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Photonic devices with MQW active material and waveguide gratings: modelling and characterisation
KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The research work presented in this thesis deals with modelling, design and characterisation of passive and active optical waveguide devices. The rst part of the thesis is related to algorithm development and numerical modelling of planar optical waveguides and gratings using the Method of Lines (MoL). The basic three-point central-di erence approximation of the δ2=δx2 operator used in the Helmholtz equation is extended to a new ve-point and seven-point approximation with appropriate interface conditions for the TE and TM elds. Di erent structures such as a high-contrast waveguide and a TM surface plasmon mode waveguide are simulated, and improved numerical accuracy for calculating the optical mode and propagation constant is demonstrated. A new fast and stable non-paraxial bi-directional beam propagation method, called Cascading and Doubling algorithm, is derived to model deep gratings with many periods. This algorithm is applied to model a quasi-guided multi-layer anti-resonant reecting optical waveguide (ARROW) grating polarizing structure.

In the second part of the thesis, our focus is on active optical devices such as vertical-cavity and edge-emitting lasers. With a view to improve the bandwidth of directly modulated laser, an InGaAsP quantum well with InGaAlAs barrier is studied due to its favorable band o set for hole injection as well as for electron con nement. Quantum wells with di erent barrier bandgap are grown and direct carrier transport measurements are done using time and wavelength resolved photoluminescence upconversion. Semi-insulating regrown Fabry-Perot lasers are manufactured and experimentally evaluated for light-current, optical gain, chirp and small-signal performance. It is shown that the lasers having MQW with shallow bandgap InGaAlAs barrier have improved carrier transport properties, better T0, higher di erential gain and lower chirp. For lateral current injection laser scheme, it is shown that a narrow mesa is important for gain uniformity across the active region. High speed directly modulated DBR lasers are evaluated for analog performance and a record high spurious free dynamic range of 103 dB Hz2=3 for frequencies in the range of 1-19 GHz is demonstrated. Large signal transmission experiment is performed at 40 Gb/s and error free transmission for back-to-back and through 1 km standard single mode ber is achieved.

Place, publisher, year, edition, pages
Stockholm: KTH , 2005. , xvi, 82 p.
Series
Trita-MVT, ISSN 0348-4467 ; 2005:3
Keyword [en]
Method of Lines, Grating, ARROW Waveguide, Semiconductor laser, quantum well
National Category
Telecommunications
Identifiers
URN: urn:nbn:se:kth:diva-433ISBN: 91-7178-132-3 (print)OAI: oai:DiVA.org:kth-433DiVA: diva2:11828
Public defence
2005-10-07, Sal C1, KTH-Electrum, 10:00
Opponent
Supervisors
Note
QC 20100827Available from: 2005-09-27 Created: 2005-09-27 Last updated: 2010-08-27Bibliographically approved
List of papers
1. A new higher order finite-difference approximation scheme for the method of lines
Open this publication in new window or tab >>A new higher order finite-difference approximation scheme for the method of lines
2001 (English)In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 19, no 3, 398-404 p.Article in journal (Refereed) Published
Abstract [en]

A new 5-point and a 7-point nonuniform mesh finite-difference scheme is introduced to approximate the second-derivative operator. The scheme is applied using the method of lines. The necessary interface conditions for the TE and TM fields at an index discontinuity are appropriately included in the derivation. This scheme can model lossy dielectrics as well as metallic layers in a unified way. Numerical results are given for the fundamental TE and TM modes of a high-contrast waveguide and for a metal/dielectric single interface TM surface-plasmon mode showing excellent convergence behavior to the analytical results.

Keyword
Finite-difference methods; Higher order approximations; Method of lines (MoL); Optical waveguides; Surface plasmon mode; Approximation theory; Dielectric materials; Finite difference method; Mathematical operators; Optimization; Method of lines (MoL); Partial differential equations
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-24230 (URN)10.1109/50.918894 (DOI)000168385600014 ()
Note
QC 20100827Available from: 2010-08-27 Created: 2010-08-27 Last updated: 2010-08-27Bibliographically approved
2. Analysis of deep waveguide gratings: an efficient cascading and doubling algorithm in the method of lines framework
Open this publication in new window or tab >>Analysis of deep waveguide gratings: an efficient cascading and doubling algorithm in the method of lines framework
2002 (English)In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 20, no 7, 1204-1209 p.Article in journal (Refereed) Published
Abstract [en]

In this work, a computationally fast, numerically stable, and memory-efficient cascading and doubling algorithm is proposed within the method of lines framework to model long planar waveguide gratings having thousands of periods in the propagation direction. This algorithm can model 2(n) grating periods in n calculational steps and needs N-2 matrices for N sample points in the problem space. It can model periodic, quasi-periodic, symmetric, and asymmetric, gratings efficiently. Different deep waveguide gratings are modeled using this scheme and results for the fundamental TE mode spectral reflectivity are compared with published results showing excellent agreement.

Keyword
Beam-propagation methods; Finite-difference methods; Method of lines (MoL); Optical waveguides; Waveguide discontinuities; Waveguide gratings; Algorithms; Computational methods; Diffraction gratings; Finite difference method; Light propagation; Mathematical models; Matrix algebra; Cascading algorithms; Deep waveguide gratings; Doubling algorithms; Method of lines; Optical waveguides
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-24231 (URN)10.1109/JLT.2002.800350 (DOI)000177576700017 ()
Note
QC 20100827Available from: 2010-08-27 Created: 2010-08-27 Last updated: 2010-08-27Bibliographically approved
3. Analysis of antiresonant reflecting optical waveguide gratings by use of the Method of Lines
Open this publication in new window or tab >>Analysis of antiresonant reflecting optical waveguide gratings by use of the Method of Lines
2003 (English)In: Applied Optics, ISSN 0003-6935, E-ISSN 1539-4522, Vol. 42, no 18, 3488-3494 p.Article in journal (Refereed) Published
Abstract [en]

The modal spectral response of an antiresonant reflecting optical waveguide (ARROW) with periodic corrugations or grating is calculated for both shallow and deep gratings with the Method of Lines. The effect of the ARROW layer thickness and the grating depth on the spectral response is studied. It is found that when the ARROW-layer thickness is close to resonance, the ripples in the reflection spectra become smooth and the peak reflectivity drops. This is attributed to the large increase in the leakage loss of the ARROW waveguide near resonance. The ARROW grating is characterized by modal reflectivity spectra, which exhibit a strong polarization discrimination property, in favor of the TE polarization.

Keyword
Spectral response; Diffraction gratings; Light polarization; Optical fibers; Optical waveguides
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-24233 (URN)10.1364/AO.42.003488 (DOI)000183661700005 ()
Note
QC 20100827Available from: 2010-08-27 Created: 2010-08-27 Last updated: 2010-08-27Bibliographically approved
4. Influence of electrical parasitics and drive impedance on the laser modulation response
Open this publication in new window or tab >>Influence of electrical parasitics and drive impedance on the laser modulation response
2004 (English)In: IEEE Photonics Technology Letters, ISSN 1041-1135, E-ISSN 1941-0174, Vol. 16, no 1, 21-23 p.Article in journal (Refereed) Published
Abstract [en]

In this letter, we analyze the effects of electrical parasitics and drive impedance on the laser modulation response. It is found that for lasers with small active-region volume, e.g., vertical-cavity surface-emitting lasers, the finite drive impedance and/or the laser parasitic capacitance can significantly enhance the damping of the laser resonance peak at low bias. This is due to the voltage fluctuations across the laser diode active layer during modulation. It is also shown that the real pole of the small-signal response transfer function corresponding to the laser parasitic cutoff frequency is not fixed but decreases with the increased bias level.

Keyword
laser dynamics, laser modeling, rate equations, quantum-well lasers, equivalent-circuit
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-23076 (URN)10.1109/lpt.2003.819404 (DOI)000187885800007 ()2-s2.0-0346707366 (Scopus ID)
Note
QC 20100827Available from: 2010-08-10 Created: 2010-08-10 Last updated: 2010-08-27Bibliographically approved
5. Design optimization of InGaAsP-InGaAlAs 1.55 mu m strain-compensated MQW lasers for direct modulation applications
Open this publication in new window or tab >>Design optimization of InGaAsP-InGaAlAs 1.55 mu m strain-compensated MQW lasers for direct modulation applications
2004 (English)In: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 19, no 5, 615-625 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, a simulation study of InGaAsP(well)/InGaAlAs(barrier) 1.55 mum strain-compensated multi-quantum well (MQW) lasers is presented. Due to a large conduction band discontinuity in this material system, a higher material gain and differential gain can be obtained from such a quantum well (QW) as compared to a traditional InGaAsP/InGaAsP quantum well. The deeper electron well should also improve elevated temperature operating characteristics and reduce the electron spillover from QWs. For MQWs, a uniform vertical distribution of holes is achieved due to a reduced effective hole confinement energy by optimizing the bandgap and the strain in the barriers. A large number of quantum wells can be uniformly pumped, reducing the carrier density in each individual well. A uniform and low carrier density in all the wells help reduce the total Auger recombination current. High p-doping in the active region is shown to enhance the carrier and gain non-uniformity in the MQWs. A simulated high modulation bandwidth has been demonstrated, promising directly modulated lasers as a low-cost source for short to medium distance (1-10 km) high speed optical links.

Keyword
quantum-well lasers, differential gain, carrier transport, band offsets, layer, wavelength, bandwidth, diodes, inp, performance
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-23462 (URN)10.1088/0268-1242/19/5/010 (DOI)000221732000014 ()2-s2.0-2542481881 (Scopus ID)
Note

QC 20100827

Available from: 2010-08-10 Created: 2010-08-10 Last updated: 2014-12-09Bibliographically approved
6. Lateral current injection (LCI) multiple quantum-well 1.55 mu m laser with improved gain uniformity across the active region
Open this publication in new window or tab >>Lateral current injection (LCI) multiple quantum-well 1.55 mu m laser with improved gain uniformity across the active region
2004 (English)In: Optical and quantum electronics, ISSN 0306-8919, E-ISSN 1572-817X, Vol. 36, no 9, 827-846 p.Article in journal (Refereed) Published
Abstract [en]

A simulation study of lateral current injection 1.55 mum laser with strain-compensated multiple quantum-well (MQW) active region (InGaAsP well, InGaAlAs barrier) is presented using self-consistent 2D numerical simulations. The effects of different mesa width and p-doping in the QWs on the carrier and gain uniformity across the active region are explored. A high p-doping in the quantum wells is found to increases the carrier and gain non-uniformity across the active region. The QW region close to the n-contact side does not provide much gain at high optical powers. An asymmetric optical waveguide design is proposed to help reduce the gain non-uniformity across the active region. By shifting the optical modal peak toward the p-side, the modal overlap between the gain region and the optical mode is improved and a more even carrier and gain distribution is obtained. However, due to reduced bandgap of the quaternary InGaAsP p-cladding, an enhanced electron leakage out of the QWs into the p-cladding degrades the laser efficiency and increases the threshold current. Transient time - domain simulations are also performed to determine the small-signal modulation response of the laser promising a simulated high modulation bandwidth suitable for direct-modulation applications.

Keyword
Directly modulated lasers; Lateral current injection; Multiple quantum well; Bandwidth; Cladding (coating); Computer simulation; Heterojunctions; Laser beam effects; Particle beam injection; Phase modulation; Quantum well lasers
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-24235 (URN)10.1023/B:OQEL.0000040062.76050.bf (DOI)000223644100005 ()2-s2.0-4444366097 (Scopus ID)
Note
QC 20100827Available from: 2010-08-27 Created: 2010-08-27 Last updated: 2010-08-27Bibliographically approved
7. The effect of barrier composition on the vertical carrier transport and lasing properties of 1.55-mu m multiple quantum-well structures
Open this publication in new window or tab >>The effect of barrier composition on the vertical carrier transport and lasing properties of 1.55-mu m multiple quantum-well structures
Show others...
2006 (English)In: IEEE Journal of Quantum Electronics, ISSN 0018-9197, E-ISSN 1558-1713, Vol. 42, no 7, 713-714 p.Article in journal (Refereed) Published
Abstract [en]

In this paper, the effect of barrier bandgap and composition on the optical performance of 1.55-mu m InGaAsP/In-GaAsP and InGaAsP/InGaAlAs multiple quantum-well structures and Fabry-Perot lasers is evaluated experimentally. Direct vertical carrier transport measurements were performed through strain-compensated multiple quantum-well (MQW) test structures using femto-second laser pulse excitation and time-resolved photoluminescence up-conversion method. MQW test structures were grown with different barrier composition (InGaAsP and InGaAlAs) and barrier bandgap (varied from lambda(g) = 1440 to 1260 nm) having different conduction band Delta E-c and valence band discontinuity Delta E-v, while keeping the same InGaAsP well composition for all the structures. The ambipolar carrier transport was found to be faster in the structures with lower valence band discontinuity Delta E-v. Regrown semi-insulating buried heterostructure Fabry-Perot (SIBH-FP) lasers were fabricated from similar QWs and their static light-current-voltage characteristics (including optical gain and chirp spectra below threshold) and thermal characteristics were measured. Lasers with InGaAlAs barrier showed improved high-temperature operation, higher optical gain, higher differential gain, and lower chirp, making them suitable candidates for high-bandwidth directly modulated uncooled laser applications.

Keyword
Carrier transport; Fabry-Perot laser; InGaAIAs; InGaAsP; Quantum well (QW); Time-resolved photo luminescence
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-24236 (URN)10.1109/JQE.2006.876710 (DOI)000239404700013 ()2-s2.0-51849096527 (Scopus ID)
Note

QC 20100827

Available from: 2010-08-27 Created: 2010-08-27 Last updated: 2017-06-08Bibliographically approved
8. 40 Gb/s transmission experiment using directly modulated 1.55 mu m DBR lasers
Open this publication in new window or tab >>40 Gb/s transmission experiment using directly modulated 1.55 mu m DBR lasers
2003 (English)In: Conference Proceedings - International Conference on Indium Phosphide and Related Materials, 2003, 495-498 p.Conference paper, Published paper (Refereed)
Abstract [en]

Directly modulated two section 1.55 mum InGaAsP DBR lasers were used for 40 Gb/s error free operation back-to-back and through 1 km of standard single mode fiber.

Series
Conference Proceedings - Indium Phosphide And Related Materials, ISSN 1092-8669
Keyword
Bit error rate, Fiber Bragg gratings, Fiber lasers, Light modulation, Semiconducting indium gallium arsenide, Semiconducting indium phosphide, Single mode fibers, Distributed Bragg reflector lasers, Transmission back-to-back, Semiconductor lasers
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-24237 (URN)000183253000127 ()0-7803-7704-4 (ISBN)
Conference
2003 International Conference Indium Phosphide and Related Materials; Santa Barbara, CA; 12-16 May 2003
Note
QC 20100827 NR 20140804Available from: 2010-08-27 Created: 2010-08-27 Last updated: 2012-02-15Bibliographically approved
9. Experimental evaluation of detuned loading effects on distortion in edge emitting DBR lasers
Open this publication in new window or tab >>Experimental evaluation of detuned loading effects on distortion in edge emitting DBR lasers
2002 (English)In: International Topical Meeting on Microwave Photonics, 2002, 2002, 125-128 p.Conference paper, Published paper (Refereed)
Abstract [en]

Detuned loading in directly modulated DBR lasers has been evaluated. IMD3 was measured, yielding a spurious free dynamic range for frequencies 1-19 GHz.

National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-24239 (URN)7690875 (Local ID)4-88552-187-4 (ISBN)7690875 (Archive number)7690875 (OAI)
Conference
International Topical Meeting on Microwave Photonics, 5-8 Nov. 2002
Note
QC 20100827Available from: 2010-08-27 Created: 2010-08-27 Last updated: 2010-08-27Bibliographically approved

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