A key product of nanoplus are complex coupled distributed feedback laser diodes. nanoplus provides these monomode semiconductor lasers at any wavelength between 760 nm and 14000 nm. nanoplus DFB lasers have the following advantages:

• stable longitudinal and transversal single mode emission
• precise selection of target wavelength
• narrow laser line width
• mode-hop-free wavelength tunability
• fast wavelength tuning
• typically > 5 mW output power
• small size
• easy usability
• high efficiency
• long-term stability

Unique concept of nanoplus DFB lasers

Semiconductor lasers in general are known as compact and reliable light sources with high wall-plug efficiency. While Fabry Perot laser diodes typically operate only transversal single mode, both Distributed Feedback and Distributed Bragg Reflector laser diodes contain an integrated grating structure for longitudinal mode selection, resulting in narrow band emission.

DFB devices are ideally suited to provide longitudinal and transversal single mode emission at a precise wavelength with an extremely narrow line width. They guarantee high output power and mode-hop-free tunability compared to a DBR device and are ideally suited to meet the high requirements of TDLAS gas sensing applications.

Conventionally the grating structure in a DFB or DBR device is defined by an etch process during a growth interruption step shortly after the growth of the active region of the laser structure. The pre-patterned structure is then inserted into the epitaxy reactor again and overgrown. As the growth on a pre-patterned surface is much more demanding as the usual growth on a planar substrate (different orientations requiring different overgrowth conditions, defects introduced in the overgrowths by residual impurities due to the pre-patterning process) the performance of single mode lasers made by this technique in most systems including e. g. the GaAs and the GaSb substrate system is significantly degraded by this type of processing.

In contrast, the unique and patented nanoplus DFB concept (shown schematically in Figure 1) is based on an overgrowth-free approach avoiding the need to develop high quality orientation independent growth and avoiding per se the insertion of patterning induced defects near the active layer.

nanoplus puts great value on R&D to provide our customers with cutting-edge products. Our technological advances resulted in a number of patents, such as patent numbers US 6.671.306, US 6.846.689 and EP0984535. In addition we have licence agreements with the US Department of the Navy, Naval Research Laboratory for the production of Interband Cascade Lasers as well as with Alcatel-Lucent USA Inc. for the production of Quantum Cascade Lasers.

In nanoplus DFB lasers complex coupling is obtained by combining a ridge waveguide structure with metal gratings on top of the waveguide layer on both sides of the laser ridge. DFB lasers realized by this technique show

• high performance (SMSR > 40 dB, feedback, tolerance)
• independence of material system (GaAs, InP and GaSb)
• low capitance BCB planarisation for high Gbit / s operation

compared to conventional DFB laser diodes. Thresholds and efficiencies correspond to those of Fabry Perot lasers realized from the same layer structures, while mode-hop free operation combined with a high SMSR is guaranteed in the entire specified temperature and power range of operation.

Most importantly, the nanoplus DFB concept is largely independent on the underlying laser structure and can easily be adopted to a variety of independent epitaxial designs. Based on this approach, nanoplus manufactures and sells DFB laser diodes in the entire wavelength range from 760 nm up to 3000 nm. In addition, nanoplus offers DFB interband cascade lasers from 3000 nm to 6000 nm and DFB quantum cascade lasers at wavelengths between 6000 nm and 14000 nm.

Types of semiconductor lasers

More specifically, from the general physics point-of-view, nanoplus offers three different types of semiconductor lasers based on slightly different lasing principles:

I. Bipolar Laser Diodes from 760 nm to 3000 nm

II. Interband Cascade Lasers from 3000 nm to 6000 nm

III. Quantum Cascade Lasers from 6000 nm to 14000 nm