RF and Microwave Photonics in Biomedical Applications

Abstract

In the last 20 years the field of microwave photonics has evolved due to unique features of analogue fibre-optic systems and its applications in radio over fibre for telecommunications [1] and optically controlled phased array antennas [2] for military applications, as has been discussed in earlier chapters of this book. Recently, microwave photonics techniques have also been extended to biomedical systems and this chapter presents two distinctive biomedical imaging applications that employ these techniques. (Optics already lends its application to laser Doppler anemometry, optical biopsy and optical molecular imaging, and phase microscopy.) The first application to be discussed is the design and implementation of optical hydrophone for calibration of ultrasound transducers for frequencies up to 100 MHz, which has found applications in sub-millimeter wave imaging and therapeutic applications. The second is the use of broadband modulated near infrared (NIR) light waves for quantifying blood flow and cellular functionality using spectroscopy, which is to be applied to coagulation monitoring and functional imaging with sub-centimetre spatial resolution using photon density waves. Both techniques are first discussed in terms of the fundamental physical interaction of lightwaves with biological tissues and the technical advantages that RF and microwave photonics could bring to conventional imaging modalities. Introduction to Optical HydrophoneOnly a decade ago, the highest ultrasound imaging frequency was of the order of 7 MHz. Today, modern diagnostic machines, particularly those designed for applications such as dermatology, ophthalmology and microsurgery, operate at centre frequencies close to 15 or 20 MHz [3].

Modeling and tissue parameter extraction challenges for free space broadband fNIR brain imaging systems

“…It is proposed that broadband frequency modulation would give a better and more accurate assessment for optical parameter extraction. Studies show 22,23 that broadband modulation (DC-1GHz) would give a high accuracy when both malignant and benign tumor is present. These studies were based on fiber optical system, and would increase the noise due to the patient movement.…”

All‐Optical Parametric‐Assisted Oversampling and Decimation for Signal Denoising Amplification

“…For instance, detection of broadband optical signals (with bandwidths > 10 GHz) is required in modern lightwave telecommunication systems, [1] real-time spectroscopy [2,3] and microwave photonics. [4,5] On the other hand, narrowband optical signals (with bandwidths < 1 GHz) are found in applications like biomedical imaging [6] and radio-astronomy. [7] In sensing and ranging applications like LiDARs [8] and optical time-domain reflectometry, [9] the receivers need to acquire extremely weak backscattered signals with bandwidths spanning from the MHz to the GHz regime, depending on the target resolution.…”

Special Issue “Microwave Photonics 2018”

“…Apart from the considerable added value that MWP brings to traditional microwave and radiofrequency systems, this interdisciplinary field holds a promising future in a myriad of emerging areas, such as the Internet of Things [1], medical imaging systems using terahertz waves [8], optical coherence tomography, distributed sensing, wireless and body personal area networks [9], as well as converged fiber-wireless broadband access networks for 5G communications [10].…”