| 1. |
- Dyakov, Sergey, et al.
(författare)
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Optical properties of silicon nanocrystals covered by periodic array of gold nanowires
- 2016
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Ingår i: Physical Review B. - : American Physical Society. - 2469-9950. ; 93:20
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Tidskriftsartikel (refereegranskat)abstract
- Extinction and photoluminescence spectra are experimentally and theoretically studied for a periodic array of gold nanowires deposited on top of a dielectric substrate containing silicon nanocrystals. Quasiguided modes are observed in the substrate resulting in modification of optical properties of silicon nanocrystals. Our calculations of extinction and photoluminescence spectra are in good agreement with experimental results. The periodicity provides a powerful tool for achieving a high photoluminescence outcoupling efficiency of silicon nanocrystals.
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| 2. |
- Lobov, Gleb, et al.
(författare)
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Dynamic manipulation of optical anisotropy of suspended Poly-3-hexylthiophene nanofibers
- 2016
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Ingår i: Advanced Optical Materials. - : Wiley. - 2162-7568 .- 2195-1071. ; 4:10, s. 1651-1656
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Tidskriftsartikel (refereegranskat)abstract
- Poly-3-hexylthiophene (P3HT) nanofibers are 1D crystalline semiconducting nanostructures, which are known for their application in photovoltaics. Due to the internal arrangement, P3HT nanofibers possess optical anisotropy, which can be enhanced on a macroscale if nanofibers are aligned. Alternating electric field, applied to a solution with dispersed nanofibers, causes their alignment and serves as a method to produce solid layers with ordered nanofibers. The transmission ellipsometry measurements demonstrate the dichroic absorption and birefringence of ordered nanofibers in a wide spectral range of 400–1700 nm. Moreover, the length of nanofibers has a crucial impact on their degree of alignment. Using electric birefringence technique, it is shown that external electric field applied to the solution with P3HT nanofibers can cause direct birefringence modulation. Dynamic alignment of dispersed nanofibers changes the refractive index of the solution and, therefore, the polarization of transmitted light. A reversible reorientation of nanofibers is organized by using a quadrupole configuration of poling electrodes. With further development, the described method can be used in the area of active optical fiber components, lab-on-chip or sensors. It also reveals the potential of 1D conducting polymeric structures as objects whose highly anisotropic properties can be implemented in electro-optical applications..
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| 3. |
- Lobov, Gleb, et al.
(författare)
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Electro-optical effects of high aspect ratio P3HT nanofibers colloid in polymer micro-fluid cells
- 2017
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Ingår i: Optics Letters. - : OSA Publishing. - 0146-9592 .- 1539-4794. ; 42:11, s. 2157-2160
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Tidskriftsartikel (refereegranskat)abstract
- This Letter reports the electro-optical (EO) effect of Poly(3-hexylthiophene-2,5-diyl) (P3HT) nanofibers colloid in a polymer micro-fluidic EO cell. P3HT nanofibers are high aspect ratio semiconducting nanostructures, and can be collectively aligned by an external alternating electric field. Optical transmission modulated by the electric field is a manifestation of the electro-optical effect due to high inner crystallinity of P3HT nanofibers. According to our results, the degree of alignment reaches a maximum at 0.6 V/μm of electric field strength, implying a big polarizability value due to geometry and electrical properties of P3HT nanofibers. We believe that one-dimensional crystalline organic nanostructures have a large potential in EO devices due to their significant anisotropy, wide variety of properties, low actuation voltages, and opportunity to be tailored via adjustment of the fabrication process.
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| 4. |
- Lobov, Gleb, et al.
(författare)
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Optical birefringence from P3HT nanofibers in alternating electric field
- 2016
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Ingår i: Optics InfoBase Conference Papers. - : OSA - The Optical Society. - 9781943580194
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Konferensbidrag (refereegranskat)abstract
- AC poling allowing to control the orientation of P3HT nanofibers, result in strong optical birefringence with promising implementation in a novel type of optical modulator, without necessary embedding into any hosting matrix, e.g. liquid crystal.
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| 5. |
- Lobov, Gleb S., et al.
(författare)
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Electric field induced optical anisotropy of P3HT nanofibers in a liquid solution
- 2015
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Ingår i: Optical Materials Express. - : Optical Society of America. - 2159-3930 .- 2159-3930. ; 5:11, s. 2642-2647
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Tidskriftsartikel (refereegranskat)abstract
- The nanofiber morphology of regioregular Poly-3- hexylthiophene (P3HT) is a 1D crystalline structure organized by π - π stacking of the backbone chains. In this study, we report the impact of electric field on the orientation and optical properties of P3HT nanofibers dispersed in liquid solution. We demonstrate that alternating electric field aligns nanofibers, whereas static electric field forces them to migrate towards the cathode. The alignment of nanofibers introduces anisotropic optical properties, which can be dynamically manipulated until the solvent has evaporated. Time resolved spectroscopic measurements revealed that the electro-optical response time decreases significantly with the magnitude of applied electric field. Thus, for electric field 1.3 V ·μm-1 the response time was measured as low as 20 ms, while for 0.65 V ·μm-1 it was 110-150 ms. Observed phenomenon is the first mention of P3HT supramolecules associated with electrooptical effect. Proposed method provides real time control over the orientation of nanofibers, which is a starting point for a novel practical implementation. With further development P3HT nanofibers can be used individually as an anisotropic solution or as an active component in a guest-host system.
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| 6. |
- Lobov, Gleb S., et al.
(författare)
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Electro-optical response of P3HT nanofibers in liquid solution
- 2015
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Ingår i: Asia Communications and Photonics Conference, ACPC 2015. - Washington, D.C. : OSA. - 9781943580064
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Konferensbidrag (refereegranskat)abstract
- AC electric poling introduces in P3HT nanofibers anisotropic electro-optical response and birefringence. Along with birefringence, such material exhibits strong amplitude modulation which makes it more efficient alternative to liquid crystals.
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| 7. |
- Lobov, Gleb S., et al.
(författare)
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Electro-optical response of P3HT nanofibers in liquid solution
- 2015
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Ingår i: Asia Communications and Photonics Conference 2015. - : Optical Society of America. - 9781943580064
-
Konferensbidrag (refereegranskat)abstract
- AC electric poling introduces in P3HT nanofibers anisotropic electro-optical response and birefringence. Along with birefringence, such material exhibits strong amplitude modulation which makes it more efficient alternative to liquid crystals.
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| 8. |
- Lobov, Gleb S., et al.
(författare)
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Size Impact of Ordered P3HT Nanofibers on Optical Anisotropy
- 2016
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Ingår i: Macromolecular Chemistry and Physics. - : John Wiley & Sons. - 1022-1352 .- 1521-3935. ; 217:9, s. 1089-1095
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Tidskriftsartikel (refereegranskat)abstract
- Poly-3-hexylthiophene (P3HT) nanofibers are 1D crystalline structures with semiconductor properties. When P3HT nanofi bers are dispersed in nonconducting solvent, they react to external alternate electric field by aligning along the field lines. This can be used to create layers of ordered nanofi bers and is referred to as alternating current poling method. P3HT nanofi bers with three different size distributions are fabricated, using self-assembly mechanism in marginal solvents, and used for the alignment studies. Anisotropic absorption of oriented 2 mu m long nanofi bers exponentially increases with the magnitude of applied field to a certain asymptotic limit at 0.8 V mu m(-1), while 100-500 nm long nanofi bers respond to electric field negligibly. Effective optical birefringence of oriented 2 mu m long nanofi bers is calculated, based on the phase shift at 633 nm and the average layer thickness, to be 0.41. These results combined with further studies on real-time control over orientation of P3HT nanofi bers in liquid solution or host system are promising in terms of exploiting them in electroabsorptive and electrorefractive applications.
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| 9. |
- Marinins, Aleksandrs, et al.
(författare)
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Air-Suspended SU-8 Strip Waveguides With High Refractive Index Contrast
- 2016
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Ingår i: IEEE Photonics Technology Letters. - : IEEE. - 1041-1135 .- 1941-0174. ; 28:17, s. 1862-1865
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Tidskriftsartikel (refereegranskat)abstract
- Integrated polymer photonics is efficient and cheap solution for many applications, such as optical communications and sensors. Waveguides are basic elements of photonic integrated circuits, and their performance directly influences optical circuit efficiency. However, it is a challenge to develop small footprint polymer waveguides with reasonable losses due to low refractive index comparing to cladding. In this letter, we present free-standing SU-8 waveguides with high refractive index contrast. SiO2 cladding is selectively etched, leaving only air as a cladding material; waveguides are supported by thin pillars. Removal of SiO2 cladding eliminates light leakage to substrate and provides better light confinement. Straight and bending SU-8 waveguides are numerically simulated and experimentally verified lambda = 1550 nm. We also report reduced propagation and bending losses in discussed waveguides.
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| 10. |
- Marinins, Aleksandrs, et al.
(författare)
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All-optical intensity modulation in polymer waveguides doped with si quantum dots
- 2018
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Ingår i: Optics InfoBase Conference Papers. - : Optical Society of America. - 9781557528209
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Konferensbidrag (refereegranskat)abstract
- We demonstrate all-optical intensity modulation in integrated PMMA optical waveguides doped with silicon quantum dots. The 1550 nm probe signal is absorbed by free carriers excited in silicon quantum dots with 405 nm pump light.
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| 11. |
- Marinins, Aleksandrs, et al.
(författare)
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Cylindrical polymer optical waveguides with polarization independent performance
- 2017
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Ingår i: 2017 Conference on Lasers and Electro-Optics, CLEO 2017 - Proceedings. - : OSA Publishing. - 9781943580279 ; , s. 1-2
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Konferensbidrag (refereegranskat)abstract
- Heating of poly(methyl methacrylate) ridge optical waveguides slightly above glass transition temperature minimizes surface roughness and provides cylindrical shape. We experimentally demonstrate propagation loss decrease and polarization insensitivity as a result of waveguide thermal treatment.
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| 12. |
- Marinins, Aleksandrs, 1988-, et al.
(författare)
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Free carrier absorption modulation in polymer waveguides doped with Si nanocrystals
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This work demonstrates all-optical intensity modulation in integrated optical polymer waveguides doped with Si nanocrystals. The modulation here is based on free carrier absorption of 1550 nm probe signal in Si nanocrystals with excited carriers. Optical 405 nm pump was used to increase free carrier concentration. By applying pulsed pump excitation, -1.55 dB deep intensity modulation was achieved in 5 mm long waveguides. The modulation bandwidth is limited to few kHz due to excited carrier relaxation time (τ ~ 100 μs). Demonstrated all-optical reconfigurable polymer waveguides are a promising potential alternative to thermo-optical switches.
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| 13. |
- Marinins, Aleksandrs, et al.
(författare)
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Free-standing su-8 optical waveguides for dense photonic integration
- 2014
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Ingår i: Optics InfoBase Conference Papers. - : OSA - The Optical Society. - 9781943580194
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Konferensbidrag (refereegranskat)abstract
- Air-suspended polymeric waveguides of small footprint suitable for dense packed photonic integrated circuits were developed and evaluated. Low propagation and bending losses at 1550 nm reported. Proposed waveguides are suitable for telecommunications and sensing applications.
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| 14. |
- Marinins, Aleksandrs, et al.
(författare)
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Light Converting Polymer/Si Nanocrystal Composites with Stable 60-70% Quantum Efficiency and their Glass Laminates
- 2017
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Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 9:36, s. 30267-30272
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Tidskriftsartikel (refereegranskat)abstract
- Thiol-ene polymer/Si nanocrystal bulk hybrids were synthesized from alkyl-passivated Si nanocrystal (Si NC) toluene solutions. Radicals in the polymer provided a co-passivation of “dark” Si NCs, making them optically active and leading to a substantial ensemble quantum yield increase. Optical stability over several months was confirmed. The presented materials exhibit the highest photoluminescence quantum yield (~65%) of any solid-state Si NC hybrid reported to date. The broad tunability of thiol-ene polymer reactivity provides facile glass integration, as demonstrated by a laminated structure. This, together with extremely fast polymerization, makes the demonstrated hybrid material a promising candidate for light converting applications.
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| 15. |
- Marinins, Aleksandrs, et al.
(författare)
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Photostable Polymer/Si Nanocrystal Bulk Hybrids with Tunable Photoluminescence
- 2016
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Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 3:9, s. 1575-1580
-
Tidskriftsartikel (refereegranskat)abstract
- Solid polymer/Si nanocrystal bulk nanocomposites were fabricated from solutions of alkene- and hydride-terminated silicon nanocrystals (NCs) in toluene. The photoluminescence peak position of hydride-terminated SiNCs before polymerization was tuned by photoassisted hydrofluoric acid etching. Optical properties of obtained PMMA/NC hybrids, such as quantum yield, luminescence lifetime, and dispersion factor, were evaluated over time. Photostability of these transparent bulk polymer/SiNC hybrids over months was confirmed. The emission covers the visible to near-infrared range with a quantum yield of similar to 30-40% for yellow-red nanocomposites.
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| 16. |
- Marinins, Aleksandrs, 1988-
(författare)
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Polymer Components for Photonic Integrated Circuits
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Optical polymers are a subject of research and industry implementation for many decades. Optical polymers are inexpensive, easy to process and flexible enough to meet a broad range of application-specific requirements. These advantages allow a development of cost-efficient polymer photonic integrated circuits for on-chip optical communications. However, low refractive index contrast between core and cladding limits light confinement in a core and, consequently, integrated polymer device miniaturization. Also, polymers lack active functionality like light emission, amplification, modulation, etc. In this work, we improved a performance of integrated polymer waveguides and demonstrated active waveguide devices. Also, we present novel Si QD/polymer optical materials.In the integrated device part, we demonstrate optical waveguides with enhanced performance. Decreased radiation losses in air-suspended curved waveguides allow low-loss bending with radii of only 15 µm, which is far better than >100 µm for typical polymer waveguides. Another study shows a positive effect of thermal treatment on acrylate waveguides. By heating higher than polymer glass transition temperature, surface roughness is reflown, minimizing scattering losses. This treatment method enhances microring resonator Q factor more than 2 times. We also fabricated and evaluated all-optical intensity modulator based on PMMA waveguides doped with Si QDs.We developed novel hybrid optical materials. Si QDs are encapsulated into PMMA and OSTE polymers. Obtained materials show stable photoluminescence with high quantum yield. We achieved the highest up to date ~65% QY for solid-state Si QD composites. Demonstrated materials are a step towards Si light sources and active devices.Integrated devices and materials presented in this work enhance the performance and expand functionality of polymer PICs. The components described here can also serve as building blocks for on-chip sensing applications, microfluidics, etc.
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| 17. |
- Marinins, Aleksandrs, 1988-, et al.
(författare)
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Thermal reflow engineered cylindrical polymer waveguides for optical interconnects
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Integrated polymer photonics brings low cost and high fabrication flexibility to optoelectronic industry. However, this platform needs to overcome several issues to be efficient enough for practical applications. In this work, we experimentally demonstrate a decrease of propagation losses and polarization sensitivity of polymer waveguide-based devices as a result of thermal treatment. Heating of poly(methyl methacrylate) (PMMA) strip optical waveguides above the glass transition temperature initiates a waveguide surface reflow due to a decrease of a polymer viscosity and surface tension energy. This results in a decrease of surface roughness and shape change from rectangular to cylindrical; thus, scattering losses and polarization sensitivity are minimized.
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| 18. |
- Marinins, Aleksandrs, et al.
(författare)
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Thermal Reflow Engineered Cylindrical Polymer Waveguides for Optical Interconnects
- 2018
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Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers Inc.. - 1041-1135 .- 1941-0174. ; 30:5, s. 447-450
-
Tidskriftsartikel (refereegranskat)abstract
- Integrated polymer photonics brings low cost and high fabrication flexibility to optoelectronic industry. However, this platform needs to overcome several issues to be effective enough for practical applications. In this letter, we experimentally demonstrate a decrease of propagation losses and polarization sensitivity of polymer waveguide-based devices as a result of thermal treatment. Heating of poly(methyl methacrylate) strip optical waveguides above the glass transition temperature initiates a waveguide surface reflow due to a decrease of the polymer viscosity and surface tension energy. This results in a decrease of surface roughness and shape change from rectangular to cylindrical. Thus, scattering losses and polarization sensitivity are minimized.
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| 19. |
- Ostrovskis, Armands, et al.
(författare)
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170 Gbaud On-Off-Keying SiP Ring Resonator Modulator-based Link for Short-Reach Applications
- 2024
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Ingår i: 2024 IEEE Silicon Photonics Conference, SiPhotonics 2024 - Proceedings. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate a record 170 Gbaud on-off keying C-band silicon photonics ring resonator modulator-based transmitter with performance below the 6.7% overhead HD-FEC threshold after optical back-to-back and transmission over 100 meters of single mode fiber.
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| 20. |
- Ozolins, Oskars, et al.
(författare)
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High-Baudrate Silicon Photonics Ring Resonator and Mach-Zehnder Modulators for Short-Reach Applications
- 2023
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Ingår i: 2023 23rd International Conference on Transparent Optical Networks, ICTON 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- Silicon photonics (SiP) is a key enabling technology for high-baudrate communication. It is a key technology for future 800 Gbps and 1.6 Tbps solutions to meet the ever-increasing demands. The 800G pluggable multi-source agreement (MSA) suggests that intensity-modulated direct-detection (IM/DD) is the most sustainable way forward [1]. The high operational bandwidth of each transceiver component is essential. An ultra-compact SiP slow light modulator with record-high bandwidth of 110 GHz shows the potential [2]. Therefore, both multilevel pulse amplitude modulation (PAM) and on-off keying (OOK) should be considered. SiP offers excellent production yield and has a substantial role in optical interconnects. SiP ring resonator modulators (RRM) have unique advantages like a small footprint, simple driver configuration, low power consumption, and suitability for multichannel applications. On the other hand, the SiP Mach-Zehnder modulator (MZM) offers differential drive benefits.
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| 21. |
- Ozolins, Oskars, et al.
(författare)
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High-Baudrate Silicon Photonics Ring Resonator Modulators for Short-Reach Applications
- 2023
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Ingår i: 2023 Asia Communications and Photonics Conference/2023 International Photonics and Optoelectronics Meetings, ACP/POEM 2023. - : Institute of Electrical and Electronics Engineers (IEEE).
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate up to 160 Gbaud on-off keying with first ring resonator modulator and up to 128 Gbaud on-off keying with second ring resonator modulator. Both modulators achieve performance below 6.25% OH HD-FEC threshold.
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| 22. |
- Popov, Sergei, et al.
(författare)
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Polymer photonics and nano-materials for optical communication
- 2018
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Ingår i: 2018 17th Workshop on Information Optics, WIO 2018. - : Institute of Electrical and Electronics Engineers Inc.. - 9781538660133
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Konferensbidrag (refereegranskat)abstract
- Polymer materials offer process compatibility, design flexibility, and low cost technology as a multi-functional platform for optical communication and photonics applications. Design and thermal reflowing technology of low loss polymer waveguides, as well as demonstration of transparent wood laser are presented in this paper.
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| 23. |
- Sychugov, Ilya, et al.
(författare)
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Luminescent silicon nanocrystals as downconverters for photovoltaic and lighting applications
- 2016
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Ingår i: Asia Communications and Photonics Conference, ACP. - : OSA - The Optical Society.
-
Konferensbidrag (refereegranskat)abstract
- Nanocrystals offer new functionalities for optoelectronics. Ensemble and single-dot measurements of chemically-synthesized silicon nanocrystals revealed high quantum yield, narrow homogeneous linewidth, and large Stokes shift, confirming application feasibility for these non-toxic and abundant material nanoparticles. Asia Communications and Photonics Conferene (ACP)
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| 24. |
- Vasileva, Elena, et al.
(författare)
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Optimization of optical gain in composite materials containing Rh6G dye and gold nanoparticles
- 2015
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Ingår i: Asia Communications and Photonics Conference, ACPC 2015. - Washington, D.C. : OSA. - 9781943580064
-
Konferensbidrag (refereegranskat)abstract
- The existence of metal nanoparticles in a dye material can lead not only to quenching or enhancement of dye luminescence, or random lasing action, but also to the change of the fundamental material characteristic as optical gain.
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| 25. |
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| 26. |
- Zhao, Yichen, et al.
(författare)
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Electrical Field Induced Alignment of P3HT Nanofibers
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Abstract: Poly 3-hexylthiophene (P3HT) is one of the most studied conjugated polymers for organic solar cell applications due to its light weight, flexible processing methods and low cost fabrication. However, the hole mobility in P3HT is still relatively low compared to that of the inorganic semiconductors, which is one of the main challenges to achieve better performance of organic solar cells. The P3HT nanofibers with aligned by inducing an external electric field have been studied to improve the hole mobility in P3HT nanofibers. Here we present an AC electric field (1.3 V/µm, 50 Hz) induced alignment of P3HT nanofibers with two different lengths. The optical absorption spectra of aligned nanofibers were measured under different polarizations of incident light. The longer nanofibers showed higher dichroic raitos than that of shorter nanofibers, revealing a better alignment pattern. The photoconductivity of non-aligned and aligned P3HT nanofibers were measured and compared, where the aligned P3HT nanofibers showed a ~270% higher dark current than that of non-aligned sample. Moreover, the current measured under the illumination showed ~110% enhancement in the aligned P3HT nanofibers while only ~70% enhancement was obseved in non-aligned nanofibers, revealing that the alignment process have the potential to improve the mobility for optoelectronic applications.
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