InP-based Long Wavelength Sources for Solid State Lasers Pumping
Abstract
For GaAs-based diode lasers (DL) operating in the 790 - 980 nm range, major power limitations are associated with catastrophic optical degradation (COD) of mirror facets and, measurably, other reliability issues. Reliability concerns do not limit the performance of InP-based diode lasers to such a large extent. The maximum power for these devices is determined by the "initial", near-threshold differential efficiency eta(sub d-max) and the rate of eta(sub d-max) reduction with increasing pump current (P-I characteristic rollover). Rollover effect is negligible in GaAs-based lasers since the T(sub 0) and T(sub 1) parameters characterizing the temperature dependencies of the threshold and eta(sub d) are much higher than those for InP-based emitters. Rollover power limitation can be reduced by using devices with long cavity length, provided the internal optical losses (alpha sub int) are low and eta(sub d-max) does not decrease considerably with increasing cavity length. Therefore, alpha(sub int) reduction is a key to achieving high-power InP-based diode lasers. The absorption loss analysis in InP lasers [1] shows that the absorption by free holes in the p-InP cladding layer and in Quantum Wells (QW) are the major loss mechanisms. So far, three approaches have been used to reduce absorption losses: (i) the thickness of undoped waveguide was increased up to 1300 nm to prevent the lasing mode penetration into the p-doped cladding layer (Broad Waveguide design) [2]; (ii) stepped acceptor doping profile in p-InP cladding was used in structures with narrow waveguide [3,4]; (iii) the number of QW was reduced from 3 to 2 in the last version of the narrow waveguide structures [4]. In this paper we present the parameters of recently developed InGaAsP/InP single element lasers and diode laser arrays emitting at approx 1850 nm and approx. 1450 nm. For fabrication of 1850-nm emitters the structure with total waveguide thickness W=1000 nm (Fig. 1) was used.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2004
- Accession Number
- ADA512037
Entities
People
- D. Garbuzov
- M. Dubinskii