Rayleigh backscattering-based simultaneous linewidth narrowing of a multi-wavelength DFB laser array with an...

Area of Science:

• Photonics and Optical Engineering
• Semiconductor Lasers
• Fiber Optics

Background:

• Multi-wavelength laser arrays are crucial for wavelength-division multiplexing systems.
• Achieving narrow linewidths in such arrays is challenging, especially with arbitrary wavelength spacing.
• Existing linewidth narrowing techniques may lack self-adaptivity or scalability.

Purpose of the Study:

• To experimentally demonstrate simultaneous linewidth narrowing of a multi-wavelength laser array.
• To investigate the self-adaptive nature of Rayleigh backscattering for linewidth reduction.
• To explore the applicability of this method for on-chip integrated photonic devices.

Main Methods:

• Utilizing Rayleigh backscattering from a single high numerical aperture fiber (HNAF).
• Employing a distributed feedback (DFB) semiconductor laser array with four different wavelengths.
• Experimentally verifying linewidth reduction across various wavelength spacings.

Main Results:

• Simultaneous narrowing of instantaneous linewidths from megahertz to kilohertz for all four DFB lasers.
• Demonstrated self-adaptivity of Rayleigh backscattering to arbitrary wavelength spacing.
• Confirmed the method's effectiveness irrespective of equal or unequal wavelength separation.

Conclusions:

• Rayleigh backscattering offers an effective and self-adaptive method for simultaneous linewidth narrowing in multi-wavelength laser arrays.
• The technique is compatible with on-chip waveguides, enabling compact narrow linewidth laser sources.
• This advancement holds promise for improved wavelength-division multiplexing systems and other photonic applications.