Highly-reflective facet-coated multi-wavelength DFB laser array with exact wavelength spacings

Area of Science:

• Photonics and Optical Engineering
• Semiconductor Lasers
• Integrated Optics

Background:

• Distributed feedback (DFB) laser arrays are crucial for wavelength division multiplexing (WDM) systems.
• Highly reflective (HR) coatings enhance efficiency but introduce random grating phase, affecting wavelength stability and predictability.
• Single-longitudinal-mode (SLM) stability is critical for reliable optical communication.

Purpose of the Study:

• To develop a DFB laser array with precise wavelength spacing and enhanced SLM stability.
• To overcome the limitations of HR coatings in DFB lasers.
• To enable continuous wavelength tuning to standard grids for DWDM applications.

Main Methods:

• Theoretical analysis and experimental validation of a twenty-wavelength DFB laser array.
• Application of the reconstruction-equivalent-chirp (REC) technique for precise wavelength spacing (±0.2 nm error).
• Compensation of random grating phase using a two-section laser structure with a controllable distributed phase shift.

Main Results:

• Achieved precisely spaced wavelengths with an error within ±0.2 nm.
• Demonstrated improved SLM stability and continuous wavelength tunability.
• Obtained high performance metrics: >13 dBm light power, >50 dB side mode suppression ratio, and <-160 dB/Hz relative intensity noise.
• Compact chip size of 4000 × 500 µm².

Conclusions:

• The proposed DFB laser array effectively addresses wavelength predictability and SLM stability issues.
• The combination of REC technique and two-section structure enables precise wavelength control and tuning.
• The laser array's performance makes it suitable for DWDM optical communication and optical I/O applications.