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Sensors and Devices

Microwave Photonics generation using low-cost vertical cavity surface-emitting lasers

Research Background

Microwave photonics has been defined as the study of the interaction between microwave and optical waves. It is particularly suited to radio-over-fibre technologies and in particular, holds great promise for future 5G technology.


Microwave photonics has several key advantages over conventional electrical-transmission systems, such as coaxial cables, these include, reduced physical size, weight and cost; lower attenuation over the entire microwave and millimetre-wave modulation frequency range; greater immunity to electromagnetic interference; low dispersion and high data-transfer capacity.

The Challenge

Conventional method to generate microwaves signals by using electronic circuits has begun to struggle to meet the increasing demand for higher frequency microwave generation. An alternative approach, which uses photonics to assist microwaves generation, processing, and distribution, is increasingly drawing interest. The existing methods used to generate microwave signals using photonics include direct modulation, optical phase lock loop, external modulation, mode-locked semiconductor lasers, and electro-optic oscillator. However, all of these techniques require either a lower frequency external microwave source or a microwave filter, both of which are expensive.


Nonlinear dynamics of optically injected VCSELs can be used to generate microwave signals, which no external microwave source or a microwave filter is required. Also VCSEL offers the other salient advantages: low threshold current, low power consumption and high reliability.

Current Developments

In this project, Dr Hong is exploring the generation of microwave photonics using a low-cost approach. She investigates the generation of a broadband, tunable high frequency microwave source based on the period one dynamics of a low-cost VCSELs subject to optical injection. This approach has the advantage of not requiring any high-frequency electronic components.


The nonlinear dynamics of optically injected semiconductor lasers have been used to generate microwave signals. Most of the research has used a DFB laser; however, the price of a DFB laser is more than 10 times higher than that of a VCSEL. The use of VCSEL therefore offers a means of obtaining low-cost generation of microwave signals.

The exploitation of VCSEL properties within microwaves generation provides a technology to enable low cost, low power consumption and low complexity.
Dr Yanhua Hong

Impact

The exploitation of VCSEL properties within microwaves generation provides a direct interface with industrial requirements in communications for technology to enable low cost, low power consumption and low complexity. Such low power consumption and low complexity have been identified as a potent means whereby photonics can contribute to the reduction of the carbon footprint of communications technologies.


Through this collaboration with IQE, the project will explore a new application for VCSELs. Therefore, this R&D project provides an exciting commercial opportunity, possibly leading to commercialisation through licensing or a spin out.

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Case Study Contacts

Dr Yanhua Hong
Advanced Sensors and Devices
July 2016