The potential of light in diagnosis and therapy has been long recognised. With the advent of scientific progress in our understanding of light propagation and interaction with tissue and parallel major technological advances in how optical energy can be generated, detected and processed, this potential is being realised. Linking with this trend, this thesis is devoted to the investigation and development of new instrumentation and numerical tools for biophotonics. This work is presented with an emphasis on its application to osseous tissue, although its possible usages are much broader. The introductory chapter gives gives a short historical perspective on the usage of light for diagnosis and therapy, and presents an overview of goals of this thesis, motivating the work and pointing out the main scientific contributions. It also describes the organisation of the book in chapters. Chapter 2 provides the reader with the basic background knowledge that is needed to understand this thesis. It also tries to stress the existing links between the different topics discussed in the book. In particular, some concepts on bone biology are presented, followed by a description of the physics of light propagation in tissue and the basics of the Monte Carlo method used to compute it. Then, the fundamentals of Optical Coherence Tomography are presented, together with basic elements of Planar Waveguide Technology. Chapter 3 contains a description of a novel code for Monte Carlo simulation for arbitrarily complex geometries. This code was required due to the intricate architecture of bone, which was not tractable using available tools. Specifically, it is shown that using a hierarchical space partitioning scheme and simple shape elements, such as triangles, the intersection test between photon and geometry has a very small computational cost. This code has been used in later chapters to simulate light transport in reality based models of trabecular bone. Chapter 4 summarises the research done on light propagation in bone and the effect of bone histology on the average optical properties that can be measured using techniques based on the diffusion approximation. It starts by describing a numerical study where light propagation through models of trabecular bone recovered from micro computed tomography is calculated using the Monte Carlo code described in chapter 3. The simulated time-resolved curves are then fitted using a model based on the diffusion approximation, recovering homogenised parameters. Since it is possible to change the properties postulated in the model for the calcified matrix of bone and marrow separately, we can isolate the role of micro structure easily. The results of this study show that the architecture of bone, together with the properties of the individual phases determine the homogenised properties of tissue. More precisely, the volume fractions are the most important factor, while other morphological parameters such as trabecular connectivity or thickness have a statistically significant, but minor, role as predictors. Using numerical methods, we have also evaluated the value of the average optical properties as predictors of clinically relevant histological and morphological parameters. We have observed that although the optical properties are a direct function of the individual properties of the phases plus the structure, lack of knowledge about the individual constituents obscures the recovery of values such as bone volume fraction or scattering coefficient of the matrix in a general case. However, if multiple wavelengths are combined, this indetermination could be overcome. This investigation was combined with experimental work on the same samples that were used for the numerical study. Making use of ultrafast time-resolved equipment it was possible to reproduce the transmittance signals simulated, and the homogenised optical transport parameters of bone were then calculated using the same type of curve fitting approach. A statistical analysis was done on the relation between these average values and the histological and morphological properties of bone as calculated from micro computed tomography data. It was found that the optical coefficients are statistically significant predictors of the apparent mineral density of bone even at a single wavelength, but the determination is somewhat low. If the mineral density of the calcified matrix is included as a predictor, then the regression for the bone volume fraction gets a much higher determination, underlining the interwoven nature of the relation between optical and histomorphological properties. Work at multiple wavelengths has shown us that a regression with only a synthetic parameter computed from the spectral behaviour of the scattering coefficient has a strong predictive value for the bone mineral density, confirming our observation in the numerical part that spectral measurements can offer a full characterisation of bone. Chapter 5 describes a silicon photonics implementation of a thermo-optic rapid scanning delay line for Optical Coherence Tomography, a crucial component in the implementation of this imaging technology. The proposed device has obvious advantages in terms of cost, reliability and system size and complexity. All these factors are very important for the widespread adoption of OCT in surgical guidance applications, which are the ones that are expected to be most commonly involved in the study of bone tissue. In particular, in this chapter we describe in detail the fabrication of the device, present a thorough analysis of its thermal and optical performance and show experimental performance results. We have demonstrated that this approach is valid and meets the performance requirements demanded by most surgical guidance applications. The ability to produce this crucial element on a general purpose photonic platform, opens the door to full OCT systems on a chip. Chapter 6 discusses the concept of implantable solid state optode systems. We illustrate this idea by presenting preliminary work done on two exemplary applications. The first one is related to monitoring bone growth around a special type of skeletal implant —the spinal cage— and the second one concerns itself with the monitoring and delivery of Photodynamic Therapy for Glioblastoma Multiforme. The first application was explored using a numerical and an in vitro evaluation of the forward problem to estimate light distribution around the implant and compute the expected signal intensities, while the second one had a stronger focus on implementation, with a telemetric single optode implant being constructed and demonstrated. Some conclusions on the results reported throughout the thesis are drawn in the last chapter. There, the relevance of the individual chapters is presented in the context of the thesis. The author’s opinions on the possible future evolution of the topics discussed in this book are also put forward.