Diamond possesses remarkable physical and chemical properties, and in many ways is the ultimate optical material. For example, it is transparent from the ultra-violet to infrared, has a high refractive index (n = 2.4), strong optical nonlinearity (Kerr and Raman) and a wide variety of light-emitting defects. These properties make diamond a highly desirable material for many applications, including those in quantum and nonlinear photonics, high power optics and optomechanics.
In my talk, I will review the advances in nanotechnology that have enabled fabrication of nanoscale optical devices and chip-scale systems in diamond. Using these approaches we were able to demonstrate high-Q factor diamond photonic crystal cavities (Figure 1a) , frequency combs , and Raman lasers  (Figure 1b). One exciting application of diamond is in the field of quantum information science and technology. At the heart of these applications are diamond’s color centers that have all the essential elements for quantum technology. Recent efforts aimed at coupling of NV , SiV [5, 6] and GeV  color centers to optical (Figure 1a), mechanical (Figure 1c) [8, 9] (Figure 1c) and optomechanical  resonators will be discussed.
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 B. J. M. Hausmann et al, "Diamond Nonlinear Photonics", Nature Photonics, 8, 369 (2014)
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 A. Sipahigil et al, “Single-Photon Switching and Entanglement of Solid-State Qubits in an Integrated Nanophotonic System”, Science, 6314, 847 (2016)
 Michael J. Burek, et al, “Fiber-Coupled Diamond Quantum Nanophotonic Interface.” Phys. Rev. Appl., 8, 2, 024026 (2017)
 Mihir K. Bhaskar, et “Quantum Nonlinear Optics with a Germanium-Vacancy Color Center in a Nanoscale Diamond Waveguide.” PRL, 118, 223603 (2017).
 Young-Ik Sohn*, Srujan Meesala*, Benjamin Pingault*, et al, “Controlling the coherence of a diamond spin qubit through strain engineering.” arXiv:1706.03881
 S. Meesala et al, “Enhanced strain coupling of nitrogen vacancy spins to nanoscale diamond cantilevers.” Phys. Rev. Applied, 5, 034010 (2016)
 M. J. Burek, et al, “Diamond optomechanical crystals.” Optica, 12, 1404 (2016)
Marko Loncar is Tiantsai Lin Professor of Electrical Engineering at Harvard's John A Paulson School of Engineering and Applied Sciences (SEAS), as well as Harvard College Professor. Loncar received his Diploma from University of Belgrade (R. Serbia) in 1997, and his PhD from Caltech in 2003 (with Axel Scherer), both in Electrical Engineering. After completing his postdoctoral studies at Harvard (with Federico Capasso), he joined SEAS faculty in 2006. Loncar is expert in nanophotonics and nanofabrication, and his current research interests include quantum and nonlinear nanophotonics, quantum optomechanics, high-power optics, and nanofabrication. He has received NSF CAREER Award in 2009 and Sloan Fellowship in 2010. In recognition of his teaching activities, Loncar has been awarded Levenson Prize for Excellence in Undergraduate Teaching (2012), and has been named Harvard College Professor in 2017. Loncar is fellow of Optical Society of America, and Senior Member of IEEE and SPIE.