实验演示16×16硅基Mach-Zehnder光开关阵列

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"16×16硅基马赫-曾德尔干涉仪开关通过波导微加热器驱动" 这篇研究文章报告了对一个16×16可重构非阻塞光开关网络的实验验证，该网络采用了Benes架构。这个光学开关核心由56个基于2×2马赫-曾德尔干涉器的单元开关组成，每个单元开关都集成了两对波导微加热器。这种集成设计允许通过调整加热器的温度来改变光路的相位，从而实现光信号的路由切换。在"all-cross"（所有交叉）和"all-bar"（所有横杆）两种状态下的平均芯片内插入损耗约为5.2分贝，表明在整个路由路径上的损耗变化控制在1分贝以内，这在大型光开关网络中是相当出色的性能。同时，对于所有开关状态，交叉干扰（crosstalk）均优于-30分贝，这意味着光信号在不同通道间的干扰极小，保证了信号传输的纯净度。开关元件的切换时间约为22微秒，这个速度对于高速光通信系统来说是可接受的，能够支持快速的数据路由和网络配置变化。论文通过40吉比特每秒的正交相位调制信号传输来验证了开关的功能性，进一步证明了该设计在高数据速率光通信中的实用性。马赫-曾德尔干涉仪是一种重要的光学组件，它利用光的干涉原理来实现光路的选择和切换。在硅基光子学中，这种器件因其小型化、高效能和易于集成的特点而受到广泛关注。波导微加热器则为动态控制光路提供了可能，它们可以通过电信号调控，改变波导中的光传播特性，如相位，从而实现光开关的操作。这项工作为大规模光通信网络提供了高效能、低损耗的解决方案，有助于推动未来数据中心和云计算平台的高速光互连技术的发展。其成果不仅限于学术研究，也有望在实际的光通信系统和光网络中得到广泛应用，提升数据传输的速度和可靠性。

16 × 16 silicon Mach–Zehnder interferometer switch

actuated with waveguide microheaters

Shuoyi Zhao, Liangjun Lu, Linjie Zhou,* Dong Li, Zhanzhi Guo, and Jianping Chen

State Key Laboratory of Advanced Optical Communication Systems and Networks, Department of Electronic

Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

*Corresponding author: ljzhou@sjtu.edu.cn

Received July 1, 2016; revised August 29, 2016; accepted August 31, 2016;

posted September 1, 2016 (Doc. ID 269538); published September 23, 2016

We experimentally demonstrate a 16 × 16 reconfigurably nonblocking optical switch fabric using a Benes archi-

tecture. The switch fabric consists of 56 2 × 2 Mach–Zehnder interferometer based elementary switches, with

each integrated with a pair of waveguide microheaters. The average on-chip insertion loss is ∼5.2 dB for both

of the “all-cross” and the “ all-bar” states, with a loss variation of 1 dB over all routing paths. The cross talk

for all switching states is better than −30 dB. The switching time of the switch element is about 22 μs. The switch-

Chinese Laser Press

OCIS codes: (130.0130) Integrated optics; (130.3120) Integrated optics devices; (130.4815) Optical

switching devices.

http://dx.doi.org/10.1364/PRJ.4.000202

1. INTRODUCTION

According to the forecast of Cisco, the annual Internet

Protocol (IP) traffic will surpass the 2 zettabyte threshold

in 2019, and the IP traffic will grow at a compound annual

growth rate of 23% from 2014 to 2019 [1]. The continuous de-

mand for higher data transmission bandwidth requires energy-

efficient switching to support the ever-growing intelligent and

programmable optical networks. A hybrid network architec-

ture will be envisioned in the future to take advantage of both

electrical and optical switching [2]. The electrical switching

can be used for small bursty data flows and data processing

intensive applications while the optical switching is suitable

for larger data flow traffic. Optical switches have the advan-

tages of high switching capacity, low power consumption, and

compact size compared with their electrical counterparts.

Over the past years, a variety of optical switch technologies

have been developed based on micro-electromechanical

system (MEMS) actuators [3,4], silica-based planar lightwave

circuits (PLCs) [5,6], and III–V materials [7,8]. Silicon photon-

ics has been regarded as one of the most promising

technologies for the merits of monolithic integration with

microelectronic drive circuits and potentially low-cost,

large-volume production.

Many N × N thermo-optic (TO) [9–14] and electro-optic

(EO) [15–21] switches have been reported in recent years.

EO switches possess fast switching time (a few nanoseconds)

but have high cross talk and insertion loss due to the electro-

absorption effect associated with the electrorefraction effect

after free-carrier injection. On the contrary, the TO switches

remain low loss, but the switching time is intrinsically limited

to microseconds. In the hybrid network systems, the optical

switches are used to process the slow but large-flow optical

traffic, and therefore the TO switches are preferred for their

low loss and low cross talk. A 32 × 32 TO switch has been

demonstrated [10]. It has a narrow transmission bandwidth

of 1.8 nm for cross talk below −20 dB, and the on-chip inser-

tion loss is 15.8 dB.

In our previous work, we have experimentally demon-

strated two types of 4 × 4 TO switches based on cascaded

multimode interferometers (MMIs) [12,13]. The cross talk

is relatively high due to the imperfect power splitting of

MMIs. In this paper, we present a 16 × 16 reconfigurably non-

blocking silicon TO switch based on 2 × 2 Mach–Zehnder

interferometers (MZIs) actuated with waveguide microheat-

ers. The chip has a footprint of 7 mm × 3.

6 mm. The average

on-chip insertion loss of the 16 × 16 switch is about 5.2 dB, and

the cross talk is below −30 dB in a bandwidth of 10 nm for

all states. Optical transmission of a 40-Gb/s quadrature

phase-shift keying (QPSK) signal verifies the fidelity of the

signal after passing through the switch chip.

2. DEVICE DESIGN AND FABRICATION

The 16 × 16 switch is constructed based on a Benes structure,

as shown in Fig. 1. The Benes architecture is reconfigurably

nonblocking and requires the minimum number of switching

elements to obtain the complete switch states. It possesses the

lowest insertion loss compared to crossbar, switch-and-select,

path-independent insertion-loss (PILOSS), N-stage planar, and

other architectures. A 16 × 16 Benes architecture comprises

56 2 × 2 switch elements. Each routing path goes through

seven stages of switch elements. As each element has two

states, the 16 × 16 switch hence has 2

states in total, among

which 16! states are necessary for the complete mapping. The

inset shows the structure of the switch element. It is com-

posed of two 2 × 2 MMIs with waveguide microheaters inte-

grated in both arms for TO tuning of the silicon refractive

index. The design of the microheater can be found in [17].

The microheater is designed to be 400 μm long in order to

202 Photon. Res. / Vol. 4, No. 5 / October 2016 Zhao et al.

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实验演示16×16硅基Mach-Zehnder光开关阵列

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