| 1. |
- Chacinski, Marek, et al.
(författare)
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Single-mode 1.27 μm InGaAs vertical cavity surface-emitting lasers with temperature-tolerant modulation characteristics
- 2005
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 86:21, s. 211109-1-211109-3
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic performance of InGaAs/GaAs 1.27 μ m single-mode vertical cavity surface emitting lasers (VCSELs) is presented. In order to reach such a long wavelength, the devices utilize highly strained double-quantum wells and a large detuning between the material gain peak and cavity resonance. It is found that the large detuning improves the temperature stability of both static and modulation characteristics. A resonance frequency of 7.8-9.5 GHz and optical power of 0.30 mW in fiber was maintained throughout the investigated temperature range of 20-90 ° C. The intrinsic response of the device suggests that long-wavelength InGaAs/GaAs VCSELs have the potential to be used as low cost uncooled optical transmitters at 10 Gbit/s. © 2005 American Institute of Physics. © 2005 American Institute of Physics.
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| 2. |
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| 3. |
- Hammar, Mattias, et al.
(författare)
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1.3-mu m InGaAs vertical-cavity surface-emitting lasers
- 2005
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Ingår i: 2005 IEEE LEOS Annual Meeting Conference Proceedings (LEOS). - 0780392175 ; , s. 396-397
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Konferensbidrag (refereegranskat)abstract
- We report on the fabrication and performance of N-free InGaAs/GaAs 1.3-mu m range vertical-cavity surface-emitting lasers (VCSELs). Using optimized quantum-well (QW) growth conditions in combination with negative gain-cavity tuning, high-performance VCSELs with emission wavelength up to 1300 nm are realized. The performance figures include mA-range threshold currents, mW-range singlemode output power, continuous-wave operation up to 140 degrees C and 10 Gbit/s data transmission.
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| 4. |
- Hoglund, Linda, et al.
(författare)
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Type-II InAs/GaSb superlattices for dual color infrared detection
- 2017
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Ingår i: QUANTUM SENSING AND NANO ELECTRONICS AND PHOTONICS XIV. - : SPIE-INT SOC OPTICAL ENGINEERING. - 9781510606647
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Konferensbidrag (refereegranskat)abstract
- Midwave-midwave dual color detection has been successfully demonstrated by using pixel filters fabricated on top of InAs/GaSb focal plane arrays (FPAs). The pixel filters used in these FPAs were designed to transmit infrared radiation in the 3.5 - 4.1 mu m wavelength region and to completely block light shorter than 3.5 mu m. By comparing the signals of filtered and unfiltered pixels, excellent contrast between the two bands were obtained. This design concept offers a great flexibility to tailor the transmission window to any wavelength range within the 3-5 mu m wavelength region. In particular, this dual color detector concept has been used for gas detection of volatile organic compounds which have main absorption peaks at 3.3 mu m.
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| 5. |
- Karim, Amir, et al.
(författare)
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Characterization of InAs/GaSb type€II superlattice photodiodes for mid€wave IR with different mesa sidewall passivation schemes
- 2012
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Ingår i: Physica Status Solidi. C, Current topics in solid state physics. - : Wiley. - 1610-1634 .- 1610-1642. ; c9:7, s. 1690-2
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Tidskriftsartikel (refereegranskat)abstract
- We report on the electrical material characterization of InAs/GaSb type-II superlattice (T2SL) mid-wave infrared (MWIR) photodiodes with different passivation schemes on the mesa-sidewalls with significant differences in the resulting low temperature dark currents. Devices fabricated by dry etching passivated with polymerized photoresist, show orders of magnitude lower dark currents as compared to unpassivated devices. The mesa side walls were examined using high resolution transmission electron microscopy (HRTEM) with a special focus on the interface between the superlattice material the dielectric passivation. Material analysis on nanometer scale at the mesa sidewall interface was performed using energy dispersive X-ray (EDX) spectrometry. EDX line scans were obtained from interfaces for different passivated unpassivated devices, using the highly focused electron beam in TEM, to investigate the chemical compositions. The unpassivated photoresist-passivated mesas, with different electrical properties, revealed different sidewall morphologies compositions. An oxygen containing layer was observed in photoresist-passivated devices covering the whole mesa sidewall. We think this plays a role in reducing surface leakage dark current. In HR-TEM the mesa sidewall topography reveals preferential etching of one superlattice component as previously observed. Nevertheless, the dielectric material covers the sidewall uniformly.
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| 6. |
- Malm, Hedda, et al.
(författare)
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Recent developments in type-II superlattice detectors at IRnova AB
- 2012
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Ingår i: INFRARED TECHNOLOGY AND APPLICATIONS XXXVIII, PTS 1 AND 2. - : SPIE-INT SOC OPTICAL ENGINEERING. - 9780819490315
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Konferensbidrag (refereegranskat)abstract
- A mid wave infrared type-II superlattice focal plane array with 320x256 pixels, 30 mu m pitch and 90 % fill factor was fabricated in house, using a conventional homojunction p-i-n photodiode design and the ISC9705 readout circuit. High-quality imaging up to 110 K is demonstrated with the substrate fully removed. The absorber is 2 mu m thick, and no antireflection coating was used, so there is still room for significant improvement of the quantum efficiency, which is in the 40 % range. Studies of the dark current vs. temperature behavior indicate that the device is limited by Shockley-Read-Hall generation from the depletion region. The activation energy of this dark current component is 0.13 eV, suggesting an unidentified recombination center positioned halfway into the 0.24 eV bandgap. Furthermore, we report on detectors with 100 % cut-off at 13 mu m. The dark current density at 60 K and -50 mV bias is 2x10(-4) A/cm(2). Quantum efficiency, NETD and BLIP temperature are also calculated. Position-sensitive photocurrent measurements on mesa-etched superlattice material were made at low temperatures using a focused laser spot. The lateral diffusion length for holes was extracted and is reported.
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| 7. |
- Marcks von Würtemberg, Rickard, et al.
(författare)
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1.3 μm InGaAs vertical-cavity surface-emitting lasers with mode filter for single mode operation
- 2004
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 85:21, s. 4851-4853
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Tidskriftsartikel (refereegranskat)abstract
- We report on the performance and analysis of 1.3 mum range InGaAs/GaAs vertical-cavity surface-emitting lasers (VCSELs) with an integrated mode filter consisting of a patterned silicon layer on the top distributer Bragg reflector. In this way, 1 mW of single mode power is obtained from a device with a wavelength of 1265 nm and a threshold current of 2.6 mA at room temperature. An effective index model is used to extract the internal and external losses of the VCSEL structure and to predict the modal losses with and without mode filter, thereby providing a useful design tool for single mode VCSELs.
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| 8. |
- Marcks von Würtemberg, Rickard, et al.
(författare)
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A novel electrical and optical confinement scheme for surface emitting optoelectronic devices
- 2006
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Ingår i: WORKSHOP ON OPTICAL COMPONENTS FOR BROADBAND COMMUNICATION. - BELLINGHAM, WA : SPIE-INT SOC OPTICAL ENGINEERING. - 0819464457 ; , s. 63500J-1-63500J-10
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Konferensbidrag (refereegranskat)abstract
- A novel electrical and optical confinement scheme for surface emitting optoelectronic devices is presented. The scheme is based on epitaxial regrowth of a pnp current blocking layer structure around a mesa etched in the vertical cavity region of the device. The lateral size and orientation of the mesa is defined lithographically and dry etching is used to create vertical mesa sidewalls. By orienting the mesa sidewalls in certain crystallographic directions, it is possible to selectively grow a current blocking pnp layer structure on the exposed n-type lower cladding layer of the cavity whithout obstructing the electrical injection into the active region. The concept is evaluated in 1.2-mu m GaAs-based light emitting diodes with InGaAs quantum wells. This type of structure can easily be used as the amplifying region of a vertical cavity laser, providing a good alternative to selective oxidation confinement.
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| 9. |
- Marcks von Würtemberg, Rickard, 1973-
(författare)
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Design and fabrication of long wavelength vertical cavity lasers on GaAs substrates
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Vertical cavity surface emitting lasers (VCSELs) are today a commodity on the short wavelength laser market due to the ease with which they are manufactured. Much effort has in the last decade been directed towards making long wavelength VCSELs as successful in the marketplace. This has not been achieved due to the much more difficult fabrication technologies needed for realising high performance long wavelength VCSELs. At one point, GaInNAs quantum wells gain regions grown on GaAs substrates seemed to be the solution as it enabled all-epitaxial VCSELs that could make use of high contrast AlGaAs-based distributed Bragg reflectors (DBRs) as mirrors and lateral selective oxidation for optical and electrical confinement, thereby mimicking the successful design of short wavelength VCSELs. Although very good device results were achieved, reproducible and reliable epitaxial growth of GaInNAs quantum wells proved difficult and the technology has not made its way into high-volume production. Other approaches to the manufacturing and material problems have been to combine mature InP-based gain regions with high contrast AlGaAs-based DBRs by wafer fusion or with high contrast dielectric DBRs. Commonly, a patterned tunnel junction provides the electrical confinement in these VCSELs. Excellent performance has been achieved in this way but the fabrication process is difficult. In this work, we have employed high strain InGaAs quantum wells along with large detuning between the gain peak and the emission wavelength to realize GaAs-based long wavelength VCSELs. All-epitaxial VCSELs with AlGaAs-based DBRs and lateral oxidation confinement were fabricated and evaluated. The efficiency of these VCSELs was limited due to the optical absorption in the doped DBRs. To improve the efficiency and manufacturability, two novel optical and electrical confinement schemes based on epitaxial regrowth of current blocking layers were developed. The first scheme is based on a single regrowth step and requires very precise processing. This scheme was therefore not developed beyond the first generation but single mode power of 0.3 mW at low temperature, -10ºC, was achieved. The second scheme is based on two epitaxial regrowth steps and does not require as precise processing. Several generations of this design were manufactured and resulted in record high power of 8 mW at low temperature, 5ºC, and more than 3 mW at high temperature, 85ºC. Single mode power was more modest with 1.5 mW at low temperature and 0.8 mW at high temperature, comparable to the performance of the single mode lateral oxidation confined VCSELs. The reason for the modest single mode power was found to be a non-optimal cavity shape after the second regrowth that leads to poor lateral overlap between the gain in the quantum wells and the intensity of the optical field.
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| 10. |
- Marcks von Würtemberg, Rickard, et al.
(författare)
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Fabrication and performance of 1.3-μm vertical cavity surface emitting lasers with InGaAs quantum well active regions grown on GaAs substrates
- 2004
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5443, s. 229-239
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Tidskriftsartikel (refereegranskat)abstract
- We describe the development of long-wavelength InGaAs/GaAs vertical-cavity surface emitting lasers (VCSELs). Using highly strained double-quantum wells (DQWs) in combination with negative gain-cavity detuning we have been able to realise such VCSELs with emission wavelength up to 1300 nm. High-performance device characteristics include mW-range output power, mA-range threshold currents, 10 Gbit/s data transmission and very good temperature stability with continuous-wave operation up to at least 140degreesC. Singlemode emission is realised using an integrated mode filter consisting of a patterned silicon layer on the out-coupling mirror surface, yielding output power and threshold currents for 1270-nm devices of 1.2 - 0.5 mW and 2.3 - 0.6 mA, respectively, over a temperature interval of 10 - 140degreesC. Multimode devices have been found to deliver more than 2 mW at 1290 nm. Preliminary lifetime measurements do not reveal any intrinsic reliability problems related to the highly strained quantum wells.
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