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| 4. |
- Akram, Nadeem, et al.
(författare)
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Design optimization of InGaAsP-InGaAlAs 1.55 mu;m strain-compensated MQW lasers for direct modulation applications
- 2004
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Ingår i: Indium Phosphide and Related Materials, 2004. 16th IPRM. 2004 International Conference on. - : IEEE. - 0780385950 ; , s. 418-421
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Konferensbidrag (refereegranskat)abstract
- A comprehensive simulation study of InGaAsP (well)/InGaAlAs(barrier) 1.55 mu;m strain-compensated MQW lasers is presented. For MQWs, a uniform vertical distribution of holes is achieved due to a reduced effective hole confinement energy by optimizing the bandgap and strain of the barriers and p-doping in the active region. Some preliminary results are also presented for the manufactured lasers using these QWs indicating a good material platform.
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| 5. |
- Akram, Nadeem, 1971-, et al.
(författare)
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Experimental characterization of high-speed 1.55 mu m buried heterostructure InGaAsP/InGaAlAs quantum-well lasers
- 2009
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Ingår i: Journal of the Optical Society of America. B, Optical physics. - 0740-3224 .- 1520-8540. ; 26:2, s. 318-327
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Tidskriftsartikel (refereegranskat)abstract
- Detailed experimental characterization is performed for 1550 nm semi-insulating regrown buried heterostructure Fabry-Perot (FP) lasers having 20 InGaAsP/InGaAlAs strain-balanced quantum wells (QWs) in the active region. Light-current-voltage performance, electrical impedance, small-signal response below and above threshold, amplified spontaneous emission spectrum below threshold and relative intensity noise spectrum are measured. Different laser parameters such as external differential quantum efficiency eta(d), background optical loss alpha(i), K-factor, D-factor, characteristic temperature T-0, differential gain dg/dn, gain-compression factor epsilon, carrier density versus current, differential carrier lifetime tau(d), optical gain spectrum below threshold, and chirp parameter alpha are extracted from these measurements. The FP lasers exhibited a high T-0 (78-86.5 degrees C) and very high-resonance frequency (23.7 GHz). The results indicate that appropriately designed lasers having a large number of InGaAsP well/InGaAlAs barrier QWs with shallow valence-band discontinuity can be useful for un-cooled high-speed direct-modulated laser applications.
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| 6. |
- Akram, Nadeem, 1971-, et al.
(författare)
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High-Speed Performance of 1.55 µm Buried Hetero-Structure Lasers with 20 InGaAsP/InGaAlAs Quantum-Wells
- 2006
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Ingår i: 2006 European Conference on Optical Communications Proceedings, ECOC 2006. - : IEEE. - 9782912328397 ; , s. 1-2
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Konferensbidrag (refereegranskat)abstract
- 1550 nm re-grown FP lasers having 20 InGaAsP/InGaAlAs strain-balanced QWs exhibit low threshold current density, high T0 (78.0 #x000B0;C) and high resonance frequency (24 GHz) indicating that a large number of shallow barrier QWs are attractive for un-cooled high-speed direct-modulation applications.
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| 8. |
- Isaksson, M., et al.
(författare)
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10 Gb/s direct modulation of 40 nm tunable modulated-grating Y-branch laser
- 2005
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Ingår i: Optical Fiber Communication Conference, 2005. Technical Digest. OFC/NFOEC. - 1557527830 - 9781557527837 ; , s. 117-119
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Konferensbidrag (refereegranskat)abstract
- High speed properties of a directly modulated widely tunable MG-Y laser have been evaluated. Small signal response and 10 Gb/s NRZ modulation were performed within the 40 nm tuning range.
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| 9. |
- Kjebon, Olle, 1960-, et al.
(författare)
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Modulation response measurements and evaluation of MQW InGaAsP lasers of various designs
- 1996
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Ingår i: Proc. SPIE, Vol. 2684. - : SPIE. ; , s. 138-152
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Resultsfrom modulation measurements of 40 high-speed multi quantum well (MQW)lasers ((lambda) equals 1.55 micrometer) of various designs are presented.By fitting the careful calibrated measurements, both magnitude and phase,to an analytical transfer function we were able to determineif a certain laser was limited by thermal effects, parasitic-likeeffects, or nonlinear gain effects. We found that most ofthe devices in the study were limited by thermal effectsand/or contact parasitics. The parasitics were found to be determinedby the width of the high-doped contact layer and claddinglayers below the metallic contact. It was also found thata high doping of the separate confinement heterostructure (SCH) layersdecreases the damping of the relaxation peak since it facilitatesthe carrier transport. Improved contact design and high doped SCH-layersresulted in modulation bandwidths of around 24 GHz.
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| 10. |
- Kjebon, Olle, 1960-, et al.
(författare)
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Transmission at 20 Gb/s with directly modulated DBR lasers over 30 km standard fiber
- 2002
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Ingår i: Optical Communication, 2002. ECOC 2002. 28th European Conference on. ; , s. 1-2
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Konferensbidrag (refereegranskat)abstract
- Transmission of 20 Gb/s NRZ over 30 km of standard fiber was accomplished with directly modulated DBR lasers at 1.55 mum. Experiments were performed without dispersion compensation and optical amplification and a negative penalty was observed
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| 11. |
- Kjebon, Olle, 1960-, et al.
(författare)
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Two-section InGaAsP DBR-lasers at 1.55 mu;m wavelength with 31 GHz direct modulation bandwidth
- 1997
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Ingår i: Indium Phosphide and Related Materials, 1997., International Conference on. ; , s. 665-668
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Konferensbidrag (refereegranskat)abstract
- The small signal modulation response of two-section InGaAsP DBR-lasers at 1.55 mu;m wavelength was investigated. The response was fitted to a general transfer function and it was found that for almost all lasers the response could be described by a three pole model consisting of the laser response from the standard rate equations and an additional first order low pass roll-off. The lasers exhibited reduced damping and increased resonance frequency due to what we believe is detuned loading. This led to a maximum bandwidth of 30 GHz for lasers described by the three pole model. Some lasers exhibited an additional effect which we believe is cavity resonant enhancement of one of the modulation side-bands. This effect increased the maximum -3dB bandwidth to 31 GHz but could not be described by a three pole model
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| 12. |
- Lee, H. L. T., et al.
(författare)
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Bandwidth enhancement and chirp reduction in DBR lasers by strong optical injection
- 2000
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Ingår i: Lasers and Electro-Optics, 2000. (CLEO 2000). Conference on. ; , s. 99-100
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Konferensbidrag (refereegranskat)abstract
- We have observed modulation bandwidth enhancement to 28 GHz and evidence of reduced chirp, beyond the optimally tuned free running case, in strongly injection-locked DBR lasers. Bandwidth enhancement occurs because the total modal photon density depends on the phase between the master and slave fields, which varies during modulation due to the dependence of index on carrier density. This results in an increased coupling between the carriers and photons, giving an effectively higher differential gain. This effect appears to be stronger than the similar amplitude-phase coupling that occurs with detuned loading. Chirp reduction occurs only for very strong injection, which can be explained by the fact that chirp reduction can only be achieved for modulation frequencies less than the locking range, which increases with injected power. For higher frequencies, the chirp reduction due to detuned loading dominates
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| 13. |
- Lee, H. L. T., et al.
(författare)
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Enhanced direct modulation efficiency by FM to IM conversion
- 2000
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Ingår i: Microwave Photonics, 2000. MWP 2000. International Topical Meeting on. ; , s. 105-108
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Konferensbidrag (refereegranskat)abstract
- Enhanced modulation efficiency of a directly modulated, high speed DBR laser of up to 400% has been demonstrated using FM to IM conversion in optical fiber. The link noise figure is improved by 8 dB and the dynamic range by 3 dB at 10 GHz
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| 14. |
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| 15. |
- Lindgren, S., et al.
(författare)
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Laser flip-chip mounting for passive alignment and high-frequency modulation
- 1996
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Ingår i: Optical Communication, 1996. ECOC ’96. 22nd European Conference on. ; , s. 103-106
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Konferensbidrag (refereegranskat)abstract
- We have developed a silicon motherboard for flip-chip mounting of lasers in a way that is compatible with high-frequency modulation (24 GHz) and which allows passive alignment of the lasers to single-mode fibres.
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| 16. |
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| 17. |
- Liu, C. P., et al.
(författare)
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High-Speed 1.56-μm Multiple Quantum Well Asymmetric Fabry-Perot Modulator/Detector (AFPMD) for Radio-Over-Fibre Applications
- 2005
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Ingår i: Microwave Photonics, 2005. MWP 2005. International Topical Meeting on. - : IEEE. ; , s. 137-140
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Konferensbidrag (refereegranskat)abstract
- We have designed and fabricated air-bridged optical modulator/detectors with modulation bandwidth exceeding 15GHz, the highest yet reported for InGaAsP/InGaAsP MQW AFPMDs. Wavelength dependence of the modulated output power at microwave frequencies is reported for the first time and the wide optical bandwidths ( gt; 17nm) so measured suggest that the AFPMD can be used with low-cost uncooled CWDM lasers in radio-over-fibre applications.
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| 18. |
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| 19. |
- Pfrommer, H., et al.
(författare)
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Experimental Demonstration of Full-Duplex DOCSIS Signal Transmissions over a Wireline/Wireless-Fibre Access Network
- 2006
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Ingår i: 2006 International Topical Meeting on Microwaves Photonics. ; , s. 89-92
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Konferensbidrag (refereegranskat)abstract
- A fibre-radio access network architecture for simultaneous wireline and wireless transmissions of data over cable service interface specification (DOCSIS) signals is presented. An all-optical harmonic up-conversion technique using a dual-drive Mach-Zehnder modulator (DD-MZM) is employed at the central station while an InGaAsP/InGaAsP multiple quantum well (MQW) asymmetric Fabry-Perot modulator/detector (AFPM) functions as a single optical/electrical transducer performing optical intensity modulation and photodetection simultaneously at the base station. Full-duplex operation is demonstrated for both access types in an indoor laboratory environment as well as in a small-scale outdoor field trial
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| 20. |
- Schatz, Richard, 1963-, et al.
(författare)
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Design and evaluation of high speed DBR lasers for analog and digital transmission
- 2003
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Ingår i: Laser and Fiber-Optical Networks Modeling, 2003. Proceedings of LFNM 2003. 5th International Workshop on. ; , s. 32-37
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Konferensbidrag (refereegranskat)abstract
- The directly modulated laser is a simple and reliable source for high speed optical transmission of information. It is especially useful in medium to short distance digital links (e.g. metropolitan and local area networks) where the excess pulse dispersion due to laser chirp is not a critical issue. The linear current to light conversion makes it also interesting for transmission of analogue signals over fiber (CATV and microwave links). In both cases a high bandwidth is needed in order to maximize the transmission capacity and retain good distortion characteristics. For single section DFB lasers with low electrical parasitics, the bandwidth is mainly determined by the differential gain of the active material. There has been little progress in improving this material parameter lately beyond what was achieved with the introduction of strained quantum wells. A theoretical and experimental investigation of another approach to further improve the modulation bandwidth, namely by utilizing the dispersive feedback from a detuned Bragg grating in a DBR laser.
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| 21. |
- Schatz, Richard, 1963-, et al.
(författare)
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Enhanced modulation bandwidth and self-pulsations in detuned loaded InGaAsP DBR-lasers
- 1996
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Ingår i: Semiconductor Laser Conference, 1996., 15th IEEE International. ; , s. 93-94
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Konferensbidrag (refereegranskat)abstract
- A strong undamping of the relaxation peak leading to self-pulsations and a record high modulation bandwidth (26 GHz) were observed in 1.55 mu;m InGaAsP DBR QW lasers. These results are attributed to the mechanism of detuned loading
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| 22. |
- Schatz, Richard, 1963-, et al.
(författare)
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High speed direct modulation of semiconductor lasers
- 2004
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Ingår i: 30th European Conference on Optical Communications, Proc. of ECOC2004. ; , s. 444-447
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Konferensbidrag (refereegranskat)abstract
- The key parameters for direct modulation of semiconductor lasers are identified. The possibility to further extend the bandwidth is discussed and an overview of our work on detuned loaded DBR lasers is given
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