Optical delay method and system

Optical delay method, and related system, comprising: - propagating an optical signal along an optical delay device (10) comprising a first stage (1 1 ) having a variable input coupler (20) and a delay element, an intermediate stage (12) having a variable intermediate coupler (30) and a delay element; an output stage (13) comprising a variable output coupler (40); - setting a coupling ratio of the input (20) and output couplers (40) equal to a value K1 selected among a plurality of at least three values, - setting a coupling ratio of the intermediate coupler (30) equal to a value K2, wherein K1 = sin2(θ) e K2 = sin2 (A * θ) with θ greater than or equal to zero and less than or equal to π/2 and A greater than or equal to 1.5 and less than or equal to 2.5.