  We theoretically study valley-filtering in pristine graphene irradiated by
bicircular counter-rotating laser drive. The dynamical symmetry of the graphene
and laser drive disrupts graphene's inversion symmetry, which results distinct
quasi-energy states and Floquet band occupations in the two valleys.
Controlling the relative phase between the bicircular laser drive ultimately
allows to blocks the contribution from one valley while allowing the opposite
valley currents in the system. For practical realization of valley-based
device, we propose configurational setup for valley filters and valley valve
consisting of two graphene nanoribbons irradiated by two bicircular
counter-rotating laser drives with a relative phase shift. It is observed that
the relative phase between the two bicircular laser drives offer a control knob
to generate valley-selective currents and transport responses with very high
efficiency by an all-optical way. In addition, our findings about valley filter
and valley valve are robust against moderate disorder and modest changes in
driving laser parameters. Present work opens an avenue to realise light-based
valleytronics devices in reality.
