photonics opinion
rhombus4
both electronic and photonic devices are Traditional definitions:
considered. In fact, over the last two Photonic Lightwave Circuits (PLC):
decades, the original term optoelectronic These are circuits based on passive waveguide components that are integrated on the
integrated circuit (OEIC) has been same substrate. PLCs do not include active devices. Most solutions to date use silica as
superseded by the term photonic integrated the platform material to maximize the benefit of the passive photonic function. It has been
circuit (PIC). PICs today do not incorporate difficult to utilize silica material for emitters and electronic functions, which has limited the
electronics; when they do, the term may architectures to passive solutions. Modulators (without lasers) in the traditional definition
evolve to a different acronym. are considered passive devices.
The traditional definitions for photonic Photonic Integrated Circuits (PIC):
integration are noted below, followed by PICs in the classic sense are passive and active waveguide optical components
newer definitions as the industry is integrated on the same substrate without electronics. Typical materials for PICs are InP,
beginning to adopt a more organized GaAs, and more recently silicon. Techniques such as wafer bonding of III-V materials that
approach with A-PICs, OE-PICs, etc. have emitting properties with silicon are allowing new vehicles for both photonic and
electronic functionality.
3.0: Drivers for photonic Optoelectronic Integrated Circuits (OEIC): OEICs are circuits that contain both passive
integration and active waveguide optical components integrated on the same substrate, but also with
Technology, whose development is to be electronic components such as field effect and bipolar transistors. Typical materials for
pursued for commercial rather than scientific OEICs have been III-V compounds such as InP and GaAs, but with the recent
reasons, should enable tangible economic developments of hybrid devices, silicon is beginning to find a home in this category.
and technological benefits. This is certainly
the case for PICs, which promise important
benefits across a wide range of attributes. New definitions:
At the simplest level, the case for PICs Active or Optoelectronic PICs
parallels that for silicon ICs: the ability to (A-PICs or OE-PICs):
monolithically integrate many distinct Such circuits enable the integration of optoelectronics functions and require an electrical
devices and functions onto a common chip contact (i.e., lasers, PIN detectors, modulators, switches, variable optical attenuators, and
vs. using many discrete components, amplifiers) in addition to supporting passive functions (i.e., waveguides, filters, and
thereby delivering important gains in multiplexers). The material of choice for these PICs is indium phosphide (InP) or gallium
packaging efficiency, smaller size and lower arsenide (GaAs) based materials owing to the ability of these materials to generate,
power use, increased reliability, and very amplify, or detect light in the 850 nm, 1310 nm, or
importantly, lower cost per device. It has 1500 nm fiber optic transmission windows, as well as to provide passive waveguides that
been continually argued, however, that the are transparent at these wavelengths.
benefits of PICs go beyond simple
densification and cost reduction; they All-Optical or Passive PICs (OO-PIC) –
enable increased functionality. This the OO refers to optical in; optical out: Such circuits are typically called planar lightwave
increased functionality drives end-user value circuits (PLC) that integrate purely passive functions such as waveguides, filters, and
by enabling the addition of cost-effective multiplexers. The material of choice for these types of PICs is silica on silicon, or, in the
functions that would otherwise not be case of modulators, lithium niobate. These PICs may be integrated using hybrid
economically viable, or technically possible, integration with active devices or PICs (for example, PIN photodiode arrays used in silica-
to incorporate. This superior value has been on-silicon PLC-based reconfigurable optical add/drop multiplexers, or ROADMs).
demonstrated many times in the
telecommunications fiber optic component Optoelectronic Integrated Circuit (OEIC) or Electronic-PIC (EPIC):
segment. It has also provided two Such circuits include electronic circuits which are different from A-PICs, OE-PICs, and
arguments for promoting the use of OO-PICs, which consider only the integration of optical component functions. OEICs
photonic integration: performance gains integrate both photonic components (either “active” or “passive” functions) with purely
(space, power reliability, and cost) as well electronic circuits—essentially the combination of photonic IC and silicon IC functions.
as increased functionality. Typical electrical-only functions that may be implemented on an OEIC include circuitry for
laser or modulator drivers, trans-impedance amplifiers (TIA), clock-data recovery (CDR),
While the benefits of larger-scale photonic or digital logic circuits similar to those implemented in silicon ICs.
integration have been conceptualized since
the invention of the IC, practical The traditional definitions are closely aligned to materials and substrate platforms, while
implementation and commercial deployment the newer definitions are aligned along functional solutions. The industry today uses a
have taken several decades due to combination of terms, although most practitioners still utilize the traditional definitions.
difficulties related to device design,
26
www.compoundsemiconductor.net October 2009
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44