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Amorphous Al2O3 is an attractive material for integrated photonics. Its low losses from the UV till the mid-IR together with the possibility of doping with different rare-earth ions permits the realization of active and passive functionalities in the same chip at the wafer level. In this work, the influence of reactive gas flow during deposition on the optical (i.e., refractive index and propagation losses) and material (i.e., structure of the layer) characteristics of the RF reactive sputtered Al2O3 layers is investigated and a method based on the oxidation state of the sputtering target is proposed to reproducibly achieve low loss optical guiding layers despite the continuous variation of the condition of the target along its lifetime.

Recently, quantum advantage over classical computation has been claimed using photons [1] . To control photonic quantum computations such as Boson sampling, a non-universal approach on quantum computation, large-scale quantum processors are needed [2] , [3] . To realize scalable and robust photonic quantum processors integrated photonics is a key technology. In our approach we use the integrated waveguide platform based on silicon nitride [4] , due to its low intrinsic losses and technological maturity. The low losses result in a high fidelity of the quantum photonics processor which is mandatory for reliable quantum computation while maturity of the platform allows for scaling up of the dimensions of the processor. Here, we present a universal 12-mode quantum photonics processor which is the largest of its kind to date.

Photonic processors are pivotal for both quantum and classical information processing tasks using light. In particular, linear optical quantum information processing requires both large-scale and low-loss programmable photonic processors. In this paper, we report the demonstration of the largest universal quantum photonic processor to date: a low-loss 12-mode fully tunable linear interferometer with all-to-all mode coupling based on stoichiometric silicon nitride waveguides.

Photonics integration is a key technology for realizing large-scale photonic quantum information processing. We demonstrate state-of-art reconfigurable photonic processors based on low-loss silicon nitride waveguide networks. We present the science behind such a processor, which consists of a large mesh of integrated reconfigurable Mach Zehnder interferometers. In this talk, we will present the newest results of the current generation of our programmable quantum photonic processors obtained by classical as well as quantum optical characterization. Furthermore, we show the challenges of scaling up quantum photonic processors and the range of potential applications of large-scale quantum information processing those will enable.

Aluminum oxide (Al2O3) is an emerging material in integrated photonics. It exhibits a very broad transparency window from the UV to the mid-IR, very low propagation losses and a high solubility for rare-earth ions leading to optical gain in different spectral ranges. Al2O3 can be deposited by different wafer-level deposition techniques, including atomic layer deposition and reactive magnetron sputtering, being compatible with the monolithic integration onto passive integrated photonics platforms, such as Si3N4, to which it provides optical amplification and lasing. When deposited at low temperatures, it is also compatible with integration onto CMOS chips. In this review, the state-of-the-art on the deposition, integration and device development in this photonic platform is described.

Whispering gallery mode resonator lasers hold the promise of an ultralow intrinsic limit of detection. However, the widespread use of these devices for biosensing applications has been hindered by the complexity and lack of robustness of the proposed configurations. In this work, we demonstrate biosensing with an integrated microdisk laser.

Three-dimensional (3D) characterization of nanomaterials is traditionally performed by either cross-sectional milling with a focused ion beam (FIB), or transmission electron microscope tomography. While these techniques can produce high quality reconstructions, they are destructive, or require thin samples, often suspended on support membranes. Here, we demonstrate a complementary technique allowing non-destructive investigation of the 3D structure of samples on bulk substrates. This is performed by imaging backscattered electron (BSE) emission at multiple primary beam energies - as the penetration depth of primary electrons is proportional to the beam energy, depth information can be obtained through variations in the beam acceleration. The detected signal however consists of a mixture of the penetrated layers, meaning the structure's three-dimensional geometry can only be retrieved after deconvolving the BSE emission profile from the observed BSE images. This work demonstrates this novel approach by applying a blind source separation deconvolution algorithm to multi-energy acquired BSE images. The deconvolution can thereby allow a 3D reconstruction to be produced from the acquired images of an arbitrary sample, showing qualitative agreement with the true depth structure, as verified through FIB cross-sectional imaging.

Reproducció del document publicat a: https://doi.org/10.1364/OL.44.005937, Whispering gallery mode resonator lasers hold the promise of an ultralow intrinsic limit of detection. However, the widespread use of these devices for biosensing applications has been hindered by the complexity and lack of robustness of the proposed configurations. In this work, we demonstrate biosensing with an integrated microdisk laser. Al2O3doped with Yb3+ was utilized because of its low optical losses as well as its emission in the range 1020–1050 nm, outside the absorption band of water. Single-mode laser emission was obtained at a wavelength of 1024 nm with a linewidth of 250 kHz while the microdisk cavity was submerged in water. A limit of detection of 300 pM (3.6 ng/ml) of the protein rhS100A4 in urine was experimentally demonstrated, showing the potential of the proposed devices for biosensing.

Low-cost, high-performance integration technologies are instrumental for active–passive integrated photonics devices. The monolithic integration of Al2O3 and Si3N4 is studied, enabling to combine the promising optical features of Si3N4 with the excellent optical gain characteristics of rare-earth-ion doped Al2O3. The Al2O3 and Si3N4 layers are separated by a thin SiO2 film and coupled by adiabatically width-tapered Al2O3 and thickness-tapered Si3N4 waveguides. In this paper, a detailed characterization of the couplers, as well as a study of the influence of the different design parameters and fabrication tolerances on the final device performance is presented. Test structures are characterized under transverse electric (TE) polarization. Measured loss per coupler is as low as 0.26 ± 0.03 dB at the wavelength of 1030 nm, and below 0.24 dB in the spectral window of 1460–1635 nm. Lateral misalignment of ±1 μ m results in less than 0.6 dB increase of the coupler loss at 1030 nm, and the tolerance of misalignment goes up to 1.7 μ m at the investigated longest wavelength of 1635 nm without introducing extra coupler losses. The reported integration technology paves the way toward a double-layer platform monolithically integrating Si3N4 and rare-earth-ion doped Al2O3 for active–passive photonic functionalities.

Nanophotonic waveguide enhanced Raman spectroscopy (NWERS) is a sensing technique that uses a highly confined waveguide mode to excite and collect the Raman scattered signal from molecules in close vicinity of the waveguide. The most important parameters defining the figure of merit of an NWERS sensor include its ability to collect the Raman signal from an analyte, i.e. ANDx201C;the Raman conversion efficiencyANDx201D; and the amount of ANDx201C;Raman backgroundANDx201D; generated from the guiding material. Here, we compare different photonic integrated circuit (PIC) platforms capable of on-chip Raman sensing in terms of the aforementioned parameters. Among the four photonic platforms under study, tantalum oxide and silicon nitride waveguides exhibit high signal collection efficiency and low Raman background. In contrast, the performance of titania and alumina waveguides suffers from a strong Raman background and a weak signal collection efficiency, respectively., info:eu-repo/semantics/published

Amorphous Al2O3 is an attractive material for integrated photonics, providing both active and passive functionalities. Al2O3 exhibits high solubility for rare-earth ions with moderate quenching of luminescence, a wide transparency window (150-7000 nm) and low propagation loss. It is therefore a very attractive material for visible, near- and mid-IR on-chip active devices. We have developed two different integration procedures to integrate Al2O3 onto passive photonic platforms. A double photonic layer integration scheme permits the low-loss integration of rare-earth ion doped Al2O3 onto the Si3N4 photonic platform. A single photonic layer integration scheme, based on the photonic damascene process, permits the creation of active and passive regions at the same level on a wafer, with the consequent reduction of the number of fabrication steps compared to the vertical integration of two materials. On-chip amplifiers on Si3N4 with more than 10 dB of net gain at 1550 nm as well as the realization of narrow linewidth lasers on active-passive Al2O3 for label-free sensing applications will be discussed.

We propose and experimentally demonstrate a modular microring laser (MML) cavity for sensing applications. The proposed MML permits much more design freedom compared with a traditional simple ring cavity by decoupling the performance parameters into several regions in the cavity. Thus, the different biosensor performance parameters can be optimized semi-independently limiting the need for trade-offs on the design of the biosensing device. The first generation MML has been fabricated and tested. A fiber-to-fiber slope efficiency of up to 1.2%, a temperature coefficient of 1.35 GHz/K and a 3σ limit of detection (LOD) of 3.1 × 10−7 RIU without averaging and 6.0 × 10−8 RIU with a 60 s averaging, has been measured for the MML sensor, which is a record-low LOD in on-chip ring cavity optical sensors. Further optimization is possible, capitalizing on the key advantage of the MML concept, namely the potential for designing the laser cavity to achieve the desired optimization goals.

Low-loss, broadband, and low phase deviation optical 90°hybrids based on 2 × 4 multimode interference couplers are firstly demonstrated using Si3N4 on SiO2 technology. Only a simple traditional design method of MMI based on self-imaging theory and a single-stripe Si3N4 waveguide geometry with only one step etching process are utilized. The characterization of the fabricated devices is carried out over a wide spectral window of 1520–1610 nm, showing that the measured phase error is less than 8°, and common-mode rejection ratios (CMRRs) are better than −20 dB. The measured total loss of the fabricated device including a 90°hybrid and a 3-dB coupler is

Al 2 O 3 microresonators were realized for sensing applications of both passive and active devices. Passive microring resonators exhibited quality factors up to 3.2×105 in air. A bulk refractive index sensitivity of ~100 nm/RIU was demonstrated together with a limit of detection of ~10−6 RIU. Functionalizing their surface allowed for the label-free detection of the biomarker rhS100A4 from urine with a limit of detection of 3 nM. Furthermore, single-mode Al 2 O 3 :Yb3+ microdisk lasers were realized that could operate in an aqueous environment. Upon varying the bulk refractive index their lasing wavelength could be tuned with a sensitivity of ~20 nm/RIU and a LOD of ~3×10−6 RIU.

Optical coupling for monolithic integration of Al2O3 and Si3N4 layers is presented using a vertical and lateral adiabatic taper. The measured loss of the fabricated couplers is 0.49±0.03 dB at the wavelength of 1030 nm.

The Al2O3 waveguide technology was explored for sensing applications. Passive microring resonators with a quality factor in air of 3.2×105 were developed with a bulk refractive index sensitivity of ~100 nm/RIU and limit of detection of ~10-6 RIU. These were functionalized to detect the biomarker rhS100A4 from urine down to concentrations of 3 nM. Furthermore, Al2O3:Yb3+ microdisk lasers were realized that exhibited single mode lasing operation in water. Their lasing wavelength was tuned by varying the bulk refractive index and a bulk refractive index sensitivity of ~20 nm/RIU with a LOD of ~3×10-6 was achieved.

Waveguide microring resonators sensors are numerously found in the Si-based technologies. Their operation, however, requires the operation of a tunable laser and the real-time monitoring of the location of their resonance peaks. An active material with gain could omit such operation through the detection of a laser-generated signal. Here, Al 2 O 3 is presented as an alternative technology that has the potential for such active sensing applications. Microring resonators of undoped and Er3+-doped Al 2 O 3 were fabricated and characterized. The undoped microring resonator was used for bulk refractive index sensing with a highest sensitivity of 95 nm/RIU and a limit of detection of 2.5e-6 RIU. After optical pumping the doped devices experienced the compensation of loss through internal gain, but the losses were too high to achieve lasing in the device. This work shows the feasibility of realizing passive sensors on the Al 2 O 3 platform and efforts are ongoing to transcend the platform from a passive to an active operation.

Si3N4 grown by low pressure chemical vapor deposition (LPCVD) on thermally oxidized silicon wafers is largely utilized for creating integrated photonic devices due to its ultra-low propagation loss and large transparency window (400 nm to 2350 nm). In this paper, an ultra-low-loss and broadband mode converter for monolithic integration of different materials onto the passive Si3N4 photonic technology platform is presented. The mode size converter is constructed with a vertically tapered Si3N4 waveguide that is then buried by a polymer or an Al2O3 waveguide. The influence of the various design parameters on the converter characteristics are investigated. Optimal designs are proposed, in which the thickness of the Si3N4 waveguide is tapered from 200 nm to ~40 nm. The calculated losses of the mode converters at 976 nm and 1550 nm wavelengths are well below 0.1 dB for the Si3N4-polymer coupler and below 0.3 dB for the Si3N4-Al2O3 coupler. The preliminary experimental results show good agreement with the design values, indicating that the mode converters can be utilized for the low-loss integration of different materials.

Al2O3 microresonators were realized for sensing applications of both passive and active devices. Passive microring resonators exhibited quality factors up to 3.2×105 in air. A bulk refractive index sensitivity of 100 nm/RIU was demonstrated together with a limit of detection of 10-6 RIU. Functionalizing their surface allowed for the label-free detection of the biomarker rhS100A4 from urine with a limit of detection of 3 nM. Furthermore, single-mode Al2O3:Yb3+ microdisk lasers were realized that could operate in an aqueous environment. Upon varying the bulk refractive index their lasing wavelength could be tuned with a sensitivity of 20 nm/RIU and a LOD of 3×10-6 RIU.

Amorphous Al2O3 is an attractive platform for integrated photonics, providing active and passive functionalities. We have developed an integration procedure to create active and passive regions at the same level on one wafer. This fabrication process reduces the number of fabrication steps compared to vertical integration of two materials. The main advantage is that all structures are defined within a single photolithography and etching step and are therefore automatically aligned. As a proof of principle, we demonstrated the luminescence of an active ring resonator with passive bus waveguide.