| 1. |
- Höglund, Linda, 1974-, et al.
(författare)
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Quantum dots-in-a-well infrared photodetectors for long wavelength infrared detection
- 2006
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Ingår i: Proceedings of SPIE. - Bellingham, Wash. : SPIE - International Society for Optical Engineering. - 9780819464996 ; 6401, s. 1-640109
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Konferensbidrag (refereegranskat)abstract
- We report on a quantum dots-in-a-well infrared photodetector (DWELL QDIP) grown by metal organic vapor phase epitaxy. The DWELL QDIP consisted of ten stacked InAs/In0.5Ga0.85As/GaAs QD layers embedded between n-doped contact layers. The density of the QDs was about 9 × 10 10 cm-2 per QD layer. The energy level structure of the DWELL was revealed by optical measurements of interband transitions, and from a comparison with this energy level scheme the origin of the photocurrent peaks could be identified. The main intersubband transition contributing to the photocurrent was associated with the quantum dot ground state to the quantum well excited state transition. The performance of the DWELL QDIPs was evaluated regarding responsivity and dark current for temperatures between 15 K and 77 K. The photocurrent spectrum was dominated by a LWIR peak, with a peak wavelength at 8.4 μm and a full width at half maximum (FWHM) of 1.1 μm. At an operating temperature of 65 K, the peak responsivity was 30 mA/W at an applied bias of 4 V and the dark current was 1.2×10-5 A/cm2. Wavelength tuning from 8.4 μm to 9.5 μm was demonstrated, by reversing the bias of the detector.
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| 2. |
- Parola, Stephane, et al.
(författare)
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Hybrid materials for optical limiting applications
- 2006
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Ingår i: Optical Materials in Defence Systems Technology III. - Stockholm, Sweden : SPIE-INT SOC OPTICAL ENGINEERING. - 9780819464996 ; , s. U71-U78
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Konferensbidrag (refereegranskat)abstract
- Optical limiting materials are developed for applications in protection of optical sensors against laser aggressions. We have studied functionalised macrocycles (thiacalixarenes) and alkynylplatinum(H) derivatives for optical limiting applications. Glass materials based on alkynylplatinum(H) derivatives and macrocycles were prepared through the sol-gel process. The molecular species were grafted to the matrix in order to maximise the concentration and the stability of the final solid-state material. The glass materials were cut and polished to approximately 1.5 mm. The glass materials show broadband optical limiting in the visible wavelength region, for nanosecond laser pulses.
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| 3. |
- Thylen, Lars
(författare)
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Materials R&D as enablers for quantum leaps in photonics device development and performance
- 2006
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Ingår i: Optical Materials in Defence Systems Technology III. - BELLINGHAM, WA : SPIE-INT SOC OPTICAL ENGINEERING. - 9780819464996 ; , s. U5-U7
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Konferensbidrag (refereegranskat)abstract
- Progress in photonics and indeed in many areas of science and technology has in many cases been closely linked to development in materials. This development has in some cases been initiated by theoretical considerations and requirements formulation, in other cases novel materials have opened up unexpected applications. Examples of the former are given, where materials meeting certain requirements would lead to quantum leaps in device performance.
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| 4. |
- Vamvounis, George, et al.
(författare)
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Formation and properties of isoporous films composed of polymer semiconductors
- 2006
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Ingår i: Optical Materials in Defence Systems Technology III. - BELLINGHAM, WA : SPIE-INT SOC OPTICAL ENGINEERING. - 9780819464996 ; , s. U64-U70
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Konferensbidrag (refereegranskat)abstract
- Ordered hexagonal arrays of isoporous films prepared from poly(9,9'-dihexylfluorene) and polystyrene grafted silica nanoparticles (Si-graft-PS) are presented. These close packed arrays were formed in areas of many square millimeters. The pore size varied from 2.9 - 8.5 mu m, depending on the concentration of Si-graft-PS and the processing conditions. Solid state photoluminescence resulted in a significant red shift of up to 30 nm in these films compared to conventional processing techniques. These differences are attributed to induced aggregation of the polymers caused by polymer- solvent interactions. Interfacial properties were investigated, and it was found that hydrophobic surfaces (contact angles of up to 129 degrees) were prepared because of high surface roughness. These ordered porous polymer films may find use in microelectronic and bio- and/or chemical sensor applications.
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| 5. |
- Westlund, Robert, et al.
(författare)
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Multi-functionalized platinum(II) acetylides for optical power limiting
- 2006
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Ingår i: Optical Materials in Defence Systems Technology III. - : SPIE-INT SOC OPTICAL ENGINEERING. - 9780819464996 ; , s. U87-U94
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Konferensbidrag (refereegranskat)abstract
- Preliminary results on the optical power limiting properties of platinum(II) acetylides containing triazole units are presented. It is shown that the triazole units give a positive contribution to the limiting abilities of the platinum(H) acetylide and that this modified chromophore could have potential use in sensor protection devices. Moreover, this paper discusses how the versatile building block 2,2-bis(methylol)propionic acid (bis-MPA) can be used advantageously to functionalize nonlinear optical (NLO) platinum(H) acetylides. The bis-MPA units can be used to prepare dendritic substituents offering site isolation to the chromophore leading to improved clamping. The bis-MPA functionalization also improves the solubility of the platinum(H) acetylides in many organic solvents. The preparation of solid-state optical power limiters, where the NLO chromophore is inserted in an optically transparent matrix, is addressed. Again, the bis-MPA unit can be employed to increase the number of accessible end-groups to which matrix-compatible species can be attached. It is concluded that the hydroxy-functional platinum(II) acetylides can be modified to fit almost any matrix, organic or inorganic. Finally, depending on functionalization, it is possible to prepare doped glasses where the chromophore is either embedded in the matrix, or covalently bonded to the matrix.
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| 6. |
- Ågren, Hans, et al.
(författare)
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Multiphysics modelling of optical materials
- 2006
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Ingår i: Optical Materials in Defence Systems Technology III. - BELLINGHAM, WA : SPIE-INT SOC OPTICAL ENGINEERING. - 9780819464996 ; , s. U8-U24
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Konferensbidrag (refereegranskat)abstract
- We review multiphysics modeling of pulse propagation in non-linear media and highlight some recent applications on optical materials containing organic or organometallic chromophores.
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