Multiple-wavelength distributed-feedback laser arrays with high coupling coefficients and precise channel spacing.

Area of Science:

• Optoelectronics
• Semiconductor Lasers
• Photonics

Background:

• Distributed-feedback semiconductor laser arrays require precise wavelength control.
• Sampled Bragg gratings offer a method for wavelength tuning and channel spacing.
• Phase shifts within gratings can manipulate optical feedback and channel selection.

Purpose of the Study:

• To investigate novel sampled Bragg grating designs for semiconductor laser arrays.
• To achieve precise wavelength spacing and strong coupling coefficients.
• To demonstrate an eight-channel laser array with 100 GHz channel spacing.

Main Methods:

• Fabrication of sampled Bragg gratings with π-phase shifts.
• Dividing sampling periods into two equal sections with a π-phase shift.
• Utilizing single electron beam lithography for fabrication.

Main Results:

• Elimination of zeroth-order reflection by using two π-phase-shifted sections.
• Enhancement of ±1st-order channels with the two-section π-phase shift design.
• Successful fabrication of an eight-channel laser array with 100 GHz channel spacing.

Conclusions:

• Special sampled Bragg grating designs enable precise control over laser array characteristics.
• The π-phase shift technique effectively enhances desired diffraction orders and suppresses unwanted ones.
• This method provides a viable route for fabricating multi-channel laser arrays with specific frequency spacing.