Fluorescence spectroscopy, optical coherence tomography (OCT), and Raman spectroscopy are foundational optical modalities that enable noninvasive access to molecular, structural, and biochemical information in biological systems. Fluorescence detects dynamic molecular interactions with high sensitivity; OCT provides real-time, micrometer-scale structural imaging; and Raman spectroscopy delivers chemically specific, label-free molecular fingerprints. Together, these techniques form a powerful multimodal toolkit for advancing biomedical science and clinical care. Work in this space has focused on engineering portable imaging systems, designing targeted and multimodal contrast agents, and developing implantable nanosensors for in vivo molecular monitoring. These technologies have been translated to applications in early cancer detection, intraoperative decision-making, and therapeutic response assessment. By bridging basic optical science with real-world diagnostics, these tools continue to shape precision medicine and the future of patient-centered healthcare.