Hybrid material integration in silicon photonic integrated circuits

Hybrid integration ofⅢ-Ⅴand ferroelectric materials is being broadly adopted to enhance functionalities in silicon photonic integrated circuits(PICs).Bonding and transfer printing have been the popular approaches for integration of III–V gain media with silicon PICs.Similar approaches are also being considered for ferroelectrics to enable larger RF modulation bandwidths,higher linearity,lower optical loss integrated optical modulators on chip.In this paper,we review existing integration strategies ofⅢ-Ⅴmaterials and present a route towards hybrid integration of bothⅢ-Ⅴand ferroelectrics on the same chip.We show that adiabatic transformation of the optical mode between hybrid ferroelectric and silicon sections enables efficient transfer of optical modal energies for maximum overlap of the optical mode with the ferroelectric media,similar to approaches adopted to maximize optical overlap with the gain section,thereby reducing lasing thresholds for hybridⅢ-Ⅴintegration with silicon PICs.Preliminary designs are presented to enable a foundry compatible hybrid integration route of diverse functionalities on silicon PICs.     

All-optical flip-flop operation of VCSOA

An all-optical flip-flop, the memory of which is based on dispersive bistability in a single vertical cavity semiconductor optical amplifier, is demonstrated experimentally. Flip-flop control is achieved using two mechanisms: cross-phase modulation to set the flip-flop and cross-gain modulation of the holding beam within a remote SOA to reset it. Optical control signals are sub-milliwatt in power and derived from a single 5 ns, 1539 nm initial pulse. Flip-flop operation at 1542 nm is polarisation insensitive to control signals and achieved with an on-off contrast greater than 3 dB.     

Photonic integrated circuits: A technology update

A photonic integrated circuit (PIC) monolithically integrates many optical components, such as lasers, modulators, detectors, attenuators, multiplexers, demultiplexers, and amplifiers, into a single photonic substrate and device. PICs thus provide important benefits for optical transmission systems, including packaging consolidation, increased system density, reduced power consumption, reduction in fiber couplings, and improved reliability.     

The Realization of Large-Scale Photonic Integrated Circuits and the Associated Impact on Fiber-Optic Communication Systems

Large-scale photonic integrated circuits (LS PICs) have been extensively deployed throughout the fiber optic communication network. This paper discusses the properties of the LS PICs, the interaction between them, and what is necessary to create an optical transport system that fully utilizes the properties of the LS PIC     

Photonic integration: Si or InP substrates?

A brief review of recent progress in photonic integrated circuits (PICs) is presented. By examining Moore's Law and the roadmap of conventional electronic ICs, valuable lessons in host material selection for PICs are discussed. Finding a primary host material for integration is necessary and vital to the success of the PIC industry. Initial success has been achieved in both InP-based and silicon-based commercial PICs; however, we believe that cost and performance may select silicon as the primary host material, with the urgency to deploy optical interconnects on Si electronic ICs as one of the main reasons. A recently introduced hybrid silicon evanescent platform and devices and silicon/germanium APDs are reviewed as examples to understand the viability of silicon PICs and lead to an understanding of a possible roadmap to next generation large-scale PICs.     

Digital optical networks using photonic integrated circuits (PICs) address the challenges of reconfigurable optical networks

To reduce costs and simplify operations, carriers are deploying flexible optical networks that can be easily reconfigured and managed remotely. This article provides an overview of typical all-optical reconfigurable optical add/drop multiplexer (ROADM) systems and their associated network issues. We describe a novel digital optical network architecture based on digital ROADM systems, which use photonic integrated circuits (PICs) to overcome many of these issues. Digital ROADM systems use monolithic PICs to integrate over 60 discrete optical components, including lasers, modulators and detectors, into a single pair of optical components, allowing cost-effective optical-electrical-optical conversion at every node. This also allows key functions such as service reconfiguration, add/drop and protection to be implemented in the digital domain, and enables de-coupling of service provisioning from optical link engineering, termed bandwidth virtualization. Finally, key deployment, reliability and operational metrics for PIC-based digital ROADM systems are presented.     

Thermal and Optical Characterization of Photonic Integrated Circuits by Thermoreflectance Microscopy

We report high resolution, non-invasive, thermal and optical characterization of semiconductor optical amplifiers (SOAs) and SOA-based photonic integrated circuits (PICs) using thermoreflectance microscopy. Chip-scale temperature imaging of SOAs and PICs, along with an energy balance model, are used to calculate the optical power distribution within and between SOAs to determine optical gain, fiber coupling loss, and passive component loss under normal device operating conditions. This technique is demonstrated to map optical power in SOA-based Mach–Zehnder interferometer (SOA-MZI) PICs, with close agreement with photocurrent and fiber-coupled measurements. The use of amplified spontaneous emission (ASE) for fiber-free characterization of the PICs is also shown, enabling non-invasive, wafer-scale testing prior to packaging.      

高速光器件的光集成及光电集成

本文介绍了高速激光器的现状，并综述了高速激光器的光集成和接收机的光电集成。最后，讨论了光集成和光电集居技术及今后的发展。     

半导体光集成电路

半导体光集成电路(PIC)是光电子集成电路(OEIC)的一个分支,它侧重于光学互连的导波光电子器件的单片集成。由于Ⅲ-Ⅴ族材料外延晶体生长和相关工艺技术方面的进步,这一研究领域最近取得明显进展。本文讨论了集成有源和无源光波导的某些必要技术,并介绍了几种典型器件。     

Monolithic integration of multiple quantum well DFB lasers and electroabsorption modulators

Advanced fibre optics telecommunication systems rely on high performance components amongst which photonic integrated circuits (PICs) play a major role. In particular, there has been a growing need for low chirp optical sources, such as externally modulated distributed feedback (DFB) lasers. In this paper, the various monolithic integration schemes of multiple quantum well DFB lasers and electro-absorption modulators are reviewed and typical applications of these devices are briefly presented.     

InP基环形波导激光器的研究与进展

光子集成作为未来全光网络发展的必然趋势,是实现高速光通信的重要解决方案。正如硅基集成电路的发展历程一样,找到一种类似晶体管的基本集成单元,并实现光子集成的大多数功能是目前光子集成技术中最迫切的问题。近年来,由于半导体环形谐振器的功能多样性和可集成性,使其最有可能成为光子集成的基本单元,因而成为集成光子学、光通信和光信息处理领域的研究热点。文章在介绍半导体环形激光器工作原理和基本特性的基础上,总结了InP基环形波导激光器在集成光源及光信息处理方面的应用和最新进展。     

Effective Pigtailing Method for Fiber Arrays to InP-Based Photonic Integrated Circuits

A reliable technology for interfacing signals in both the optical and electrical domain that provides the possibility of precise control of the thermal optical chip properties is an essential requirement to utilize photonic integrated circuits in system-related areas. Hence, a practical assembly method is developed here to connect fiber arrays to a wide range of different kinds of advanced Indium Phosphide-based photonic integrated circuits. The essence of this procedure is a well-controlled step-by-step pigtailing approach whereby any misalignments during the assembly process can be compensated for using laser supported adjustment. The pigtailing process of two different multiport photonic integrated circuits is described. The circuits include an integrated two-state multiwavelength laser chip, operating at 25 $^{circ}$C, and a coupled Mach–Zehnder interferometer chip, operating at 10 $^{circ}$ C. Both devices function as a 1 bit optical memory element with optical set and reset functions. Successful alignment compensation on the order of 0.1 ${-}3 mu$m is demonstrated. Subsequently, the subassemblies are fixed unambiguously on thermo-electric coolers in a package with a clamp method to reduce internal stress in the subassembly. Consequently, the mechanical alignment stability of both devices are proven to be smaller than 25 nm/ $^{circ}$C, as measured in a temperature range from 10 $^{circ}$C to 30 $^{circ}$C.      

Dynamics of InAs/GaAs quantum dot lasers epitaxially grown on Ge or Si substrate

Growing semiconductor laser sources on silicon is a crucial but challenging technology for developing photonic integrated circuits(PICs).InAs/GaAs quantum dot(Qdot)lasers have successfully circumvented the mismatch problem betweenⅢ–Ⅴmaterials and Ge or Si,and have demonstrated efficient laser emission.In this paper,we review dynamical characteristics of Qdot lasers epitaxially grown on Ge or Si,in comparison with those of Qdot lasers on native GaAs substrate.We discuss properties of linewidth broadening factor,laser noise and its sensitivity to optical feedback,intensity modulation,as well as mode locking operation.The investigation of these dynamical characteristics is beneficial for guiding the design of PICs in optical communications and optical computations.     

Single-mode Nd3+-doped graded-index polymer waveguideamplifier

The first graded index (GRIN) polymer waveguide amplifier working at 1.06 μm wavelength has been realized, using a Nd³⁺: photolime gel material combination. Throughput intensity of 3.8 mW at 1.06 μm, corresponding to 8.5 dB gain, was observed when employing a 40 mW pumping laser beam operating at 790 nm. The gain medium is a 2.2 cm waveguide active region with Nd³⁺ concentration of 1.03×10²⁰/cm³. The GRIN characteristic of the photolime gel thin film provides a universal means for implementing polymer-based photonic integrated circuits (PICs) on any substrate of interest     

All-optical flip-flop multimode interference bistable laser diode

All-optical flip-flop operation of multimode interference bistable laser diodes (MMI-BLDs) was experimentally demonstrated for the first time. The MMI-BLD was prepared with a conventional ridge waveguide laser diode fabrication procedure, suitable for photonic integrated circuits. Bistable switching via two-mode bistability was obtained with approximately 0-dBm input powers due to cross-gain saturation and the saturable absorbers. Bit-length conversion was successfully obtained with noninverted and inverted outputs. This device will be useful in future photonic systems requiring all-optical latching functions such as optical memory, self-routing, and further optical signal processing.     

Multiplexed polymer-based chirped grating lenses working at 632.8nm wavelength

A multiplexed waveguide hologram containing two off-axis chirped grating lenses working at 632.8 nm was demonstrated on a glass substrate. Focal lengths of 35 and 37 mm were experimentally confirmed. The nature of phase modulation of the holographic medium allows the formation of multiplexed waveguide lenses on the same waveguide emulsion area. The graded index (GRIN) characteristic of the guiding medium allows the formation of polymer-based photonic devices on any substrate of interest which greatly enhances the transferability of polymer based photonic integrated circuits (PICs) to various optoelectronic circuits     

Packaged and hybrid integrated all-optical flip-flop memory

A fully-packaged hybrid-integrated all-optical flip-flop, where InP-based semiconductor optical amplifiers are assembled onto a planar silica waveguide board, is demonstrated. It is shown experimentally that the flip-flop can dynamically toggle between its two states by injecting 150 ps optical pulses with 6 dBm peak power via its set and reset port     

Integration of InGaAsP/InP optoelectronic bistable switches with afunction of optical erasing

An OE-PPM (optically erasable photonic parallel memory) that is an array of 10×10 optoelectronic bistable switches with an optical set and reset function has been fabricated successfully, and set and reset operation with light signals has been demonstrated. The switch consists of a heterojunction phototransistor (HPT) and a light-emitting diode (LED), and the reset operation is performed by an additional reset HPT. The minimum reset power is 1.6 μW at a bias voltage of 0.9 V, and the set power and the dissipation current at the same bias condition are 3.4 μW and 200 μA, respectively. These values are thought to be low enough for array operation. A light pulse with a width of 10 ns was able to set or reset the switch, though the set and reset powers were increased to 547 and 406 μW, respectively. The dominant factor that limits the speed of set and reset operation is thought to be the response time of the HPT     

Laterally Coupled DFB Lasers for One-Step Growth Photonic Integrated Circuits in InP

Design and characterization of a transmitter building block for one-step growth photonic integration, featuring a 1310 - nm laterally coupled distributed-feedback laser with a front-side passive optical waveguide and a back-side optical power monitor, are presented. Formed on a semi-insulating Fe : InP substrate and processed by means of a stepper optical lithography, the device perfectly suits the multiguide vertical integration-a newly developed one-step growth photonic integrated technique in InP.     

小型化高集成宽带光收发组件

当前分立光子器件的体积和成本严重制约着微波光子技术在雷达系统中的应用。受限于当前的集成能力和材料体系,微波光子单片集成芯片短时间内难以实现工程应用。为满足雷达等应用场景对高集成微波光子器件的迫切需要,研制了一种新型小型化高集成光收发组件。该组件采用光电异构集成封装技术,将MZM调制器芯片、微波芯片、探测器芯片以及光环形器、波分复用器进行高度集成,单模块体积仅为85 mm×35 mm×10 mm,与传统MZM调制器体积相当。实验结果表明,其性能可与传统分立元器件相媲美。在6~18 GHz范围内,组件能够实现±1.5 dB的平坦度,上行能够实现18 dB以上的增益,下行能够实现?1 dB以上的增益,且链路噪声系数小于30 dB,平面化、小型化设计使其能够应用于相控阵雷达、电子战等多种应用场景,具有广阔的应用前景。