This paper reviews Spatiotemporal Coupled (STc) optical fields including their theoretical background,the experimental configuration for generating STc optical fields,and the current research status of the newly-discovered Spataiotemporal Optical Vortices (STOV) wavepackets. Firstly, we review the origin and early study of STc optical fields,and introduce the theoretical model for describing STc optical fields. To give an example,we show the spatiotemporal evolution of a STOV wavepacket under normal dispersive,anomalous dispersive,and non-dispersive propagation. Under normal dispersive propagation,the STOV wavepacket maintains its ring-like field structure in the spatiotemporal domain. Under non-dispersive propagation, the STOV wavepacket evolves into a diagonal shape. Under anomalous dispersive propagation,the STOV wavepacket has the polarity reversal during the process. Secondly, we describe the typical experimental setup for generating STc optical fields. Although the experimental configuration for realizing STc optical fields shares almost exact the same experimental setup of a standard 4-f pulse shaper,the generating process is more complicated compared with conventional pulse shaping or beam shaping techniques as it involves a subtle interplay between the dispersion and diffraction effects for the generated STc optical fields. We categorize the operation of a STc optical field generator into three different regimes bythe distance between the exit plane of the generator and the observation plane for the generated STc optical fields:1) the" far-field regime"where the observation plane is at several Rayleigh range after the generator;2) the" near-field"regime where the observation plane is within one Rayleigh range;and 3)the" intermediate"regime where the observation plane is placed between"far-field"and" near-field". For each operation regime,we give an example of the experimentally generated STOV wavepacket,namely,the first experimental realization of STOV wavepackets,STOV lattices, and Bessel STOV wavepackets. Thirdly, we give a detailed review about the state-of-art research status of the newly discovered STOV wavepackets including introducingwhy STOV wavepacket has become an interesting research topic for scientists,the demonstration of the conservation of transverse photonic Orbital Angular Momentum(OAM)proved by a nonlinear Second Harmonic Generation(SHG) experiment,and STOV wavepackets superposed with additional spatial photonic singularities. Compared with conventional vortex beam,the spatiotemporal spiral phase carried by a STOV wavepacket enables the photon within the wavepacket to have a pure transverse OAM,which makes STOV wavepacket an interesting tool in many research fields. Besides STOV wavepackets,other STc optical fields generated by this STc optical field generator setup also feature unique photonic properties such as achieving negative refraction,propagating free of diffraction,and propagation in a controllable group velocity. So far,the pulse shaper based STc optical field generation method has seen great success and received tremendous interests by the research community. Despite the great success already achieved,there are much more need to be studied,understood and developed in STc optical fields. With the unprecedented level of control of the spatiotemporal degree of freedoms of light,spatiotemporally sculptured optical fields will significantly enrich the photonics arsenal for scientistsin broad research fields ranging from quantum optics, nanophotonics,spin-photonics and spintronics,optical information transmission and processing,optical spectroscopy,laser driven particle acceleration,and much more beyond.
