IEC TR 63072-1:2017

Photonic integrated circuits - Part 1: Introduction and roadmap for standardization

IEC TR 63072-1:2017(E) which is a Technical Report, provides an introduction to photonic integrated circuits (PICs) and describes a roadmap for the standardization of PIC technology over the next decade.

General Information

• Status: Published
• Publication Date: 10-May-2017
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 33.180.99 - Other fibre optic equipment
• Technical Committee: SC 86C - Fibre optic systems, sensing and active devices
• Current Stage: PPUB - Publication issued
• Start Date: 11-May-2017
• Completion Date: 09-May-2017

Overview

IEC TR 63072-1:2017 is a Technical Report published by the International Electrotechnical Commission (IEC). Titled "Photonic Integrated Circuits – Part 1: Introduction and Roadmap for Standardization", this document offers a comprehensive introduction to photonic integrated circuits (PICs) and outlines the roadmap towards the standardization of PIC technology over the coming decade.

Photonic integrated circuits are revolutionizing the fields of telecommunications, data centers, sensing, and emerging areas like quantum computing. This standard serves as a foundational resource for stakeholders seeking to understand the current landscape and future direction of PIC development and standardization.

---

Key Topics

• Definition and Scope of PICs
  Introduction to PICs, including their core components, operational principles, and scope of capabilities.

• PIC Material Platforms
  Overview of common materials used, such as silicon, indium phosphide (InP), and silicon nitride, highlighting their respective strengths and limitations.

• Manufacturing and Market Landscape
  Discussion on global manufacturing capacities, market growth projections, and notable organizations driving the field.

• Integration Techniques
  Insights into heterogeneous and homogeneous integration, leveraging existing CMOS infrastructure for embedded photonics.

• Global R&D Initiatives
  Summary of government investments and strategic research activities in key regions, notably North America, Europe, and Japan.

• Standardization Roadmap
  Identification of emerging needs for uniformity in interfaces, packaging, testing, and design workflows.

---

Applications

Photonic integrated circuits are essential components across several fast-growing industries, offering high performance, miniaturization, and energy efficiency. Practical applications of PICs include:

• Optical Fiber Communications

  • Support for high-speed data transmission
  • Dense wavelength division multiplexing (DWDM) systems for expanding network capacity

• Data Centers and Cloud Computing

  • Energy- and cost-efficient transceivers
  • Scalability for modern data traffic demands

• Optical Sensors

  • Highly sensitive measurement platforms for medical diagnostics, aerospace monitoring, and industrial process control

• Quantum Technologies

  • Building blocks for quantum computing and secure communication systems

• Automotive and Defense

  • Advanced LIDAR systems and robust, miniaturized photonic sensors for safer vehicles and precise navigation

By standardizing PIC components and processes, the industry can ensure interoperability, drive down costs, and foster innovation across these sectors.

---

Related Standards

For professionals engaged with photonic and optoelectronic technologies, the following standards complement IEC TR 63072-1:

• IEC 60793 / IEC 60794

  • Standards for optical fibers and cables, foundational for PICs used in communication networks

• IEC 62148

  • Outlines module and package interfaces for optical devices, aiding in the alignment of PIC packaging

• IEC 61290

  • Describes measurement techniques for optical amplifiers, relevant for PIC testing

• IEC 60825

  • Addresses safety standards for laser products, pertinent when integrating laser sources into PICs

• IEEE and ISO optical component standards

  • Additional references for system-level compatibility and terminology

---

Keywords: Photonic Integrated Circuits, IEC TR 63072-1, PIC standardization, silicon photonics, indium phosphide, optical communications, PIC packaging, PIC manufacturing, quantum computing, optical sensors, global PIC market, photonics standards.

---

By following the roadmap and concepts outlined in IEC TR 63072-1:2017, stakeholders can better navigate the evolving field of photonic integrated circuits, ensure alignment with industry trends, and contribute to the growth and standardization of next-generation photonic technologies.

Standards Content (Sample)

IEC TR 63072-1 ®
Edition 1.0 2017-05
TECHNICAL
REPORT
colour
inside
Photonic integrated circuits –
Part 1: Introduction and roadmap for standardization

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC
copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or
your local IEC member National Committee for further information.

IEC Central Office Tel.: [phone]
3, rue de Varembé Fax: [phone]
CH-1211 Geneva 20 [e-mail]
Switzerland www.iec.ch
About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.

IEC Catalogue - webstore.iec.ch/catalogue Electropedia - www.electropedia.org
The stand-alone application for consulting the entire The world's leading online dictionary of electronic and
bibliographical information on IEC International Standards, electrical terms containing 20 000 terms and definitions in
Technical Specifications, Technical Reports and other English and French, with equivalent terms in 16 additional
documents. Available for PC, Mac OS, Android Tablets and languages. Also known as the International Electrotechnical
iPad. Vocabulary (IEV) online.

IEC publications search - www.iec.ch/searchpub IEC Glossary - std.iec.ch/glossary
The advanced search enables to find IEC publications by a 65 000 electrotechnical terminology entries in English and
variety of criteria (reference number, text, technical French extracted from the Terms and Definitions clause of
committee,…). It also gives information on projects, replaced IEC publications issued since 2002. Some entries have been
and withdrawn publications. collected from earlier publications of IEC TC 37, 77, 86 and

CISPR.
IEC Just Published - webstore.iec.ch/justpublished

Stay up to date on all new IEC publications. Just Published IEC Customer Service Centre - webstore.iec.ch/csc
details all new publications released. Available online and If you wish to give us your feedback on this publication or
also once a month by email. need further assistance, please contact the Customer Service
Centre: [e-mail].
IEC TR 63072-1 ®
Edition 1.0 2017-05
TECHNICAL
REPORT
colour
inside
Photonic integrated circuits –

Part 1: Introduction and roadmap for standardization

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.180.99 ISBN 978-2-8322-4279-7

– 2 – IEC TR 63072-1:2017  IEC 2017
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Photonic integrated circuit (PIC) . 9
4.1 Overview. 9
4.2 PIC families . 11
4.2.1 General . 11
4.2.2 Silicon photonics . 12
4.2.3 III-V photonics . 12
4.2.4 Silica and silicon nitride PICs. 12
4.3 Manufacturing capabilities. 13
4.4 Global market . 13
4.5 Global government investment in PIC research and development . 13
4.5.1 General . 13
4.5.2 United States of America . 13
4.5.3 Europe. 13
4.5.4 Japan . 13
5 Silicon photonics . 14
5.1 Overview. 14
5.2 Integration schemes . 14
5.2.1 General . 14
5.2.2 Heterogeneous integration . 15
5.2.3 Homogenous integration . 15
5.3 Non-linear behaviour . 15
6 III-V photonics . 15
6.1 Indium phosphide (InP) photonics . 15
7 PIC transceiver – A simple example . 17
7.1 Overview. 17
7.2 Transmitter section . 17
7.3 Receiver section . 18
8 Optical sources . 19
8.1 Overview. 19
8.2 Advances in III-V integration onto silicon PICs . 19
8.3 Vertical cavity surface emitting lasers (VCSELs) . 20
9 Optical receivers. 20
10 Modulators . 21
10.1 Overview. 21
10.2 Common modulator structures . 21
10.3 Plasma dispersion effect . 22
10.4 Plasmonics . 23
10.5 Silicon organic hybrid . 23
11 Switches . 24
11.1 Overview. 24
11.2 Mach-Zehnder interferometers (MZI) . 24
11.3 Micro-ring resonator (MRR) . 24

11.4 Double-ring assisted MZI (DR-MZI) . 25
12 3D integration . 25
12.1 Optochip . 25
12.2 Through-silicon-vias (TSVs) . 25
12.3 Hybrid integration process example . 26
12.4 Flip-chip bonding . 26
12.5 State of the art in 3D research and development . 27
13 Commercial state of the art . 27
13.1 Overview. 27
13.2 Luxtera . 27
13.3 Intel . 28
13.4 Mellanox . 28
13.5 Oracle . 29
13.6 IBM . 29
13.7 Photonics Electronics Technology Research Association (PETRA) . 29
14 PIC coupling interfaces . 30
14.1 Overview. 30
14.2 Grating coupler . 30
14.3 Adiabatic coupling . 33
14.4 Butt coupling . 35
14.5 Orthogonal chip-to-fibre coupling . 35
15 Electrical interface . 36
16 Packaging . 37
17 Standardization roadmap . 37
Bibliography . 39

Figure 1 – Examples of PICs [1] . 11
Figure 2 – Optical beam forming network fabricated in TriPleX (silicon nitride). 12
Figure 3 – Typical silicon waveguides [6] . 14
Figure 4 – Heterogeneous integration by flip chip and copper pillars . 15
Figure 5 – Indium phosphide PIC with many structures, including AWG . 16
Figure 6 – Combined InP and TriPleX microwave photonic beam-forming network . 17
Figure 7 – Schematic of four channel PIC transceiver by Luxtera [6] . 18
Figure 8 – Schematic view of 3D assembly of PIC + EIC electro-optical assembly [6] . 20
Figure 9 – Example of Ge-on-Si photodetector formed by germanium selective epitaxy [6] . 21
Figure 10 – High speed PN modulator [6] . 22
Figure 11 – PETRA optical I/O core chip modulation scheme . 23
Figure 12 – Silicon organic hybrid . 24
Figure 13 – 4 x 4 switching matrix PIC attached to PCB with wire bonds on the EU
FP7 PhoxTroT project . 25
Figure 14 – EU FP7 project PhoxTroT 3D integrated optochip concept . 26
Figure 15 – LIFT principle . 27
Figure 16 – PETRA optical I/O core performance at 25 Gb/s . 29
Figure 17 – Examples of vertical grating couplers [6] . 31
Figure 18 – Coupling efficiency of single polarization grating coupler (SPGC) at 1 310
nm and 1 490 nm [91] . 32

– 4 – IEC TR 63072-1:2017  IEC 2017
Figure 19 – Composite coupling interfaces on PETRA optical I/O core . 32
Figure 20 – Assembly for adiabatic optical coupling between Si photonics chip and SM
polymer waveguide . 33
Figure 21 – Flip-chipped silicon photonic chip onto polymer waveguide substrate using
adiabatic coupling . 34
Figure 22 – Bidirectional optical coupling between SOI waveguides and single polymer
waveguides . 35
Figure 23 – Design of the mirror plug assembly . 36
Figure 24 – Typical operative framework of silicon-photonics modules . 37
Figure 25 – PIC standardization roadmap . 38

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
PHOTONIC INTEGRATED CIRCUITS –

Part 1: Introduction and roadmap for standardization

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 62072-1, which is a Technical Report, has been prepared by subcommittee 86C: Fibre
optic systems and active devices, of IEC technical committee 86: Fibre optics.
The text of this Technical Report is based on the following documents:
Enquiry draft Report on voting
86C/1428/DTR 86C/1441/RVDTR
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.

– 6 – IEC TR 63072-1:2017  IEC 2017
This document has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 63072-1 series, published under the general title Photonic
integrated circuits, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to
the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
PHOTONIC INTEGRATED CIRCUITS –

Part 1: Introduction and roadmap for standardization

1 Scope
This part of IEC 63072, which is a Technical Report, provides an introduction to photonic
integrated circuits (PICs) and describes a roadmap for the standardization of PIC technology
over the next decade.
NOTE The trademarks and trade names mentioned in this document are given for the convenience of users of this
document; this does not constitute an endorsement by IEC of these companies.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
photonic integrated circuit
PIC
integrated circuit that contains optical structures to guide and process optical signals
3.2
III-V
three-five
compound semiconductor formed of materials from the third and fifth column of the periodic
table
EXAMPLE 1 Indium phosphide
EXAMPLE 2 Gallium arsenide
3.3
through-silicon-via
TSV
metallised hole (via) through a silicon wafer enabling electrical conductivity from one surface
of the silicon to the other
3.4
silicon photonics
structure or system of structures fabricated into a silicon wafer to guide light and enable
passive and active optical processes to be carried out at the integrated circuit level

– 8 – IEC TR 63072-1:2017  IEC 2017
3.5
silicon-on-insulator
SOI
structure or system of structures fabricated into a silicon wafer to guide light and enable
passive and active optical processes to be carried out at the integrated circuit level
3.6
vertical cavity surface emitting laser
VCSEL
semiconductor laser diode with direction of laser emission perpendicular to top surface
3.7
Mach-Zehnder interferometer
MZI
waveguide structure whereby an incident optical signal is split into two paths and allowed to
recombine into an output signal and on which the phase variance between the two
recombined signals can be manipulated to allow modulation of the output signal or switching
between two or more input and output signals
3.8
ring resonator
closed optical path in which the optical radiation circulates in an optical loop in the same
direction
Note 1 to entry: Standing waves are possible to exist at particular wavelengths.
3.9
micro-ring resonator
MRR
closed ring resonator waveguide structure on a PIC
Note 1 to entry: When located near a waveguide, the MRR will selectively couple out of the waveguide optical
radiation only at the wavelengths λ , which satisfy the following resonance condition: MRR optical path length =
m
2πn = m λ , where n is the effective refractive index of the MRR waveguide and m is a positive integer.
eff m eff
3.10
resonator finesse
F
quantity describing the sharpness of a resonant peak relative to the free spectral range of the
resonator, obtained by dividing free spectral range (FSR) of a resonator by full width half
maximum (FWHM) of a resonant peak
3.11
quality factor of a ring resonator
resonator finesse multiplied by the mode number m, where m = 2πn λ and where n is the
eff/ m eff
effective refractive index of the ring resonator and λ is the resonant wavelength
m
3.12
large-scale integration
LSI
process of integrating thousands of transistors onto a single semiconductor chip
3.13
buried oxide
BOX
silicon dioxide (SiO ) layer buried in silicon wafers to form silicon-on-insulator assemblies
Note 1 to entry: BOX layer is typically buried at less than 100 nm to several micrometers beneath the wafer
surface depending on application. BOX layer thickness typically ranges from 40 nm to 100 nm.

3.14
grating coupler
GC
periodic grating structure on the surface of a PIC, which redirects light propagating in a
waveguide in the PIC out through the surface of the PIC, typically at a small angle normal to
the PIC surface
Note 1 to entry: This is the preferred method of coupling light into and from a PIC and typically uses a single-
mode fibre or single-mode fibre array with an 8° angled interface. Therefore grating couplers are usually designed
to redirect light into and out of the PIC at an angle of 8° normal to the PIC surface.
3.15
single polarization grating coupler
SPGC
grating coupler designed to couple light of one linear polarization to and from a waveguide in
the PIC
3.16
polarization splitting grating coupler
PSGC
grating coupler designed to split the light incident on the PIC into two orthogonal linear
polarizations, which are conveyed along two separate corresponding waveguides in the PIC
3.17
laser induced forward transfer
LIFT
direct-writing technique allowing the deposition of tiny amounts of material from a donor thin
film through the action of a pulsed laser beam
3.18
complementary metal oxide semiconductor
CMOS
technology for constructing low power integrated circuits typically used in microprocessors,
microcontrollers, static RAM, and other digital logic circuits
3.19
high speed phase modulator
HSPM
device allowing the phase of an optical signal to be rapidly varied
Note 1 to entry: One example of a HSPM is a PN junction on one of the waveguide branches of a MZI in a PIC,
which causes a change in refractive index in response to the density in charge carriers passed through it.
4 Photonic integrated circuit (PIC)
4.1 Overview
A PIC is an integrated circuit on which operations can be carried out on light conveyed
through it. One could think of a PIC as a miniature optical train, i.e. a sequence or collection
of elements or structures, which perform an operation on one or more incident light beams.
These operations may include modulation, wavelength dependent and independent switching,
wavelength multiplexing/demultiplexing, power splitting, filtering, amplification, light
generation (lasers) and light detection (detectors). Depending on the available chip size,
element size and layout efficiency of optical elements and structures, a PIC can incorporate
functions of varying complexity.
PICs operate on information signals imposed on optical wavelengths typically within the
infrared 850 nm to 1 650 nm portions of the electro-magnetic spectrum reserved for fibre optic
communication.
– 10 – IEC TR 63072-1:2017  IEC 2017
PICs can accommodate huge bandwidth densities, for example high data rates of information
conveyed along tiny channels, which can be very densely arranged at the chip level. For this
reason, PIC products are primarily deployed in the optical fibre communications market.
Optical sensors, however, represent a promising emerging application field for PICs, in which
they can be used in the medical, aerospace, energy, automotive and defence sectors.
PICs are also widely anticipated to play a key role in the future commercialisation of quantum
computers.
Figure 1 shows some examples of PICs of varying complexity and functionality.
1 × 8 AWG
1 mm
IEC
a) Wavelength-division multiplexing (WDM) receiver consisting of
an array waveguide (AWG) integrated with an 8 detector diode
λ
λ
2 × 8 AWGs
λ
λ
IEC
b) 4-channel 2 × 2 WDM cross-connect integrating 2 AWGs with 16 Mach-Zehnder
interferometer switches in dilated configuration (66 components in total)
1 × 5 AWG
1 × 8 AWG
8×
IEC
c) 40-channel WDM monitor chip integrating 9 AWGs and 40 detector diodes
Detector
Detector
array
array
IEC
d) 8 × 8 channel wavelength router, integrating 8 wavelength converter circuits
with an 8 × 8 AWG, with over 175 components
Wavelength converter array Arrayed-waveguide grating router
4,25 mm
14,5 mm
Out
a)
Preamplifier Booster MZI
Delay line Phase shifter
SOAs SOAs SOAs
SG DRR
Power Attenuators Absorber Power MZI Switch Power
monitors monitors monitors
b)
IEC
e) Detail of wavelength converter section
SOURCE Institute of Physics
Figure 1 – Examples of PICs [1]
4.2 PIC families
4.2.1 General
The fabrication techniques for PICs are similar to those used in electronic integrated circuits,
in which photolithography is used to pattern semiconductor wafers for etching and material
deposition.
Unlike electronic integration where silicon is the dominant material, PICs can be fabricated
from a variety of semiconductor materials including silicon, indium phosphide (InP) and
gallium arsenide (GaAs), and different material systems, including electro-optic crystals such
as lithium niobate, silica-on-silicon and silicon-on-insulator (SOI).
Different materials provide different advantages and limitations depending on the functions to
be carried out.
__________
Figures in square brackets refer to the Bibliography.
In
– 12 – IEC TR 63072-1:2017  IEC 2017
4.2.2 Silicon photonics
Silicon PICs enable direct co-integration of the photonics with transistor based electronics;
however, as an indirect bandgap material, silicon PICs will typically require separate elements
for light generation and detection. Although it was shown in 2005 that silicon can be used to
generate laser light via the Raman effect, such lasers would need to be optically driven rather
than electrically driven, which would require an additional optical pump laser source [2].
4.2.3 III-V photonics
PICs based on so called direct bandgap materials, such as indium phosphide or gallium
arsenide, do allow the direct integration of light sources and detectors on the same integrated
circuit; however, the foundry infrastructure is much more limited when compared to silicon
wafers, leading to III-V PICs being typically restricted to low volume, high cost applications.
4.2.4 Silica and silicon nitride PICs
Silica (silicon dioxide) based PICs have very desirable properties for passive photonic circuits
such as arrayed waveguide gratings (AWGs) due to their comparatively low losses and low
thermal sensitivity.
Silicon nitride (Si N ) based PICs are also becoming a leading material candidate for PICs in
3 4
the datacom space, mainly due to the lower optical losses introduced and the inherent
complementary metal oxide semiconductor (CMOS) compatibility with the electronics
fabrication processes (see Figure 2).
IEC
SOURCE Photo courtesy of SATRAX B.V., www.satrax.nl
Figure 2 – Optical beam forming network fabricated in TriPleX (silicon nitride)
Currently, the two most commercially utilised material platforms for PICs are based on silicon
and indium phosphide.
4.3 Manufacturing capabilities
As of 2016, there were only a handful of organisations that could directly manufacture PICs.
These included STMicroelectronics (France-Italy), Intel (US), and AMS (Austria).
Given the long turn-around for PIC wafer fabrication, the concept of multi project wafers was
introduced by which a variety of different PIC designs from different organisations (usually
small to medium enterprises) could be incorporated onto a single wafer, allowing a variety of
different designs to be fabricated at once. Access to PIC fabrication by small to medium
enterprises has been made possible through so-called multi-project wafer platforms, including
JEPPIX (http://www.jeppix.eu/) for III-V photonics, EPIXFAB (http://www.epixfab.eu/) for
silicon photonics, and TRIPLEX ("http://www.lionixbv.nl/triplex-integrated-optics) for silicon
nitride photonics.
4.4 Global market
As of 2013, North America was the leader in the PIC market with 49 % market share; however,
it is estimated that Asia-Pacific (APAC) will emerge as the market leader by 2022, growing at
a compound annual growth rate (CAGR) of 35,9 % from 2012 to 2022.
The PIC market is expected to yield revenue growth from $150,4 million in 2012 to $1 547,6
million by 2022, at an estimated CAGR of 26,3 % from 2012 to 2022 [3].
As of 2015, some of the leading global organisations selling PIC products are Infinera
Corporation (USA), NeoPhotonics Corporation (USA), Luxtera (USA), Mellanox (Israel) and
OneChip Photonics (Canada).
4.5 Global government investment in PIC research and development
4.5.1 General
In addition to large scale research and development on PIC technologies, as of 2016, there
has been renewed global government level investment into PIC development, which is seen
as a key enabling technology.
4.5.2 United States of America
The importance of developing an integrated photonic eco-system was underscored by the
launch in 2016 of the American Institute of Manufacturing Integrated Photonics (AIM), a
public-private partnership providing over $610m worth of funding
(http://www.aimphotonics.com/).
4.5.3 Europe
As of 2016, the European Commission Horizon2020 framework programme has provided and
was expected to continue to provide substantial funding towards integrated photonics
technologies between 2014 and 2020 of a similar order to that of the United States AIM
initiative.
4.5.4 Japan
Photonics Electronics Technology Research Association (PETRA) is an incorporated
technology research association, established on August 24, 2009. The organization is
approved by METI (Ministry of Economy, Trade and Industry) under the Japanese Act on an
Incorporated Research and Development Partnership. PETRA carries on national research
and developments projects on leading-edge photonics and electronics converged devices and
systems in the information and communication technology area, where photonics technology
and electronics technology are mutually incorporated.

– 14 – IEC TR 63072-1:2017  IEC 2017
5 Silicon photonics
5.1 Overview
Silicon photonics is the study and application of PICs, which use silicon as an optical medium
and offers the promise of high volume, low cost PIC fabrication in the near future, as it
leverages currently available CMOS manufacturing infrastructures. This allows silicon PICs to
be manufactured using existing semiconductor fabrication techniques.
The silicon-on-insulator (SOI) configuration, whereby a layer of silicon is bounded by a layer
of silica, is the preferred choice for passive PIC structures, including multi-mode interference
(MMI) structures, directional couplers, mode converters, in-plane couplers, out-of-plane
(angled or vertical) grating couplers, splitters, optical filters polarization rotators and
polarization beam splitter/combiners [4], [5].
Figure 3 shows an example of single-mode silicon waveguides fabricated on SOI substrates.
a)
0,32 µm
80 nm
100 nm
b)
IEC
SOURCE IEEE
Key
(a) λ = 1,31 µm single mode waveguide cross-section
(b) Top view scanning electron microscope image of semi-dense 80 nm trenches
Figure 3 – Typical silicon waveguides [6]
5.2 Integration schemes
5.2.1 General
Integration of optical and electronic functionality on a PIC can be achieved through either
heterogeneous integration, where separate optical and electronic chips are assembled onto
each other [7], or by homogenous integration [8], [9], where optical and electronic circuits are
built on the same chip [10].
166 nm
306 nm
5.2.2 Heterogeneous integration
As silicon is also the substrate used for most electronic integrated circuits (EICs),
heterogeneous (or hybrid) integration of separate EICs and PICs provides a lower risk
pathway to developing "active" PICs that combine complex electronic functionalities such as
transimpedance amplifiers and modulators with photonic structures and elements.
The main advantage of heterogeneous integration is that the EICs and PICs are separately
fabricated to achieve their respective optimised performances before bringing both elements
together [11], while with homogenous fabrication, there is an inherent compromise on
fabrication and performance. The disadvantage of heterogeneous integration is, however, a
more complicated packaging and assembly process, limited density, more power dissipation
and worse RF performance. An example of heterogeneous (or hybrid) integration based on
flip-chip connection through copper pillars is shown in Figure 4.
Underfill
Fiber Cu-Pi
EIC
Bondwire
20 µm
PIC
40 µm
(Not to scale)
Board/package
IEC
SOURCE University of Pavia
Figure 4 – Heterogeneous integration by flip chip and copper pillars
5.2.3 Homogenous integration
Homogenous (or monolithic) integration allows packaging and assembly to be simplified, as
now electronic and optical circuits are co-fabricated on the same chip. Homogenously
integrated solutions typically rely either on SOI wafers [9], [11], [12], or on bulk silicon [8].
5.3 Non-linear behaviour
The propagation of light through silicon devices is governed by a range of nonlinear optical
phenomena including the Kerr effect, the Raman effect, two photon absorption, and
interactions between photons and free charge carriers. The presence of nonlinearity is of
fundamental importance, as it enables light to interact with light, thus permitting applications
such as wavelength conversion and all-optical signal routing in addition to the passive
transmission of light.
6 III-V photonics
6.1 Indium phosphide (InP) photonics
Unlike silicon, indium phosphide (InP) is a direct bandgap material and thus allows for the co-
integration of various optically active and passive functions on the same chip, including
optical sources, amplifiers (gain elements), waveguides, modulators, and receivers.
Early examples of InP PICs were distributed Bragg reflector (DBR) lasers, consisting of two
independently controlled elements, namely a gain chip and a DBR mirror section.

– 16 – IEC TR 63072-1:2017  IEC 2017
Most modern monolithic tuneable lasers, externally modulated lasers (EMLs), and integrated
receivers are based on InP PICs.
The most notable global academic centres of excellence for InP PIC research are the
University of California at Santa Barbara, USA, and the Technology University of Eindhoven in
the Netherlands.
Although III-V based photonics is widely accepted as the most mature integration technology
due to its capability to deliver high-performance active devices, it still remains inherently a low
volume, high margin technology due to the relatively low availability III-V wafer foundries
when compared to CMOS infrastructures and processes.
Figure 5 and Figure 6 are examples of indium phosphide PICs.
IEC
SOURCE Heinrich Hertz Institute
Figure 5 – Indium phosphide PIC with many structures, including AWG

IEC
SOURCE Photo courtesy of SATRAX B.V., www.satrax.nl
Figure 6 – Combined InP and TriPleX microwave photonic beam-forming network
7 PIC transceiver – A simple example
7.1 Overview
One of the simplest PIC functions is a transceiver PIC, which, on the transmitter section of the
PIC, takes continuous wave light from an optical source (either monolithically integrated,
heterogeneously assembled or external) and passes it along a waveguide to a modulator,
which is typically driven by an electronic signal through a variety of possible modulation
mechanisms described below. The modulated light is then further conveyed along an
integrated waveguide to an external coupler, which couples the light out of the PIC, typically
to a single-mode optical fibre. On the receiver section of the transceiver PIC, modulated light
received by the PIC, through an external coupler, is conveyed to a detector (either
monolithically integrated, heterogeneously assembled or external), which, through appropriate
circuitry (typically a trans-impedance amplifier and limiting amplifier), converts the output of
the detector into a corresponding electronic signal.
Figure 7 shows a schematic view of a four channel PIC transceiver, which operates as
described in 7.2 and 7.3.
7.2 Transmitter section
First, a laser diode is powered to provide a source of continuous wave light. In this example,
the laser is a separate device, which is attached to the PIC, though often the laser source is
located remotely and conveys continuous wave (CW) light to the PIC via a fibre.
The CW laser light is coupled into the PIC through a single polarization grating coupler
(SPGC) and the power is split equally across four waveguides. In each of the four waveguides,
the CW light is conveyed through a Mach-Zehnder interferometer (MZI) with high speed phase
modulators (HSPM) devices arranged in a "push-pull" configuration on each MZI waveguide
branch. The HSPM pair is driven by a differential electrical signalling voltage conveyed via the
small form factor pluggable (SFP) compliant high speed electrical interface. The application of
voltage difference on each HSPM gives rise to a corresponding change in refractive index

– 18 – IEC TR 63072-1:2017  IEC 2017
along the section of the MZI waveguide branch over which the HSPM operates. This in turn
causes opposite shifts in the phases of CW light passing in each waveguide branch. Upon
merging of the MZI waveguide branches, the two light signals recombine to either interfere
constructively, whereby the CW light leaves the MZI, or destructively whereby no light leaves
the MZI. This effectively gives rise to a modulated optical output driven by the differential
electrical signal.
The waveguide leaving the MZI leads to a single polarization grating coupler (SPGC), which
deflects the single polarization of light out of the waveguide and typically into an external
single-mode fibre.
A small fraction of the light leaving the MZI is coupled into a tap waveguide, which is then
conveyed to a monitor photodiode (PD). This is conveyed across an analogue-to-digital
converter circuit to a calibration circuit on the MZI. The calibration circuit controls the current
passing across two PIN junctions subtending a section of each MZI waveguide branch. Each
PIN junction can be used to change the refractive index of the waveguide section it subtends
by altering the charge density across it, thus it provides an additional means of tuning the
phase of light in each branch and is used to calibrate the MZI.
7.3 Receiver section
Modulated light is conveyed from an external conduit, typically a single-mode optical fibre,
into a polarization splitting grating coupler (PSGC), which decomposes the incident light into
two orthogonal polarizations and conveys each polarization component along a separate
waveguide. PIC waveguides are polarization sensitive, but the use of the PSGC means that
the incident fibre need not be arranged so that all light is conveyed in one polarization axis
and the incident fibre need not be adjusted so that said
...