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dc.contributor.author
Gaulke, Marco
dc.contributor.supervisor
Keller, Ursula
dc.contributor.supervisor
Südmeyer, Thomas
dc.date.accessioned
2023-12-20T11:00:30Z
dc.date.available
2023-12-19T12:54:58Z
dc.date.available
2023-12-20T11:00:30Z
dc.date.issued
2023
dc.identifier.uri
http://hdl.handle.net/20.500.11850/648621
dc.identifier.doi
10.3929/ethz-b-000648621
dc.description.abstract
This dissertation demonstrates advancements in vertical external cavity surface emitting lasers (VECSELs) and semiconductor saturable absorber mirrors (SESAMs) for modelocking applications, using GaSb as a material system. This progression culminates in the demonstration of the first modelocked integrated external cavity surface emitting laser (MIXSEL) for this material system that has gain and absorber integrated into a single semiconductor structure. The operational capabilities of the MIXSEL as free-running, single-cavity dual-comb source make it suitable for dual-comb spectroscopy in a wavelength range which includes molecular absorption features of carbon dioxide. Ultrafast short-wave infrared (SWIR) lasers offer essential functions for many scientific and industrial applications, such as spectroscopy, free-space ranging, and efficient frequency conversion. Semiconductor lasers, with their low cost and compact size, offer increased accessibility, controlled wavelength versatility, and high beam quality when used as disk lasers. Despite these advantages, the development of SESAMs and VECSELs for modelocking has been largely confined to wavelengths below 1.6 µm, employing GaAs and InP semiconductor compounds. SESAMs are a sensible initial choice for acquiring the knowledge to get GaSb-based MBE growth to work. First, comprehensive parameters for growth and characterization are provided for bandgap-engineered structures within the 2 – 2.4 µm spectral range. The SESAMs demonstrate outstanding performance in modelocking applications with a range of lasers including diode-pumped semiconductor, ion-doped solid-state, and thin-disk lasers. Each SESAM is individually optimized for these specific applications and was subsequently provided to our external collaborators for further research and use. In-house grown VECSEL structures emitting at 2 µm are introduced with an approach favoring backside-cooling. This necessitates the removal of the wafer while keeping pace with devices incorporating intracavity heatspreaders. This approach offers significant advantages in modelocking applications where intracavity heatspreaders may pose numerous trade-offs. A record-high, average output power of 810 mW using a non-resonant VECSEL chip optimized for modelocking is achieved. These devices are thoroughly characterized with newly developed setups for spectral and nonlinear gain characterization operating from 1.9 to 3 µm. Small signal gains of more than 5% and broad gain bandwidths of more than 90 nm are demonstrated. Further power scaling is explored at the same wavelength with newly fabricated hybrid metal semiconductor mirrors. These mirrors enhance thermal management, thereby delivering a maximum output power of 3 W. This methodology significantly reduces the thickness of the gain chip from 7.5 µm to 4.7 µm, leading to a reduction in thermal resistance. An alternate method of power scaling, which employs a mirror specifically designed for the incident pump light, yields superior results, enabling us to achieve an output power of up to 6 W. This substantial increase underscores the potential of innovative design solutions in optimizing laser power output. The combination of VECSEL and SESAM enables the first backside-cooled modelocked VECSEL with record-breaking performance giving unprecedented 38-mW ultrashort pulses of 324 fs at around 2 µm. Group delay dispersion (GDD) influences pulse duration and output power across different modelocking regimes, a finding supported by dispersion simulations. Furthermore, operation within the picosecond regime has been successfully demonstrated, exhibiting enhanced power scaling capabilities, giving up to 260 mW and 4.5-ps pulses. Subsequent developments include the improvement of VECSEL chips with integrated dispersion compensation. These can be utilized in a 1:1 modelocking scheme, where the mode sizes on both the absorber and the gain chips are identical, further advancing the capabilities of these laser systems. Upon successful completion of the preliminary work, the comprehensive integration of the absorber into the gain structure led to the fabrication of the first SWIR MIXSEL above 2 µm. This innovative chip has shown efficient modelocking operation: In single-comb operation, it generates pulses of 1.5 ps with an average output power of 28 mW, at a pulse repetition rate of 4 GHz, and centered at a wavelength of 2.035 µm. For dual-comb operation, we employ spatial multiplexing of the cavity using a transmission-operated inverted bisprism, enabling us to achieve an adjustable pulse repetition rate difference, estimated to reach up to 4.4 MHz. This method results in a heterodyne beat, which uncovers a low-noise, down-converted microwave frequency comb, facilitating coherent averaging. Consequently, this compact, single-source SWIR dual-comb is suitably optimized for spectroscopic applications in free-running operation.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
ETH Zurich
en_US
dc.rights.uri
http://rightsstatements.org/page/InC-NC/1.0/
dc.subject
Laser
en_US
dc.subject
Semiconductor
en_US
dc.subject
GaSb
en_US
dc.subject
VECSEL
en_US
dc.subject
SESAM-modelocked lasers
en_US
dc.title
Mapping modelocking progress in GaSb: from VECSEL and SESAM to the dual-comb MIXSEL
en_US
dc.type
Doctoral Thesis
dc.rights.license
In Copyright - Non-Commercial Use Permitted
dc.date.published
2023-12-20
ethz.size
203 p.
en_US
ethz.code.ddc
DDC - DDC::6 - Technology, medicine and applied sciences::600 - Technology (applied sciences)
en_US
ethz.code.ddc
DDC - DDC::5 - Science::530 - Physics
en_US
ethz.code.ddc
DDC - DDC::5 - Science::500 - Natural sciences
en_US
ethz.grant
Mid-infrared optical dual-comb generation and spectroscopy with one unstabilized semiconductor laser
en_US
ethz.identifier.diss
29671
en_US
ethz.publication.place
Zurich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02010 - Dep. Physik / Dep. of Physics::02510 - Institut für Quantenelektronik / Institute for Quantum Electronics::03371 - Keller, Ursula / Keller, Ursula
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02010 - Dep. Physik / Dep. of Physics::02510 - Institut für Quantenelektronik / Institute for Quantum Electronics::03371 - Keller, Ursula / Keller, Ursula
en_US
ethz.grant.agreementno
787097
ethz.grant.fundername
EC
ethz.grant.funderDoi
10.13039/501100000780
ethz.grant.program
H2020
ethz.date.deposited
2023-12-19T12:54:59Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2023-12-20T11:00:32Z
ethz.rosetta.lastUpdated
2024-02-03T08:08:46Z
ethz.rosetta.versionExported
true
ethz.COinS
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