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| 2. |
- Gustafsson, Oscar, et al.
(författare)
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Photoluminescence photoresponse from InSb/InAs-based quantum dot structures
- 2012
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 20:19, s. 21264-71
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Tidskriftsartikel (refereegranskat)abstract
- InSb-based quantum dots grown by metal-organic vapor-phase epitaxy (MOVPE) on InAs substrates are studied for use as the active material in interband photon detectors. Long-wavelength infrared (LWIR) photoluminescence is demonstrated with peak emission at 8.5 μm and photoresponse, interpreted to originate from type-II interband transitions in a p-i-n photodiode, was measured up to 6 μm, both at 80 K. The possibilities and benefits of operation in the LWIR range (8-12 μm) are discussed and the results suggest that InSb-based quantum dot structures can be suitable candidates for photon detection in the LWIR regime.
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| 3. |
- Hällstig, Emil, et al.
(författare)
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Retrocommunication utilizing electroabsorption modulators and non-mechanical beam steering
- 2005
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Ingår i: Optical Engineering. - : SPIE-Intl Soc Optical Eng. - 0091-3286 .- 1560-2303. ; 44:4, s. 045001-
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Tidskriftsartikel (refereegranskat)abstract
- A novel retrocommunication link utilizing reflective multiplequantum well (MQW) optical modulators and nonmechanical beamsteering and tracking is demonstrated. Large aperture reflective MQWmodulators using AlGaAs/GaAs are optimized and manufactured. Themodulators exhibit a contrast ratio larger than 4:1 and a modulationbandwidth of 10 MHz. Nonmechanical beam steering and tracking arestudied using nematic liquid crystal (NLC) spatial light modulators(SLMs). The communication link is comprised of a retromodulating arraywith four MQW modulators and a transceiver using a NLC SLM for beamsteering and tracking. Transfer of audio, real-time image data and pseudorandombit sequences over 100-m range while tracking the movingretromodulator is shown. The link is capable of transferring data at approximately8 Mbps.
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| 4. |
- Junique, Stephane, et al.
(författare)
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A Modulating retro-reflector for free-space optical communication
- 2006
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 18:1, s. 85-87
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Tidskriftsartikel (refereegranskat)abstract
- We present modeling of a modulating retro-reflector for free-space optical communication, composed of a reflective resonant-cavity modulator and a corner cube. Although resonant-cavity modulators are sensitive to the angle of incidence of the light beam, we show that with the right geometrical arrangement, the field of view can be more than ten-fold that of the modulator. The modeling is validated by experimental data using a corner cube and a 14 x 14 mm(2) multiple quantum-well modulator.
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| 5. |
- Junique, Stephan, et al.
(författare)
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GaAs-based multiple-quantum-well spatial light modulators fabricated by a wafer-scale process
- 2005
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 44:9, s. 1635-1641
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Tidskriftsartikel (refereegranskat)abstract
- The design, fabrication, and characterization of large, two-dimensional multiple-quantum-well modulator arrays are presented. Such arrays present a speed advantage compared with competing technologies such as liquid crystals and micromirrors, which are intrinsically limited to the kilohertz range. We discuss the design compromises to reach high-contrast, low-voltage swing optical structures compatible with complementary metal-oxide semiconductor-based integrated circuits and present experimental results. Contrast ratio of 5:1 (limited by the fill factor), variations in uniformity below 1 nm, and frame rates in excess of 10 kHz are demonstrated. Technology maturity for volume production is also discussed.
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| 6. |
- Junique, Stephane, et al.
(författare)
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Large–area, three–state, binary amplitude and binary phase vertical–cavity multiple quantum well electroabsorption modulator
- 2007
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Ingår i: Optics Express. - 1094-4087. ; 15:14, s. 8566-8575
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Tidskriftsartikel (refereegranskat)abstract
- We present the design and characterization of a large optical modulator array based on GaAs multiple quantum wells for amplitude and phase modulation. The device shows two high-reflectance states with a phase difference close to 180 degrees for use as a binary phase modulator. It also shows a third, low-reflectance state for use as an amplitude modulator. It is segmented into 64 pixels in a single row, giving an active area of 2mm x 5mm. We discuss the device performance as a ternary binary amplitude and binary phase modulator, including contrast ratio and uniformity, and show that a voltage swing of only 5V is needed to drive it.
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| 7. |
- Junique, Stéphane, et al.
(författare)
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Multiple quantum well spatial light modulators design-fabrication-characterization
- 2001
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - San Diego, CA : SPIE. ; , s. 62-71
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Konferensbidrag (refereegranskat)abstract
- Multiple quantum well spatial light modulators (MQW SLMs) are promising devices for future high-speed applications. We present results obtained with a single-pixel amplitude modulator. We discuss the status of our work on a 128x—128-pixel ternary SLM. This SLM will run at 10 kHz and have one low-reflectance level and two high reflectance levels with a phase difference of Ï€. We also present a study of the relation between the coding domain and the structural design of modulators.
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| 8. |
- Noharet, Bertrand, et al.
(författare)
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A compact LIBS system for industrial applications
- 2015
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Ingår i: Proceedings of SPIE. - : SPIE. - 9781628414592
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Konferensbidrag (refereegranskat)abstract
- In recent years, laser-induced breakdown spectroscopy (LIBS) has been established as a promising analytical tool for online chemical analysis. The emitted light spectrum is analyzed for instantaneous determination of the elemental composition of the sample, enabling on-line classification of materials. Two major strengths of the technique are the possibilities to perform both fast and remote chemical analysis to determine the elemental composition of the samples under test. In order to reduce the size of LIBS systems, the use of a compact Q-switched diode-pumped solid-state laser (DPSSL) in a LIBS system is evaluated for the industrial sorting of aluminium alloys. The DPSSL, which delivers 150μJ pulses of high beam quality at more than 7KHz repetition rate, provides irradiance on the target that is appropriate for LIBS measurements. The experimental results indicate that alloy classification and quantitative analysis are possible on scrap aluminium samples placed 50 cm apart from the focusing and collecting lenses, without sample preparation. Similar calibration curves and limits of detection are obtained for traditional high-energy low-frequency flashlamp-pumped and low-energy high-frequency diode-pumped lasers, showing the applicability of compact diode-pumped lasers for industrial LIBS applications.
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| 9. |
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| 10. |
- Noharet, Bertrand, et al.
(författare)
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Multiple quantum well spatial light modulators for correlation-based processors
- 2001
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Ingår i: Proceedings of SPIE. - 0819441236 ; , s. 314-364
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Konferensbidrag (refereegranskat)abstract
- To be competitive with their electronic counterparts, correlation-based optical processors require very fast spatial light modulators (SLMs) that can perform simultaneously phase and amplitude modulation. Owing to their ultra-high speed, multiple quantum well (MQW) SLMs have been early identified as very good candidates. However, the coding domain of MQW SLMs is not widely known. We present here a study of available coding domains of MQW SLMs. We demonstrate that pure amplitude modulation, ternary [4, 0, +1) modulation and quaternary to, +1, e(i2pi/3), e(i4pi/3)) modulation are examples of coding domains that can be achieved by tuning a few parameters in the design of Fabry-Perot MQW modulators. We show that ternary and quaternary filters provide much better results than binary filters for the recognition of objects embedded in highly cluttered noise. Finally, we present a technique, the time-averaged pseudo-random encoding technique, which enables encoding of any complex filter onto a quaternary modulator. Combined with the time-averaged pseudo-random encoding technique, MQW SLMs may pave the way to the development of new optoelectronic correlator systems with improved speed and accuracy performance.
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