Chilas develops off-the-shelf laser sources based on hybrid integration of Photonic Integrated Chips (PICs). Combining the high optical powers of semiconducting optical amplifiers (SOAs) with low-loss wavelength tunable mirror structures on Si3N4 PICs results in compact and robust tunable laser sources. These extended cavity diode lasers (ECDLs) exhibit unique characteristics like wide tuning ranges (>100 nm), ultra-narrow linewidths (<1 kHz) and high output powers. Here we present up to 162.5 mW of optical output power by combining two SOAs inside a single cavity, thereby scaling the output power without the need of additional optical amplification on the output port. The presented laser operates inside the telecom C-band, but the strategy can be tailored to other wavelengths like 850 nm, 780 nm and 690 nm, where Si3N4 plays a key role. This new generation of hybrid integrated ECDLs, exhibiting high optical output powers, wide wavelength tuning ranges and ultra narrow linewidths, opens up a wide range of applications.
We propose optical injection locking (OIL) injecting for the first-time a hybrid InP-Si3N4 laser source using another laser integrated on the same chip for microwave generation through optical heterodyning in Ka-, Q- and V-bands. A study of the drift exhibited by the devices will be performed as key parameter of lasers. The amount of free-running drift exhibited by the lasers and a way to minimize as much as possible. According to the measured drift that goes in the worst case up to 520 MHz. However, the electric drift of the beat-note RF signal keeps below 50 MHz thanks of being thermally stabilize over the same conditions. To eliminated the drift, an optical injection locking of one InP/Si3N4 hybrid integrated laser have been done by injecting another hybrid laser integrated on the same chip for the first time. We have demonstrated a locking range demonstrated a locking range of 1.86 GHz.
We propose a microwave photonic band-pass filter in the TriPleX® waveguide technology, capable of performing channel selection in flexible DEMUX satellite systems. The proposed channel selector consists of 2 stages of filtering, that enable fully reconfigurable central frequency and channel bandwidth tuning in the Ka-, Q- and V-band. The first stage of filtering is based on a Coupled Ring Optical Waveguide (CROW) filter and serves as channel bandwidth regulator. The CROW filter includes 8 ring resonators, each with a length of 7.38 cm, corresponding to a Free Spectral Range (FSR) of 2.6667 GHz. Bandwidth reconfigurability is achieved by using ultra low-loss, stress-optic lead zirconate titanate (PZT)-based tunable couplers between the ring resonators, while central frequency tunability is enabled for the whole Ka-band by incorporating a tunable PZT-based phase shift on each ring resonator. The second stage of filtering consists of Asymmetric Mach-Zehnder Interferometer (AMZI) - lattice filters and serves as FSR extender. AMZI lattice filters with FSR of 5.3334 GHz and 10.6668 GHz, respectively, are used to expand the central frequency tunability of the channel selector in the Q- and V-band. The lattice filters are also equipped with tunable phase shifters to allow for tunability in the central frequency. The proposed 2-stage channel selector filter has a fFSR=10.6668 GHz and exhibits a tunable passband bandwidth from 125 MHz to 1000 MHz. The passband insertion loss and group delay variation are < 0.9 dB and 2.8 ns, while channel isolation is higher than 50 dB. Additional presentation content can be accessed on the supplemental content page.
We present ultra-low power stress optic actuators for high-speed switching in photonic integrated circuits using the standard silicon nitride TriPleX™ platform. The stress-optic actuator is created by a piezoelectric layer (lead zirconate titanate, PZT) on top of a Si3N4-based TriPleX™ waveguide in our standard Asymmetric Double Stripe (ADS) cross section. The top cladding thickness in between the actuator and the waveguide is chosen to achieve minimal optical loss (≤0.01dB/cm). The electrodes are placed on the top of- and directly below the PZT layer allowing the generation of a vertical electric field across the layer. This electrical field deforms the PZT layer by means of the piezoelectric effect. As a consequence of the PZT deformation stress is induced in the underlying waveguide. In this way, the refractive index of the waveguide is controlled by the stress-optic effect brought about by actuating the PZT layer. To demonstrate the stress-optic based phase actuation experimentally, a Mach-Zehnder Interferometer (MZI) is employed. The MZI is designed for operation at a wavelength of 1550 nm. We measure a half-wave voltage-length product (Vπ·cm) of 16 V·cm, while the half-wave-voltage length loss product (Vπ ·L·α) is 1.6 V·dB only. The 2π phase shift would be at 42 V. The measured response time is 4.25 μs. The quasi-DC power dissipation is able to go down to 1 μW. Compared with conventional thermo-optic actuators these characteristics show a dramatic improvement, being a factor of 50 faster in terms of switching speed and a factor of 100 000 lower in terms of quasi-DC power dissipation. This makes stress-optic actuators an attractive choice for the next generation integrated photonic circuits where ultra-low quasi-DC power dissipation and/or fast switching time and operation in the MHz range are required.
Synthetic Aperture Radar (SAR) is a well-known technique for remote sensing applications with great advantages like uninterrupted imaging capabilities even at night or in presence of cloud cover. However, spaceborne SAR sensors face major challenges like cost and size, which are among the great barriers against their applicability for future constellations of low-Earth observation applications. SAR sensors are not compact and require large or medium-sized satellites weighting hundred kilograms or more, which cost hundreds million dollars. To solve these challenges, the recently started SPACEBEAM project, funded by the European Commission, aims at developing a novel SAR receiver approach, i.e., the Scan-on-Receive (SCORE), exploiting a hybrid integrated optical beamforming network (iOBFN) that also realizes the electro-photonic down-conversion of RF signals. The compactness and frequency flexibility of the proposed photonic solution complies with the requirements of future constellations of low-Earth orbit satellites in terms of size, weight, power consumption, and cost. A high-level representation of the SCORE SAR receiver module based on the multi-functional hybrid photonic integrated circuit (PIC), with 12 input RF channels and 3 output beam-formed IF channels, is shown in the submitted PDF document. For this design, we target the development of an X-band SCORE-SAR receiver having a swath width of 50 km (5 times wider than state-of-art spaceborne SAR systems), and enabling 1.5 m spatial resolution in both along-track and across-track directions. During the conference, we will present the design and specifications of the SCORE-SAR receiver at equipment level, where we aim at a hermetically packaged PIC that is also designed for space compliance. We target a flight-design for the RF front-end and control electronics, enabling the electro-photonic frequency down-conversion of the RF signals and the fast control of the PZT-driven iOBFN with <300 ns switching time.
Hybrid integration of semiconductor optical amplifiers with frequency-selective feedback circuits, implemented using low-loss Si3N4 waveguides, enables robust chip-sized lasers with outstanding properties. Deploying ring resonators as a tunable feedback filter provides single-mode operation over a wide wavelength range. Moreover, these rings resonantly enhance the cavity length, which results in ultra-narrow intrinsic linewidth, as low as 40 Hz.
Here, we present an overview on state-of-the-art developments regarding these lasers. We compare linewidth and tuning results for different feedback circuit configurations. Finally, we report on the first demonstration of a hybrid-integrated semiconductor laser that operates in the visible wavelength range.
Ultra-narrow linewidth tunable hybrid integrated lasers are built from a combination of indium phosphide (InP) and silicon nitride-based TriPleX™. By combining the active functionality of InP with the ultra-low loss properties of the TriPleX™ platform narrow linewidth lasers in the C-band are realized. The InP platform is used for light generation and the TriPleX™ platform is used to define a long cavity with a wavelength-selective tunable filter. The TriPleX™ platform has the ability to adapt mode profiles over the chip and is extremely suitable for mode matching to the other platforms for hybrid integration. The tunable filter is based on a Vernier of micro-ring resonators to allow for single-mode operation, tunable by thermo-optic or stress-induced tuning. This work will show the operational principle and benefits of the hybrid lasers and the state of the art developments in the realization of these lasers. High optical powers ( <100 mW) are combined with narrow linewidth (< 1 kHz) spectral responses with tunability over a large (>100 nm) wavelength range and a low relative intensity (< -160 dB/Hz).
The presentation slides for “European Network for High Performance Integrated Microwave Photonics” are available at http://doi.org/10.1117/12.2536107, under the Supplemental Content tab.
Photonic Integrated Circuit (PIC) technology is becoming more and more mature and the three main platforms that offer Multi Project Wafer runs (Indium Phosphide (InP), Silicon on Insulator (SOI) and the silicon nitride based TriPleX platform) each have their own unique selling points. New disruptive PIC based modules are enabled by combinations of the different platforms complementing each other in performance. In particular the InP-TriPleX combination are two very complementary technologies. Combining them together yields for instance tunable ultra-narrow linewidth lasers extremely suitable for telecom and sensing applications. Also microwave photonics modules for Optical Beam Forming Networks and 5G communication can, and have been realized with this combination. Important part of this combination is the integration of the different platforms in modules via cost effective assembly techniques. This talk will present the combination of both technologies, the interconnection issues faced in the assembly process and latest measurement results on these hybrid integrated devices.
Over the past few years considerable attention has been focussed on the inclusion of flexibility in communication satellite payloads. The purpose of this flexibility is to enable a given satellite on command to support different frequency plans, re-configure coverage in response to changing traffic demands and re-configure interconnectivity between coverages.
In this work, we demonstrate the first stress-optic modulator in a silicon nitride-based waveguide platform (TriPleX) in the telecommunication C-band. In our stress-optic phase modulator the refractive index of the waveguiding materials is controlled by the stress-optic effect induced by actuating a 2 μm thick PZT layer on top of the TriPleX waveguide geometry. The efficiency of the modulator is optimized by, amongst others, focusing the applied stress in the waveguide core region through a local increase of the top cladding. Using a Mach-Zehnder interferometer, we measured a half-wave voltage, Vπ, at 34 V at a wavelength of 1550 nm using a modulator with a total length of 14.8 mm. The measured static power consumption of our stress-optic modulator is in the μW-region as it is only determined by small leakage currents (< 0.1 μA), while the dynamic power consumption at a rise time of 1 ms (1 kHz excitation) is less than 4 mW per modulator. The stress optical modulator goes with an excess loss of 0.01 dB per modulator only. This is in line with the typical low loss characteristics of TriPleX waveguides, being < 0.1 dB/cm at a wavelength of 1550 nm. These specifications make stress-optic modulators an excellent choice for next generation optical beam forming networks with a large number of actuators in silicon photonics in general and in the TriPleX platform in particular.
In this article a selection of highlights of the TriPleX™ technology of LioniX is given. The basic waveguide technology is explained with recent benchmark measurements done by University California Santa Barbara (UCSB) and University Twente (UT-TE). In order to show the low loss transparency over a wide wavelength range three examples of applications in different wavelength regimes are described in more detail. These are the Integrated Laser Beam Combiner (ILBC) of XiO Photonics in the visible light, a ringresonator sensing platform of LioniX around 850 nm and a phased array antenna with an Optical Beam Forming Network in the 1550 nm band. Furthermore it is shown that the technology is easily accessible via Multi Project Wafer Runs for which the infrastructure and design libraries are also set up.
We present a new class of low-loss integrated optical waveguide structures as CMOS-compatible industrial standard for photonic integration on silicon or glass. A TriPleXTM waveguide is basically formed by a -preferably rectangular- silicon nitride (Si3N4) shell filled with and encapsulated by silicon dioxide (SiO2). The constituent materials are low-cost stoichiometric LPVCD end products which are very stable in time. Modal characteristics, birefringence, footprint size and insertion loss are controlled by design of the geometry. Several examples of new applications will be presented to demonstrate its high potential for large-scale integrated optical circuits for telecommunications, sensing and visible light applications.
In this paper a novel CW laser-compatible, squint-free, continuously tunable ring resonator-based optical beamformer
mechanism for a phased array receiver system is proposed and partly demonstrated. When the optical delay elements and
optical signal processing circuitry are integrated on a chip, a single-chip optical beam forming network (OBFN) is
obtained. The optical delay elements are ideally continuously tunable to achieve continuous control of the beam
direction, and should have a flat delay and magnitude response over the signal band, to avoid distortion. In the proposed
system architecture, filter-based optical single-sideband suppressed-carrier modulation and balanced coherent optical
detection are used. Such architecture has significant advantages over a straightforward architecture using optical
intensity modulation and direct optical detection, namely reduced complexity of the OBFN chip, and enhanced dynamic
range. Measurements on an actual 1×8 OBFN chip and an optical sideband filter chip are presented. Both are realized in
CMOS-compatible planar optical waveguide technology (TriPleX).
A polarization independent optical waveguide structure suited for operation in the third communication window has been developed and optimized towards minimized dependence on deviations in the processing parameters and very low processing complexity. The tolerance analysis and optimization have been based on the thin film parameters of the widely applied silicon oxynitride technology. The silicon oxynitride layers have typically a material birefringence (nTMnTE) between 1-2 x 10-3 and can be deposited within a uniformity and reproducibility of 1% in thickness (d), 5x10-4 in refractive index (n) and 100 nm in channel width (w). The optimized waveguide structure meets the criterion of a channel birefringence (Δneff,TM-TE) within 5x10-5 taking the processing tolerance into account. Moreover, it was found
that the channel birefringence is thickness independent (within the 10-5 criterion) over a range of up to 200 nm
(δΔneff,TM-TE ,/ δd = 0). Furthermore, the optimized waveguide is fulfilling the remaining demands of the application
aimed at, such as monomodality, low fiber to chip coupling loss (< 0.5 dB/facet) and low loss bends with a radius down to 600 nm. This waveguiding structure has been applied for the realization of a passband flattened add-drop multiplexing device (or interleaver) with 0.4 nm free spectral range and 0.03 nm TE-TM shift. Based on this shift, a polarization dependence of 3 x 10-5 was calculated for the optical waveguides.
In this paper, we demonstrate a thermo-optically tunable periodic wavelength filter (interleaver) with a 50 GHz free spectral range (FSR). It has an almost rectangular wavelength response and consists of an asymmetric Mach-Zehnder Interferometer (MZI) consisting of two tunable 3dB couplers interconnected by two waveguide channels of unequal length, with a ring resonator coupled to one of the branches of the MZI. The filter is fabricated in silicon oxynitride (SiON) waveguide technology. The bar and cross transmission spectra and chromatic dispersion of the filter have been measured and passband flattening and stopband broadening was observed in good agreement with the simulation. The isolation was 15 dB and 12 dB for TM and TE polarized light respectively, which was lower than the designed 29 dB. The main cause of lower isolation is an inaccuracy of the realization of the power coupling coefficient to the ring (59% instead of the designed 82%). The measured dispersion of the filter varies from 0 ps/nm at the center to 1660 ps/nm at the edge of the passband.
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