NANOLASE: Nanofabrication of strongly gain coupled lasers for high speed communication and sensor applications

• Research unit: EU RFP
• Project number: 95.0868

Key words (English)

Semiconductor Lasers; DFB lasers; gain coupling; single mode operation; sensord

Alternative project number (English)

EU project number: EP 22.497

Research programs (English)

EU-programme: 4. Frame Research Programme - 1.3 Telematic systems

Short description (English)

See abstract

Further information (English)

Full name of research-institution/enterprise:
EPF Lausanne
Département de Physique
Institut de Micro- et Optoélectronique

Partners and International Organizations (English)

Alcatel-Alsthom Research, Marcoussis, CENT, Laboratoire de Bagneux, Kungliga Techniska Högskolan, Kista. Paul Drude Institut, Berlin. Thomson CSF,Orsay, University of Stuttgart, Institute of Solid State Physics, Chernogolovoka, Lebedev Physical Institute, Moscow

Abstract (English)

We have compared two gain coupled DFB laser structures. Type 1 laser structure consists in the overgrowth of the active region directly on the grating to achieve gain medium modulation, type 2 structure in the etching of the gratings above the gain medium, gain-coupling being obtained from the vertical emission. The active region been grown before realization of the gratings, it is not subject to possible interface contamination. Both laser structures operate in a single DFB mode at room temperature. Quasi-CW and CW emission are obtained for structure 1 and 2 respectively. Structure 1 only lases quasi-CW due to high contact resistance. The Jth is very difficult to reproduce for all type 1 structures, either with 1 or 3 QWs. It varies up to several kAIcm2. This large spread is attributed to the inhomogeneity and the non-reproducibility of the interface cleaning before the second growth. Structure 2 yields threshold currents, Ith as low as %mA for 3um wide mesas. Broad area lasers show quite reproducible Jth = 300A/cm2 for a number of growth batches.
Both structures show a high monomode yield > 75% with a side mode suppression ratio (SMSR) larger than 40dB irrespective of variations. An external quantum efficiency, ntotal = 40% is measured for both structures with monomode output power up to 20mW. This includes the emission of both facets and the vertical radiation. The external quantum efficiencies from the right and left facets: nright and nleft, and from the vertical emission: nsurf, depend on the laser length and on the facet phases relative to the grating.

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 95.0868