Emma Martin

EECS Department, University of California, Berkeley

Technical Report No. UCB/

December 1, 2025

Semiconductor optoelectronic devices such as LEDs, solar cells, and lasers play a fundamental role in our information technology era and are poised to revolutionize applications ranging from displays, energy-efficient high-speed communications, and artificial intelligence hardware. Photonic crystal surface-emitting lasers (PCSELs) exhibit distinct advantages over more conventional lasers of similar footprint, including higher output power and superior beam quality. By leveraging the symmetry and tunability inherent in photonic crystal structures, PCSELs can support unexpected wave phenomena that enable further advances in laser functionality. Suspended photonic crystal apertures, in particular, are ideal platforms for demonstrating these effects, as they maximize optical mode confinement and preserve symmetries. Despite the advantages of the suspended platform, an effective scheme for electrically injecting such apertures has not yet been realized. Conventional approaches to controlling light with electrical signals constrain symmetry, reduce refractive-index contrast, and increase the complexity and footprint of PCSELs and other optoelectronic devices.

In this dissertation, I first introduce advances in optically pumped suspended PCSEL membranes that operate with distinct topological properties. I present a scaleinvariant laser, known as the Berkeley Surface Emitting Laser (BerkSEL), which allows for single-mode operation from the laser cavity without compromising device size or output power. I also present a beam-steering laser with a tunable emission angle achieved by shifting Bound States in the Continuum (BIC) modes in momentum space. The fabrication methods implemented to realize these suspended laser cavities are described in detail. Next, I introduce a monolithic design and fabrication process that enables the room-temperature electrical activation of a PCSEL cavity without compromising optical confinement and symmetry constraints. This platform, which achieves electrical activation at the unit cell level via a nano-post array beneath the photonic crystal cavity, provides a minimally perturbative electrical path while maintaining the maximum refractive-index contrast between the optical mode and the surrounding media. This result establishes a new paradigm for minimally invasive, nano-scale electrical control of photonic states.

Advisors: Boubacar Kanté

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BibTeX citation:

@phdthesis{Martin:32016,
    Author= {Martin, Emma},
    Title= {Fabrication of Scalable and Electrically Injected Photonic Crystal Surface-Emitting Lasers},
    School= {EECS Department, University of California, Berkeley},
    Year= {2025},
    Month= {Dec},
    Number= {UCB/},
    Abstract= {Semiconductor optoelectronic devices such as LEDs, solar cells, and lasers play a fundamental role in our information technology era and are poised to revolutionize applications ranging from displays, energy-efficient high-speed communications, and artificial intelligence hardware. Photonic crystal surface-emitting lasers (PCSELs) exhibit distinct advantages over more conventional lasers of similar footprint, including higher output power and superior beam quality. By leveraging the symmetry and tunability inherent in photonic crystal structures, PCSELs can support unexpected wave phenomena that enable further advances in laser functionality. Suspended photonic crystal apertures, in particular, are ideal platforms for demonstrating these effects, as they maximize optical mode confinement and preserve symmetries. Despite the advantages of the suspended platform, an effective scheme for electrically injecting such apertures has not yet been realized. Conventional approaches to controlling light with electrical signals constrain symmetry, reduce refractive-index contrast, and increase the complexity and footprint of PCSELs and other optoelectronic devices.

In this dissertation, I first introduce advances in optically pumped suspended PCSEL membranes that operate with distinct topological properties. I present a scaleinvariant laser, known as the Berkeley Surface Emitting Laser (BerkSEL), which allows for single-mode operation from the laser cavity without compromising device size or output power. I also present a beam-steering laser with a tunable emission angle achieved by shifting Bound States in the Continuum (BIC) modes in momentum space. The fabrication methods implemented to realize these suspended laser cavities are described in detail. Next, I introduce a monolithic design and fabrication process that enables the room-temperature electrical activation of a PCSEL cavity without compromising optical confinement and symmetry constraints. This platform, which achieves electrical activation at the unit cell level via a nano-post array beneath the photonic crystal cavity, provides a minimally perturbative electrical path while maintaining the maximum refractive-index contrast between the optical mode and the surrounding media. This result establishes a new paradigm for minimally invasive, nano-scale electrical control of photonic states.},
}

EndNote citation:

%0 Thesis
%A Martin, Emma 
%T Fabrication of Scalable and Electrically Injected Photonic Crystal Surface-Emitting Lasers
%I EECS Department, University of California, Berkeley
%D 2025
%8 December 1
%@ UCB/
%F Martin:32016