Broadband lightwave synthesized frequency sweeper using self-induced auto-tracking filter

Area of Science:

• Optoelectronics
• Fiber Optics
• Laser Technology

Background:

• Lightwave synthesized frequency sweepers (LSFS) are crucial for various optical applications.
• The sweeping span of LSFS is often limited by the homogeneous broadening of erbium-doped fiber (EDF).
• Existing methods for broadening the sweeping span can be complex or inefficient.

Purpose of the Study:

• To introduce a new scheme for broadening the sweeping span of LSFS.
• To utilize the spatial-hole-burning effect in unpumped EDF for creating a self-induced auto-tracking filter (SIATF).
• To demonstrate experimental enhancement of LSFS sweeping span and suppression of amplified spontaneous emission (ASE) noise.

Main Methods:

• Implementing a self-induced auto-tracking filter (SIATF) based on the spatial-hole-burning effect in unpumped EDF.
• The SIATF functions as a dynamically adjusting Bragg grating, automatically tracking incident optical signal frequencies.
• Experimental validation of the proposed scheme to measure sweeping span and power change.

Main Results:

• Achieved a broadened sweeping span of 12.48nm for the LSFS.
• Maintained a power change within 3.5dB across the broadened sweeping span.
• Demonstrated effective suppression of amplified spontaneous emission (ASE) noise.
• The 12.48nm sweeping span corresponds to a frequency span of 1.56THz.

Conclusions:

• The proposed SIATF scheme effectively broadens the sweeping span of LSFS beyond the limitations of EDF homogeneous broadening.
• This method offers a practical approach to enhance frequency sweeping capabilities in optical systems.
• The technique simultaneously improves signal quality by reducing ASE noise.