Raman laser from an optical resonator with a grafted single-molecule monolayer

Surface stimulated Raman scattering-based lasing is achieved using just a monolayer of molecules on silica optical microresonators. Raman-based technologies have enabled many ground-breaking scientific discoveries related to surface science, single-molecule chemistry and biology. For example, researchers have identified surface-bound molecules by their Raman vibrational modes and demonstrated polarization-dependent Raman gain. However, a surface-constrained Raman laser has yet to be demonstrated because of the challenges associated with achieving a sufficiently high photon population located at a surface to transition from spontaneous to stimulated Raman scattering. Here, advances in surface chemistry and in integrated photonics are combined to demonstrate lasing based on surface stimulated Raman scattering (SSRS). By creating an oriented, constrained Si-O-Si monolayer on the surface of integrated silica optical microresonators, the requisite conditions for SSRS are achieved with low threshold powers (200 mu W). The expected polarization dependence of SSRS due to the orientation of the Si-O-Si bond is observed. Owing to the ordered monolayer, the Raman lasing efficiency is improved from similar to 5% to over 40%.