Frequency comb

Fiber laser

Ultrashort pulse

Materials science

Optoelectronics

Picosecond

Mode-locking

Telecommunications

Combinatorics

Physics

Multiplexing

Mathematics

Optics

Harmonic

Acoustics

Quantum mechanics

Computer science

Dual loop

Microwave

Loop (graph theory)

Laser

Phase noise

Injection locking

Optics Letters

The active mode-locking (AML) technique has been widely used in erbium-doped fiber lasers to generate picosecond pulse trains. Here we propose a novel active mode-locking dual-loop optoelectronic oscillator (AML-DL-OEO), which can generate microwave frequency comb (MFC) signals with adjustable comb spacings. Based on this scheme, the order of harmonic mode-locking is dramatically decreased for a certain AML driving frequency compared with a single-loop AML-OEO. Thus, the supermode noise caused by harmonic mode-locking can be efficiently suppressed. In addition, the sidemodes are well suppressed by the dual-loop architecture. An experiment is performed. MFC signals with different comb spacings are generated under fundamental or harmonic mode-locking states. AML-DL-OEO systems with different length differences between two loops are implemented to evaluate supermode noise suppression capability. The performance of the generated MFC signals is recorded and analyzed.

Supermode noise suppression with polarization-multiplexed dual-loop for active mode-locking optoelectronic oscillator