| 1. |
- Buffolo, M., et al.
(författare)
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Modeling of the Optical and Electrical Degradation of 845 nm VCSILs
- 2023
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Ingår i: 2023 Conference on Lasers and Electro-Optics, CLEO 2023.
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Konferensbidrag (refereegranskat)abstract
- Optical and electrical degradation of novel micro-transfer-printed VCSILs is investigated. Modeling of experimental data suggests that the main degradation mechanism is represented by the relocation of impurities, originating from the p-side, toward the active region.
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| 2. |
- Zenari, M., et al.
(författare)
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Addressing the electrical degradation of 845 nm micro-transfer printed VCSILs through TCAD simulations
- 2023
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Ingår i: Proceedings of the International Conference on Numerical Simulation of Optoelectronic Devices, NUSOD. - 2158-3234. ; 2023-September, s. 91-92
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Konferensbidrag (refereegranskat)abstract
- In this work we present the electrical modeling of novel 845 nm vertical-cavity silicon-integrated lasers (VCSILs) for silicon photonics (SiPh). We tested the reliability of the devices by submitting them to high current stress, corresponding to ≈ 20xIth, to observe the degradation as a function of time. During the stress experiment, we monitored the electrical characteristics at regular intervals and we observed two separate degradation phenomena: the series resistance increment and the lowering of the turn-on voltage. Thanks to a Poisson-drift diffusion simulator we simulated the I-V characteristics and the band diagrams to interpret the degradation phenomena. The results of the simulations confirmed that the electrical degradation can be caused by the diffusion of compensation impurities originating from the p-contact layers. The same mechanism was also responsible of the optical degradation of the devices.
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| 3. |
- Zenari, M., et al.
(författare)
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Analysis of defect-related optical degradation of VCSILs for photonic integrated circuits
- 2023
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 12439
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Konferensbidrag (refereegranskat)abstract
- Laser diodes are of paramount importance for on-chip telecommunications applications, and a wide range of sensing devices that require near-infrared sources. In this work, the devices under test are vertical-cavity silicon-integrated lasers (VCSILs) designed for operation at 845 nm in photonic integrated circuits (PICs). We focus on the analysis of the degradation of the optical performance during aging. To investigate the reliability of the devices, we carried out several stress tests at constant current, ranging from 3.5 mA to 4.5 mA representing a highly accelerated stress condition. We observed two different degradation modes. In the first part of the experiments, the samples exhibited a worsening of the threshold current, but the sub-threshold emission was unaffected by degradation. We associated this behavior to the diffusion of impurities that, from the p-contact, were crossing the upper mirror implying a worsening of the DBR optical absorption. In the second stage of the stress test, the devices showed a higher degradation rate of the threshold current, whose variation was found to be linearly correlated to the worsening of the sub-threshold emission. We related this second degradation mode to the migration of the same impurities degrading the top DBR that, when reaching the active region of the laser, induced an increase in the non-radiative recombination rate. In addition to that, we related the two degradation modes to the change in series resistance, which was ascribed to the resistivity increment of the top DBR first and of oxide aperture afterwards.
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| 4. |
- Zenari, M., et al.
(författare)
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Understanding the optical degradation of 845nm micro-transfer-printed VCSILs for photonic integrated circuits
- 2023
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Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 59:4
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Tidskriftsartikel (refereegranskat)abstract
- For the first time we investigate the optical degradation of vertical-cavity silicon-integrated lasers (VCSILs) designed for operation at 845 nm in photonic integrated circuits (PICs). The study is based on the combined electro-optical characterization of VCSIL, submitted to constant-current stress tests at different current levels. The original results obtained within the manuscript indicate that degradation is related to the diffusion of impurities. Remarkably, depending on the region through which these impurities are migrating, the diffusion process affects device characteristics in different ways. During Phase 1 (Ph1), compensating impurities originating from the metal-semiconductor contact cross the top DBR, thus degrading mirror reflectivity, which is rarely observed in the literature, and leading to an increase in the threshold current of the device. As the impurities start reaching the active region we observe the onset of Phase 2 (Ph2), during which both threshold current and sub-threshold slope worsen, due to the increase of the Shockley-Read-Hall recombination rate. This phase is also characterized by a measurable increase in series resistance, which is ascribed to a change in the resistance of the oxide aperture. The identification of the root cause of physical degradation represents a fundamental step for future lifetime improvement of these novel optical sources, which are set to replace conventional solid-state sources in the 0.85 μm communication window.
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| 5. |
- Caut, Alexander, 1994, et al.
(författare)
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Angled Flip-Chip Integration of VCSELs on Silicon Photonic Integrated Circuits
- 2022
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 40:15, s. 5190-5200
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Tidskriftsartikel (refereegranskat)abstract
- An investigation of angled flip-chip integration of a singlemode 850 nm vertical-cavity surface-emitting laser (VCSEL) on a silicon nitride photonic integrated circuit (PIC) is presented. Using numerical FDTD simulations, we consider the conditions under which the VCSEL can be integrated at an angle over a grating coupler with high coupling efficiency and low optical feedback. With both coupling efficiency and feedback decreasing with increasing angle, there is a trade-off. With co-directional coupling, first-order diffraction loss sets in at a critical angle, which further reduces the coupling efficiency. No such critical angle exists for contra-directional coupling. We also experimentally demonstrate angled flip-chip integration of GaAs-based 850 nm single transverse and polarization mode VCSELs over grating couplers on a silicon-nitride PIC. At the output grating coupler, light is either collected by an optical fiber or converted to a photocurrent using a flip-chip integrated GaAs-based photodetector. The latter forms an on-PIC optical link. We measured an insertion loss of 21.9, 17.6 and 20.1 dB with a singlemode fiber, multimode fiber and photodetector over the output grating coupler, respectively.
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| 6. |
- Goyvaerts, Jeroen, et al.
(författare)
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Enabling VCSEL-on-silicon nitride photonic integrated circuits with micro-transfer-printing
- 2021
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Ingår i: Optica. - 2334-2536. ; 8:12, s. 1573-1580
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Tidskriftsartikel (refereegranskat)abstract
- New wavelength domains have become accessible for photonic integrated circuits (PICs) with the development of silicon nitride PICs. In particular, the visible and near-infrared wavelength range is of interest for a range of sensing and communication applications. The integration of energy-efficient III-V lasers, such as vertical-cavity surface-emitting lasers (VCSELs), is important for expanding the application portfolio of such PICs. However, most of the demonstrated integration approaches are not easily scalable towards low-cost and large-volume production. In this work, we demonstrate the micro-transfer-printing of bottom-emitting VCSELs on silicon nitride PICs as a path to achieve this. The demonstrated 850 nm lasers show waveguide-coupled powers exceeding 100 mu W, with sub-mA lasing thresholds and mW-level power consumption. A single-mode laser with a side-mode suppression ratio over 45 dB and a tuning range of 5 nm is demonstrated. Combining micro-transfer-printing integration with the extended-cavity VCSEL design developed in this work provides the silicon nitride PIC industry with a great tool to integrate energy-efficient VCSELs onto silicon nitride PICs.
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| 7. |
- Gustavsson, Johan, 1974, et al.
(författare)
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Silicon integrated 850-nm hybrid vertical-cavity laser for life science applications
- 2017
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Ingår i: VCSEL Day 2017.
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Konferensbidrag (refereegranskat)abstract
- The integration of efficient laser sources on silicon would enable fully integrated silicon photonic circuits with a high degree of functionality and performance complexity for many applications [1]. Different integration concepts have therefore been suggested, where one such technique is the heterogeneous integration of a vertical-cavity laser (VCL), referred to as a hybrid VCL. It is promising as it has potential to offer low drive currents, high modulation bandwidths, and small footprint [2-4]. In-plane emission with waveguide-coupling can be achieved by an intra-cavity waveguide embossed with a weak diffraction grating, as an example [5]. Integration of such short-wavelength laser sources on a silicon-nitride (SiN) waveguide platform on silicon may enable fully integrated silicon photonic circuits for applications not only in short-reach optical interconnects but also in life science and bio-photonics. As a first step in realizing short-wavelength hybrid VCLs with in-plane emission coupled to a SiN waveguide, we have developed a technique to produce high performance 850-nm hybrid VCLs with out-of-plane emission. It is based on adhesive bonding of epitaxial AlGaAs-material onto a dielectric distributed Bragg reflector (DBR) on silicon [6-8]. We have fabricated devices with surface emission having sub-mA threshold current, >2 mW output power, and 25 Gbit/s modulation speed [8]. To be able to demonstrate in-plane emission with SiN waveguide coupling from our hybrid 850-nm VCLs, our next step is to add a SiN waveguide structure with embossed grating on top of the dielectric DBR, before adhesively bonding the AlGaAs-material. So far, based on numerical simulations, we have designed a device that is predicted to yield a slope efficiency of ~0.3 W/A at 25 °C for the light coupled to a single-mode waveguide, while maintaining a sub-mA threshold current for the lasing [9]. This work is supported by the European Union’s Horizon 2020 research and innovation program under grant agreement no. 688519 (PIX4life), the Swedish Foundation for Strategic Research (SSF), and the European FP7-ERC-InSpectra Advanced Grant. References [1] Z. Zhou et al., Light Sci. Appl., vol. 4, no. 11, p. e358, 2015. [2] Y. Tsunemi et al., Opt. Express, vol. 21, no. 23, p. 28685, 2013. [3] J. Ferrara et al., Opt. Express, vol. 23, no. 3, p. 2512, 2015. [4] G.C. Park et al., Laser Photon. Rev., vol. 9, no. 3, p. L11, 2015. [5] D. A. Louderback et al., Electron. Lett., vol. 40, no. 17, p. 1064, 2004. [6] E.P. Haglund et al., Opt. Express, vol. 23, no. 26, p. 33634, 2015. [7] E.P. Haglund et al., IEEE Photon. Technol. Lett., vol. 28, no. 8, p. 856, 2016. [8] E.P. Haglund et al., IEEE J. Sel. Top. Quantum Electron., vol. 23, no. 6, p. 1700109, 2017. [9] S. Kumari et al., Submitted to IEEE Photon. J.,2017.
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| 8. |
- Gustavsson, Johan, 1974, et al.
(författare)
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Silicon-Integrated Hybrid-Vertical-Cavity Lasers for Life Science Applications
- 2017
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Ingår i: 2017 IEEE Photonics Conference. - 9781509065783
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Konferensbidrag (refereegranskat)abstract
- Hybrid 850-nm-wavelength vertical-cavity lasers formed by adhesively bonding AlGaAs-material to a dielectric distributed Bragg reflector on Silicon has experimentally enabled sub-mA threshold current and 25 Gb/s modulation speed. Numerical calculations estimate >0.3 mW/mA slope efficiency for in-plane SiN waveguide coupled light using an intra-cavity grating.
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| 9. |
- Haglund, Emanuel, 1988, et al.
(författare)
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20-Gb/s Modulation of Silicon-Integrated Short-Wavelength Hybrid-Cavity VCSELs
- 2016
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 28:8, s. 856 - 859
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the dynamics of silicon-integrated 850-nm-wavelength hybrid-cavity vertical-cavity surface-emitting lasers (VCSELs). The VCSELs consist of a GaAs-based half-VCSEL attached to a dielectric distributed Bragg reflector on a silicon substrate using ultra-thin divinylsiloxane-bis-benzocyclobutene adhesive bonding. A 5-µm oxide aperture diameter VCSEL, with a small signal modulation bandwidth of 11 GHz, supports data transmission at bit rates up to 20 Gb/s. The modulation bandwidth and the large signal modulation characteristics are found to be impaired by the high thermal impedance.
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| 10. |
- Haglund, Emanuel, 1988, et al.
(författare)
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Dynamic properties of silicon-integrated short-wavelength hybrid-cavity VCSEL
- 2016
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9781510600010 ; 9766
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Konferensbidrag (refereegranskat)abstract
- We present a vertical-cavity surface-emitting laser (VCSEL) where a GaAs-based “half-VCSEL” is attached to a dielectric distributed Bragg reflector on silicon using ultra-thin divinylsiloxane-bis-benzocyclobutene (DVS-BCB) adhesive bonding, creating a hybrid cavity where the optical field extends over both the GaAs- and the Si-based parts of the cavity. A VCSEL with an oxide aperture diameter of 5 μm and a threshold current of 0.4 mA provides 0.6 mW output power at 845 nm. The VCSEL exhibits a modulation bandwidth of 11 GHz and can transmit data up to 20 Gbps.
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