Nanoscale science is playing an increasingly important role in developing future technologies for information systems including computing, telecommunications, display, high-resolution imaging and sensing. Optical and photonic technologies are recognized as enablers in most of these applications. However, construction of artificially engineered nanostructured optical and optoelectronic materials, resonant nanostructures such as photonic crystals, and integrated nanophotonic active and passive devices is one of the most challenging tasks. In order to improve device performance, good characterization tools for structural and functional testing of nanophotonic devices are required. One technique that may be promising for improving visualization, imaging, and characterization tools is based on coherent Near-field Scanning Optical Microscopy (NSOM). This instrument enables quantitative detection of the complex amplitude of the optical near-field of various nanophotonic devices on nanoscale. Amplitude, phase and topography are measured simultaneously by combining an NSOM and a heterodyne interferometer. Its continuous wave (CW) design has been extended with ultra-short femtosecond laser pulses at 1550 μm to investigate phenomena in the optical near field with femtosecond time resolution. The evanescent light of a short pulse has been observed in a waveguide, allowing the investigation of both its spatial and temporal device characteristics.