1st-to-0th, was confirmed.
(a)

(c)
(b)

Figure 2. Dynamic mode-switching result. (a)Injection signal and device status, (b) rise time,and (c) fall time.

(c)Figure 1. Device configuration. (a) Top viewof implemented device, (b) configuration
detail of optical mode switch and (c) MMI
mode filter.

3. Results and Discussion
Figure 2 (a) shows device status from theinjection signal of a 1500 ns with 2 V
peak-to-peak square pulse. The status wasevaluated by monitoring the output power at
the fundamental mode port of MMI filter, as

2. Concept and Design
Concept and Design
Figure 1 (b) shows the schematic view of20

Proceedings of International Forum for Green Asia 2017
Special issue of Evergreen - Joint Journal of Novel Carbon Resource Sciences & Green Asia Strategy

P-07
shown in Fig. 1 (c). When the current is set
to cross-state (approx.60 mA), the device
status shows the lower optical power level,
which corresponds to the first order mode,
while the device status shows higher opticalpower level, which corresponds tofundamental order mode, in the case ofcurrent is set to bar-state. Figure 2 (b) shows
the switching time of 40 ns for 1st-to-0thswitching, while the switching time of 60 ns
for 0th-to-1st switching was observed asshown in Fig. 2 (c). These switching time
can be reduced by the reduction of current
path resistance through the pin trench
structure.
4. Conclusion
In conclusion, we demonstrated the dynamic
optical mode switching for the first time byusing 2x2 optical mode switch. The
measured output power was -28 dB with thecrosstalk of approximately -10 dB. At least
less than 60 ns and 40 ns mode switchingtime, respectively for the both 0th-to-1st and1st-to-0th, was confirmed for the first time.

One way to improve the switching speed isby narrowing the distance between thehighly doped region of p and n. However,there is a trade-off with the carrier
adsorption that will lowering the output
power.

Reference[1] P. Dong, S. Liao, H. Liang, R. Shafiiha, D.
Feng, G. Li, X. Zheng, A. V. Krishnamoorthy
and M. Asghari, “High-speed and broadband
electro-optic silicon switch with submilliwatt
switching power,” Tech. Dig. OFC 2011,OWZ4, (2011)[2] N. Dupuis, “Technologies for Fast, Scalable
Silicon Photonics Switches,” Proc. Photonics
in Switching, p.100 (2015).
[3] R. Imansyah, L. Himbele, H. Jiang and K.
Hamamoto,“FirstDemonstrationofElectrically Controlled Mode Switching,”
Proc. MOC, D3, pp.50-51 (2015).

Email: ryanimansyah@gmail.com

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