Frequency-Controlled Dot Pattern Projection of Ultrashort Pulse using Optical Phased Array Based on Optical Frequency Comb

An optical phased array (OPA) has recently been developed in tandem owing to the development of optical integrated circuit technology. OPA is an optical analogy to the phased array radar, and the optical waveform can be manipulated by superimposing several phase-controlled beams [1]. However, a broadband OPA has not been realized due to the dispersion of optical waveguides and phase modulators, even though OPA has been developed in various wavelength regions. Thus, the wavefront shaping of phase-locked pulses, such as ultrashort pulses, is unachievable. If the rapid and versatile control of the wavefront of ultrashort pulses is enabled, a wide range of applications, such as multiphoton excitation imaging of samples and beam scanning in broad wavelength ranges, where the CW laser is difficult to attain, is expected.