Emerging passive optical networks (PONs) standards target 25Gb/s and 50Gb/s systems, requiring high optical powers without amplification. Externally modulated lasers (EMLs) yield low chirp. However, achieving output modulated power exceeding 10 dBm is challenging due to modulator insertion losses and saturation.
In this invited presentation we will show our recent results in the development of EMLs based on semi-insulating buried heterostructure (SIBH) waveguide. We will present the main EML design rules and compromises, then apply them to different EMLs aiming at major telecom and datacom applications, with special focus on novel devices addressing the needs of emerging PON applications.
C. Koos, T. Kippenberg, L. Barry, A. Ramdane, F. Lelarge, W. Freude, P. Marin, J. Kemal, C. Weimann, S. Wolf, P. Trocha, J. Pfeifle, M. Karpov, A. Kordts, V. Brasch, R. Watts, V. Vujicic, A. Martinez, V. Panapakkam, N. Chimot
Chip-scale frequency comb sources are key elements for a variety of applications, comprising massively parallel optical communications and high-precision optical metrology. In this talk, we give an overview on our recent progress in the area of integrated optical comb generators and of the associated applications. Our experiments cover modulator-based comb sources, injection locking of gain-switched laser diodes, quantum-dash mode-locked lasers, as well as Kerr comb sources based on cavity solitons. We evaluate and compare the performance of these devices as optical sources for massively parallel wavelength division multiplexing at multi-terabit/s data rates, and we report on comb-based approaches for high-precision distance metrology.
We report on our recent advances on integrated hybrid InP/SOI transmitters using the Silicon Photonic fabrication technology. We demonstrate the direct modulation at 10 Gbits/s of different laser configurations such as wavelength tunable lasers, Distributed FeedBack (DFB) lasers and Chirp Managed Lasers (CMLs). We will also present the design, fabrication and characterization of various hybrid InP/SOI transmitters integrating lasers (tunable or DFB) and modulators (silicon or III-V) with modulation up to 32 Gbits/s.
This work presents an investigation of room temperature ultra-fast carrier dynamics in a p-doped dash-in-a-well structure emitting at 1.5 μm using single colour heterodyne pump-probe spectroscopy. This technique enabled simultaneous access to the gain and refractive index dynamics in various operational conditions including both the absorption and gain regime. Comprehensive analysis of the timescales related to carrier relaxation and escape processes in addition to the ’dynamical’ linewidth enhancement factor are presented and compared with results obtained from similar un-doped materials. The direct influence of the p-doping on the carrier dynamics is also discussed.
We demonstrate wavelength domain multiplexed (WDM) data transmission with a data rate of 14 Gbps based on optical
carrier generation with a single-section semiconductor mode-locked laser (SS-MLL) and modulation with a Silicon
Photonics (SiP) resonant ring modulator (RRM). 18 channels are sequentially measured, whereas the best recorded eye
diagrams feature signal quality factors (Q-factors) above 7. While optical re-amplification was necessary to maintain the
link budgets and therefore system measurements were performed with an erbium doped fiber amplifier (EDFA),
preliminary characterization done with a semiconductor optical amplifier (SOA) indicates compatibility with the latter
pending the integration of an additional optical filter to select a subset of carriers and prevent SOA saturation. A
systematic analysis of the relative intensity noise (RIN) of isolated comb lines and of signal Q-factors indicates that the
link is primarily limited by amplified spontaneous emission (ASE) from the EDFA rather than laser RIN. Measured RIN
for single comb components is below -120 dBc/Hz in the range from 7 MHz to 4 GHz and drops to the shot noise level at
higher frequencies.
The combination of low chirp Quantum dash directly modulated lasers with an optical filter have shown promising data transmission performances with 10Gb/s transmission distances in the range of 0-100 km, in full compliance with the current standardization for NGPON2. This paper describes in details the operation of such transmitters, including the enhancement in modulation bandwidth of laser induced by the passive filter.
Optical frequency combs have great potential for ultra-high bit rate telecommunications e.g. optical orthogonal
frequency-division multiplexing superchannels. For frequency comb generation, monolithic Quantum Dash
semiconductor mode-locked lasers are very attractive candidates owing to their broadband optical spectrum, inherent
intrinsic low noise and compactness. The active region is based on InAs nanostructures grown on InP for operation in
the 1.55 μm window. Owing to enhanced nonlinear effects, a single gain section generates short pulses in the modelocking
regime without resorting to an absorber section. An optical bandwidth over 1.3 THz yielding over 100 channels,
10 GHz spaced, is reported. Mode-locking properties are analyzed in the frequency domain using the concept of supermodes.
An Allan deviation down to ~ 10-9 is reported for these passively mode-locked lasers. The low timing jitter, longterm
stability and high channel count of these QD based combs are of great potential for Tb/s data transmission with
only one single FP type laser source.
Silicon photonics has reached a considerable level of maturity, and the complexity of photonic integrated circuits (PIC) is steadily increasing. As the number of components in a PIC grows, loss management becomes more and more important. Integrated semiconductor optical amplifiers (SOA) will be crucial components in future photonic systems for loss compensation. In addition, there are specific applications, where SOAs can play a key role beyond mere loss compensation, such as modulated reflective SOAs in carrier distributed passive optical networks or optical gates in packet switching. It is, therefore, highly desirable to find a generic integration platform that includes the possibility of integrating SOAs on silicon. Various methods are currently being developed to integrate light emitters on silicon-on-insulator (SOI) waveguide circuits. Many of them use III-V materials for the hybrid integration on SOI. Various types of lasers have been demonstrated by several groups around the globe. In some of the integration approaches, SOAs can be implemented using essentially the same technology as for lasers. In this paper we will focus on SOA devices based on a hybrid integration approach where III-V material is bonded on SOI and a vertical optical mode transfer is used to couple light between SOI waveguides and guides formed in bonded III-V semiconductor layers. In contrast to evanescent coupling schemes, this mode transfer allows for a higher confinement factor in the gain material and thus for efficient light amplification over short propagation distances. We will outline the fabrication process of our hybrid components and present some of the most interesting results from a fabricated and packaged hybrid SOA.
P. Kaspar, C. Jany, A. Le Liepvre, A. Accard, M. Lamponi, D. Make, G. Levaufre, N. Girard, F. Lelarge, A. Shen, P. Charbonnier, F. Mallecot, G.-H. Duan, J. Gentner, J.-M. Fedeli, S. Olivier, A. Descos, B. Ben Bakir, S. Messaoudene, D. Bordel, S. Malhouitre, C. Kopp, S. Menezo
The lack of potent integrated light emitters is one of the bottlenecks that have so far hindered the silicon photonics platform from revolutionizing the communication market. Photonic circuits with integrated light sources have the potential to address a wide range of applications from short-distance data communication to long-haul optical transmission. Notably, the integration of lasers would allow saving large assembly costs and reduce the footprint of optoelectronic products by combining photonic and microelectronic functionalities on a single chip. Since silicon and germanium-based sources are still in their infancy, hybrid approaches using III-V semiconductor materials are currently pursued by several research laboratories in academia as well as in industry. In this paper we review recent developments of hybrid III-V/silicon lasers and discuss the advantages and drawbacks of several integration schemes. The integration approach followed in our laboratory makes use of wafer-bonded III-V material on structured silicon-on-insulator substrates and is based on adiabatic mode transfers between silicon and III-V waveguides. We will highlight some of the most interesting results from devices such as wavelength-tunable lasers and AWG lasers. The good performance demonstrates that an efficient mode transfer can be achieved between III-V and silicon waveguides and encourages further research efforts in this direction.
Indium phosphide and associated epitaxially grown alloys is a material system of choice to make photonic integrated circuits for microwave to terahertz signal generation, processing and detection. Fabrication of laser emitters, high speed electro-optical modulators, passive waveguides and couplers, optical filters and high speed photodetectors is well mastered for discrete devices. But monolithic integration of them while maintaining good performances is a big challenge. We have demonstrated a fully integrated tunable heterodyne source designed for the generation and modulation of sub-Terahertz signals. This device is to be used for high data-rate wireless transmissions. DFB lasers, SOA amplifiers, passive waveguides, beam combiners, electro-optic modulators and high speed photodetectors have been integrated on the same InP-based platform. Millimeter wave generation at up to 120 GHz based on heterodyning the optical tones from two integrated lasers in an also integrated high bandwidth photodetector has been obtained.
Silicon photonics is attracting large attention due to the promise of fabricating low-cost, compact circuits that integrate photonic and microelectronic elements. It can address a wide range of applications from short distance data communication to long haul optical transmission. Today, practical Si-based light sources are still missing, despite the recent demonstration of an optically pumped germanium laser. This situation has driven research to the heterogeneous integration of III-V semiconductors on silicon through wafer bonding techniques. This paper reports on recent advances on integrated hybrid InP/SOI lasers and transmitters using a wafer bonding technique made in particular at III-V Lab, France.
We present the first demonstration of InAs/InP Quantum Dash based single-section frequency comb generator designed for use in photonic integrated circuits. The laser cavity is closed using a specific Bragg reflector without compromising the mode-locking performance of the laser. This enables the integration of single-section mode- locked laser on photonic integrated circuits as on-chip frequency comb source. As a demonstration, we integrate the Fabry Perot laser with a semiconductor optical amplifier. Such a device could be used for amplification or modulation of the frequency generated comb. We thus investigate the device operation to obtain a NRZ modulated comb.
Monolithic semiconductor passively mode locked lasers (MLL) are very attractive components for many applications
including high bit rate telecommunications, microwave photonics and instrumentation. Owing to the three dimensional
confinement of the charge carriers, quantum dot based mode-locked lasers have been the subject of intense investigations
because of their improved performance compared to conventional material systems. Indeed, the inhomogeneous gain
broadening and the ultrafast absorption recovery dynamics are an asset for short pulse generation. Moreover, the weak
coupling of amplified spontaneous emission with the guided modes plus low loss waveguide leads to low timing jitter.
Our work concentrates on InAs quantum dash nanostructures grown on InP substrate, intended for applications in the
1.55 μm telecom window. InAs/InP quantum dash based lasers, in particular, have demonstrated efficient mode locking
in single section Fabry-Perot configurations. The flat optical spectrum of about 12 nm, combined with the narrow RF
beat note linewidth of about 10 kHz make them a promising technology for optical frequency comb generation.
Coherence between spectral modes was assessed by means of spectral phase measurements. The parabolic spectral phase
profile indicates that short pulses can be obtained provided the intracavity dispersion can be compensated by inserting a
single mode fiber.
In this paper we show that using a DVS-BCB adhesive bonding process compact heterogeneously integrated III-V/silicon single mode lasers can be realized. Two new designs were implemented: in a first design a multimode interferometer coupler (MMI) – ring resonator combination is used to provide a comb-like reflection spectrum, while in a second design a triplet-ring reflector design is used to obtain the same. A broadband silicon Bragg grating reflector is implemented on the other side of the cavity. The III-V optical amplifier is heterogeneously integrated on the 400nm thick silicon waveguide layer, which is compatible with high-performance modulator designs and allows for efficient coupling to a standard 220nm high index contrast silicon waveguide layer. In order to make the optical coupling efficient, both the III-V waveguide and the silicon waveguide are tapered, with a tip width of the III-V waveguide of around 500nm. The III-V thin film optical amplifier is implemented as a 3μm wide mesa etched through to the n-type InP contact layer. In this particular device implementation the amplifier section was 500μm long. mW-level waveguide coupled output power at 20°C and a side mode suppression ratio of more than 40dB is obtained.
In this work we present results from high performance silicon optical modulators produced within the two largest silicon
photonics projects in Europe; UK Silicon Photonics (UKSP) and HELIOS. Two conventional MZI based optical
modulators featuring novel self-aligned fabrication processes are presented. The first is based in 400nm overlayer SOI
and demonstrates 40Gbit/s modulation with the same extinction ratio for both TE and TM polarisations, which relaxes
coupling requirements to the device. The second design is based in 220nm SOI and demonstrates 40Gbits/s modulation
with a 10dB extinction ratio as well modulation at 50Gbit/s for the first time. A ring resonator based optical modulator,
featuring FIB error correction is presented. 40Gbit/s, 32fJ/bit operation is also shown from this device which has a 6um
radius. Further to this slow light enhancement of the modulation effect is demonstrated through the use of both
convention photonic crystal structures and corrugated waveguides. Fabricated conventional photonic crystal modulators
have shown an enhancement factor of 8 over the fast light case. The corrugated waveguide device shows modulation
efficiency down to 0.45V.cm compared to 2.2V.cm in the fast light case. 40Gbit/s modulation is demonstrated with a
3dB modulation depth from this device. Novel photonic crystal based cavity modulators are also demonstrated which
offer the potential for low fibre to fibre loss. In this case preliminary modulation results at 1Gbit/s are demonstrated.
Ge/SiGe Stark effect devices operating at 1300nm are presented. Finally an integrated transmitter featuring a III-V
source and MZI modulator operating at 10Gbit/s is presented.
The effect of controlled optical feedback has been investigated for InAs/InP laser structures operating in the 1.55
μm fiber window. Mode locked lasers in particular show extremely small phase noise when subjected to optical
feedback, implying a very low timing jitter which is of interest for many applications.
The comparison of relative intensity noise (Rin) shows improved performances, for quantum dash laser (QD)
compared to the ones of bulk medium structures. We introduced a statistical measurement through a coupling
parameter that reveals the impact of strong damping on the competition between modes or the so-called partition
noise. The existence of a strong damping in QD laser prevents the relaxation frequency from being observed
in the coupling parameter, which makes the noise to appear as if the laser lines were inhomogeneous. However
the method also enables the characterization of the coupling strength between modes, showing again differences
between QD and bulk structures.
F. Lelarge, R. Brenot, B. Rousseau, F. Martin, G. Patriarche, F. Poingt, L. LeGouezigou, O. Le Gouezigou, C. Dernazaretian, E. Derouin, O. Drisse, F. Pommereau, A. Accard, M. Caligaro, D. Make, J.-G. Provost, P. Resneau, B. Dagens, F. van-Dijk, M. Krakowski, G. H. Duan
We report on the recent advances in InP-based Quantum Dashes (Qdashes) material for 1.55μm optoelectronic devices.
We achieve highly uniform, reproducible and wavelength-controlled Qdashes, with a length ranging from 50nm to
500nm depending on the growth conditions. These Qdashes lead either to high modal gain distributed feedback (DFB)
lasers or low chirp semiconductor optical amplifier (SOA). Moreover, we demonstrate that Qdashes are compatible with
buried ridge stripe and shallow ridge technology and lead to very reliable lasers. Directly modulated lasers with 10GHz
bandwidth are demonstrated in continuous wave mode operation. 10Gb/s transmission over 25km in semi-cooled
operation is achieved using DFB buried lasers. Qdashes optimization leads to SOA with internal gain of 10 dB and a -3dB optical bandwidth of 120 nm at 50°C, paving the way for semi-cooled CWDM optical sources. Furthermore, low
chirp Qdashes SOA are evaluated as optical boosters after a modulated source. Although we still observe overshoots on
the amplified signal, the chirp, even in their saturation regime, is low enough to allow for 50 km of transmission at
10Gb/s.
A. Ramdane, A. Martinez, S. Azouigui, D.-Y. Cong, K. Merghem, A. Akrout, C. Gosset, G. Moreau, F. Lelarge, B. Dagens, J.-G. Provost, A. Accard, O. Le Gouezigou, I. Krestnikov, A. Kovsh, M. Fischer
This paper presents recent progress in the field of semiconductor lasers based on self-assembled quantum dots grown
either on GaAs or InP substrates.
Quantum dot (QD) based lasers are attracting a lot of interest owing to their remarkable optoelectronic properties that
result from the three dimensional carrier confinement. They are indeed expected to exhibit much improved performance
than that of quantum well devices. Extremely low threshold currents as well as high temperature stability have readily
been demonstrated in the InAs/GaAs material system.
The unique properties of quantum dot based active layers such as broad optical gain spectrum, high saturation output
power, ultrafast gain dynamics and low loss are also very attractive for the realization of mode-locked lasers.
Recent results in the field of directly modulated InAs/GaAs lasers emitting in the 1.3 μm window are discussed. We
report in particular on temperature independent linewidth enhancement factor (or Henry factor αH) up to 85°C. This is a
key parameter which determines many laser dynamic properties. Optical feedback insensitive operation of specifically
band-gap engineered devices, compatible with high bit rate isolator-less transmission is also reported at 1.55 μm.
Monolithic mode locked lasers based on InAs/InP quantum dashes have been investigated for 1.55 μm applications. Subpicosecond
pulse generation at very high repetition rates (> 100 GHz) is reported for self-pulsating one-section Fabry
Perot devices. Specific applications based on these compact pulse generators including high bit rate clock recovery are
discussed.
Guang-Hua Duan, F. Lelarge, B. Dagens, R. Brenot, A. Accard, A. Shen, F. van Dijk, D. Make, O. Le Gouezigou, L. Le Gouezigou, J.-G. Provost, F. Poingt, J. Landreau, O. Drisse, E. Derouin, B. Rousseau, F. Pommereau
This paper summarizes recent advances on InAs/InP mode-locked quantum dashes (QD) lasers, and their applications for
all-optical clock recovery, short pulse generation and millimeter wave generation. We demonstrate that QD FP lasers,
owing to the small confinement factor and the 3D quantification of electronic energy levels, exhibit a beating linewidth
as narrow as 15 kHz. Such an extremely narrow linewidth, compared to their QW or bulk counterparts, leads to the
excellent phase noise and time jitter characteristics when QD lasers are actively mode-locked. We report also on an
actively mode-locking tunnel injection quantum dash Fabry-Perot laser diode at 42.7GHz, generating nearly Fourier
transform limited pulses with a pulse width of 2ps over 16nm.
We report on the modulation spectroscopy investigation (in a form of photoreflectance (PR)) of self-assembled InAs/GaInAsP quantum dash structures grown by gas source molecular beam epitaxy on InP (100) substrates and designed for laser applications at 1.55 μm wavelength range in two different architectures: dash-in-a-barrier and dash-in-a-well. The dashes parameters have been determined by cross-sectional and plane-view transmission electron microscopy to be of typical height and width of about 2 per 20 nm and length from 50 to more than 200 nm, depending on the growth conditions. The part of the PR spectra related to the quantum dash layer has revealed several well distinguished transitions with the energy separation between the ground state and first excited state ones of about 150 meV independently of the length of the dashes for the dash-in-a-barrier and twice less for dash-in-a-well-designs, respectively. Our theoretical analysis based on effective mass approximation calculations has shown that all the higher order state transitions are related to the InAs wetting layer quantum well, where its parameters, as WL thickness and conduction band offset ratio, have been estimated on the base of agreement with the experimental data. The PR-based optical properties have found confirmation in the PL thermal quenching and device characteristics.
Quantum dot (QD) materials offer attractive performances for the development of lasers and amplifiers at 1.55μm. The
3-D quantification of the energy levels in QD leads to several advantages, such as high optical gain and efficiency, low
sensitivity to temperature variations, low noise and low linewidth enhancement factor. We shall present in this paper the
growth and basic properties of QD materials for lasers and amplifiers, and device performances with particular interest
for optical communications and microwave transmission.
Practical realizations of 2D (planar) photonics crystal (PhC) are either on a membrane or etched through a conventional heterostructure. While fascinating objects can emerge from the first approach, only the latter approach lends itself to a progressive integration of more compact PhC's towards monolithic PICs based on InP. We describe in this talk the various aspects from technology to functions and devices, as emerged from the European collaboration "PCIC." The main technology tour de force is deep-etching with aspect ratio of about 10 and vertical sidewall, achieved by three techniques (CAIBE, ICP-RIE, ECR-RIE). The basic functions explored are bends, splitters/combiners, mirrors, tapers, and the devices are filters and lasers. At the end of the talk, I will emphasize some positive aspects of "broad" multimode PhC waveguides, in view of compact add-drop filtering action, notably.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.