Abstract

Optical arbitrary waveform generation (OAWG) is a desirable technique in many fields of photonics, including high-speed optical communication, coherent control and light detection and ranging (LIDAR). The technique consists in the Fourier synthesis of optical pulses from a mode-locked femtosecond laser, where the phase and amplitude of each individual spectral mode can be independently modulated, this is referred to as line-by-line OAWG, which enables the generation of ultra-short pulses, as well as 100%-duty factor pulse trains [1]. The mode separation of a femtosecond mode-locked laser is typically smaller than one GHz and a modulated continuous wave laser or high-resolution dispersion element (such as virtually-imaged phase array) are usually used in order to resolve and modulate each mode. The target wavelengths of such experiments have been 800 nm and 1.56 μm, so far [2]. This paper describes the development of an ultra-high repetition-rate femtosecond Kerr-lens mode-locked laser centered at a wavelength of 1 μm for the realization of comb resolved OAWG. A 12-GHz (maximum mode separation of 15-GHz) Kerr-lens mode-locked Yb:Y₂O₃ laser [3], was followed by an optical band-pass filter (OBPF) which selected a (several) user-specified longitudinal mode(s) and the manipulation of up to six adjacent longitudinal modes was achieved. The advantage of using an ytterbium (Yb)-doped solid-state laser as an oscillator is the ability to amplify the output to Watt-level after Fourier synthesis, using an Yb-doped fiber amplifier (YDFA).

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