  The manipulation of solid states using intense infrared or terahertz light
fields is a pivotal area in contemporary ultrafast photonics research. While
conventional circular polarization has been well explored, the potential of
counterrotating bicircular light remains widely underexplored, despite growing
interest in theory. In the mid-infrared or multi-terahertz region, experimental
challenges lie in difficulties in stabilizing the relative phase between
two-color lights and the lack of available polarization elements. Here, we
successfully generated phase-stable counterrotating bicircular light pulses in
the 10-40 THz frequency range circumventing the above problems. Employing
spectral broadening, polarization pulse shaping with a spatial light modulator,
and intra-pulse difference frequency generation leveraging a distinctive
angular-momentum selection rule within the nonlinear crystal, we achieved
direct conversion from near-infrared pulses into the designed counterrotating
bicircular multi-terahertz pulses. Use of the spatial light modulator enables
programmable control over the shape, orientation, rotational symmetry, and
helicity of the bicircular light field trajectory. This advancement provides a
novel pathway for the programmable manipulation of light fields, and marks a
significant step toward understanding and harnessing the impact of tailored
light fields on matter, particularly in the context of topological semimetals.
