Removal of surface-normal spot beam from on-chip 2D beam pattern projecting lasers

Area of Science:

• Photonics
• Optics
• Materials Science

Background:

• Surface-emitting lasers are crucial for optical systems.
• Controlling beam patterns, especially eliminating unwanted orders, is a significant challenge.
• Photonic crystals offer unique light manipulation capabilities.

Purpose of the Study:

• To demonstrate static arbitrary two-dimensional (2D) beam patterns using integrable spatial-phase-modulating surface-emitting lasers.
• To develop a method for removing the surface-normal (0th-order) beam.
• To achieve vertical beam output without the 0th-order component.

Main Methods:

• Utilizing the band edge mode of a 2D photonic crystal as an in-plane resonator.
• Modulating the spatial phase of lightwaves holographically via local hole positional shifts.
• Adjusting the photonic crystal structure's period to the M1 band edge to prohibit vertical diffraction.
• Imposing additional spatial phase modulation to cancel in-plane wavevectors.

Main Results:

• Successfully demonstrated static arbitrary 2D beam patterns.
• Achieved beam patterns without a spot beam in the surface-normal direction.
• Validated the effectiveness of prohibiting vertical diffraction and phase modulation for beam control.

Conclusions:

• The developed spatial-phase-modulating surface-emitting lasers enable precise 2D beam pattern generation.
• The method effectively suppresses the 0th-order beam, enhancing beam pattern quality.
• This technology holds promise for advanced optical systems requiring tailored light emission.