CST Global presents detuned DFB lasers for increased modulation efficiency in fiber-optic transmission

III-V optoelectronic foundry Compound Semiconductor Technologies Global Ltd (CST Global) of Hamilton International Technology Park, Blantyre, near Glasgow, Scotland, UK says that, at the III International Conference on Applications in Optics and Photonics (AOP 2017) in Faro, Portugal (8-12 May), research engineer Horacio Cantu presented his recently published white paper ‘Performance characteristics of 1550nm and 1310nm detuned, ridge waveguide, distributed feedback, laser diodes’ (AO100-194), co-authored by director of engineering Andrew McKee.

The paper acts as an interim summary by CST Global for the project iBROW (Innovative ultra-Broadband Ubiquitous Wireless Communications Through Tera-hertz Transceivers). Led by the University of Glasgow, iBROW is a funded, research project looking at the development of new technology platforms for ultra-broadband communication networks of multiple Gigabits/second – massively out-performing current platforms.

“We can modulate light with radio-data, for transmission over fiber-optic networks, without analog-to-digital conversion,” says Cantu. “The available bandwidth is huge; there is almost no latency; and the data can remain in its original format, for transmission via passive networks,” he adds.

The white paper is concerned with the performance of in-plane, ridge-waveguide distributed feedback (DFB) laser diodes for data transmission, centred on 1550nm and 1310nm wavelengths. “We successfully showed that ‘detuning’ DFB lasers from their peak optical gain increases modulation efficiency; a bias power to frequency characteristic proportional to data carrying capacity or bandwidth,” says Cantu. “We also showed that, as the temperature increases from 25°C to 85°C, modulation efficiency can also be increased,” he adds.

Both carrier wavelengths enable an ultra-broadband solution. “We found 1310nm lasers had greater modulation efficiency than 1550nm lasers. However, because 1550nm has a much larger transmission range, more research is required to establish if it is the best, practical, ultra-broadband solution in the long-term,” Cantu notes.

“We are a long way from a commercial, ultra-broadband solution that is low cost, energy efficient, compact, operates at room temperature, and integrates consumer portable devices and fiber-optic networks.” However, the white paper concludes that detuning DFB laser transmitters increases bandwidth capacity in optical fiber networks.