Ultralow noise miniature external cavity semiconductor laser.

Area of Science:

• Photonics and Optical Engineering
• Semiconductor Lasers
• Metrology

Background:

• Advanced optical metrology requires lasers with high spectral purity and stability in compact, robust designs.
• Existing chip-scale lasers lack the sub-100 Hz linewidth necessary for demanding applications.
• Previous integrated laser efforts relied on bulky support equipment, limiting practical use.

Purpose of the Study:

• To demonstrate a heterogeneously integrated, chip-scale semiconductor laser with exceptional spectral purity.
• To achieve sub-100 Hz linewidth in a compact, self-contained laser system.
• To overcome the limitations of current integrated laser technologies for metrology.

Main Methods:

• Heterogeneous integration of semiconductor gain elements with optical microresonators.
• Utilizing optical microresonators as external cavities for noise reduction.
• Fabrication of a monolithic, chip-scale laser device.

Main Results:

• Achieved an integral linewidth of 30 Hz.
• Demonstrated an instantaneous linewidth below 1 Hz.
• Successfully realized a fully chip-scale laser system without external support equipment.

Conclusions:

• This work presents the first demonstration of a chip-scale laser with sub-100 Hz linewidth.
• The developed laser technology is suitable for advanced optical metrology and other applications requiring high spectral purity.
• Heterogeneous integration offers a viable path towards compact, high-performance laser sources.