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Lateral current injection (LCI) multiple quantum-well 1.55 mu m laser with improved gain uniformity across the active region
KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
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.

Place, publisher, year, edition, pages
2004. Vol. 36, no 9, 827-846 p.
Keyword [en]
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: urn:nbn:se:kth:diva-24235DOI: 10.1023/B:OQEL.0000040062.76050.bfISI: 000223644100005Scopus ID: 2-s2.0-4444366097OAI: oai:DiVA.org:kth-24235DiVA: diva2:345848
Note
QC 20100827Available from: 2010-08-27 Created: 2010-08-27 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Photonic devices with MQW active material and waveguide gratings: modelling and characterisation
Open this publication in new window or tab >>Photonic devices with MQW active material and waveguide gratings: modelling and characterisation
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
Method of Lines, Grating, ARROW Waveguide, Semiconductor laser, quantum well
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-433 (URN)91-7178-132-3 (ISBN)
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

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