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This thesis presents the development of novel solid-state laser sources, divided into two primary areas: a new mode-locking scheme demonstrated using Nd:YVO4 lasers with an intra-cavity nonlinear medium, producing bright and dark mode-locking, and a laser source based on a backward wave optical parametric oscillator (BWOPO) for CO2 absorption measurements. The mode-locking research is detailed in three papers. The initial work demonstrates the first realization of dark pulse mode-locking in a solid-state laser. A periodically poled KTiOPO4 (PPKTP) crystal placed within a continuous-wave (CW) Nd:YVO4 laser operating at 1064 nm where a Yb:KYW femtosecond laser at 1040 nm was focused in to the nonlinear crystal. The phase matched sum-frequency mixing (SFM) in the crystal acted as a time dependent loss. When the CW laser’s cavity round trip time matched the femtosecond repetition rate, stable dark pulses with a 10 ps duration and 90% modulation depth were formed, minimizing SFM loss. In the second study, it was shown that the bright-dark pulse configuration could be passively generated by replacing the femtosecond laser with a CW laser at 1342 nm. This setup enabled interaction through cross-amplitude modulation (XAM) in the PPKTP crystal. A dichroic mirror allowed both lasers to share the cavity section containing the nonlinear medium, while the independently diode-pumped laser crystals were placed in separate sections. By matching the cavity round trip times, synchronous bright-dark pulses were formed: 250 ps bright pulses at 1064 nm and dark pulses at 1342 nm, effectively minimizing SFM losses. The third work further refined this setup by modifying the cavity to increase intra-cavity intensity, leading to cascaded second-order nonlinearity Kerr lens mode-locking. The increased intensity from XAM enabled significant pulse compression for the 1064 nm pulses. The 1064 nm cavity produced 14 ps bright pulses, with correspondingly compressed dark pulses. Lastly, this thesi, Denna avhandling behandlar utvecklingen av nya ljuskällor baserat på fasta-tillståndslasrar och kan delas upp i två huvudområden: en ny modlåsningsmekanism demonstreras med Nd:YVO4-lasrar och ett intrakavitärt ickelinjärtmaterial som kan producera ljus och mörk modlåsning, och en laser baserad på en bakåtvågs optisk parametrisk oscillator (BWOPO) för att mäta CO2. Modlåsningsforskningen är uppdelad i tre artiklar. I den första artikeln utvecklade vi den första mörkpulsmodlåsningskällan baserad på fasta-tillståndslasrar. Systemet använde en periodiskt polad KTiOPO4 (PPKTP) inuti en kontinuerlig (CW) Nd:YVO4-laser vid 1064 nm, tillsammans med en femtosekundspulsad Yb:KYW laser vid 1040 nm. Kristallen fasmatchade summafrekvensgenerering (SFM) mellan de två ljuskällorna, vilket gav upphov till en tidsberoende förlust. När CW-laserns rundtrippstid matchade femtosekundslaserns pulser, formades stabila mörka pulser med en längd på 10 ps och ett moduleringsdjup på 90%. I den andra artikeln visade vi att de mörka och ljusa pulserna kunde genereras passivt om femtosekundslasern byttes ut mot en CW-laser vid 1342nm. Kristallens SFM motsvarade en korsamplitudmodulering (XAM), vilket gjorde det möjligt att skapa pulser. En dikroisk spegel användes för att dela upp kaviteterna i två delar: en delad arm där den intrakavitära icke-linjära kristallen var placerad, och en separat del där de självständigt diodpumpade laserkristallerna placerades. Genom att matcha rundtrippstiden skapades synkrona, ljusa och mörka pulser; 250 ps ljusa pulser formades i 1064 nm lasern och mörka pulser i 1342 nm-lasern. På detta sätt kunde SFM och därmed förlusterna för lasrarna minimeras. I den tredje artikeln vidareutvecklade vi modlåsningen genom att öka den intrakavitära intensiteten, vilket ledde till en kaskaderad andra ordningens icke-linjäritet i form av Kerr-lins-modlåsning. Den ökade intensiteten från XAM möjliggjorde en kompression av 1064 nm-pulserna. De ljusa pulserna i 1064 nm-lasern blev 1, QC 2024-11-19

Silica fibers are highly desired due to their robustness and easy integration with existing infrastructure. Although fabrication of silica gain fibers can be performed using well-established methods e.g., Modified Chemical Vapor Deposition (MCVD), each production cycle can be time-consuming and expensive. Additive manufacturing (AM) on the other hand is an attractive way of fabrication, where reduced waste and short cycles are widely recognized. Today, AM is commonly used to make functional components and prototypes., Part of ISBN 9798350345995QC 20231116

The pursuit of advanced fiber laser technologies has driven research toward unconventional manufacturing techniques. In this work, we present an erbium-doped fiber laser made using powder-based additive manufacturing. An Er3+/Al3+ co-doped silica glass rod was printed using laser powder deposition and then used as the core material in a fiber preform. The fiber drawn from the preform exhibited the complete, desired functionality linked to Er3+ doping. To demonstrate this, a standing wave laser cavity was formed with the feedback attained from the cleaved ends of the manufactured fiber. The high quality of the fiber is showcased through a low background loss, single-mode operation, a 9.4% laser slope efficiency, and an output of 4.5 mW, limited by the available pump power. This proof-of-concept opens up promising areas for rapid fabrication and development of high-performance fibers and fiber lasers., QC 20231215, 2022-06180

A Nd:YVO4 laser operating at 1064 nm generating a stable mode-locked train of 10 ps-long dark pulses with a 211 MHz repetition rate is presented. The mode-locking relies on a periodic loss modulation produced by intra-cavity sum-frequency mixing with a synchronous bright-pulse train from a mode-locked femtosecond Yb:KYW laser at 1040 nm. A modulation depth of 9050 was achieved for the dark pulses, confirmed by cross-correlation measurements. The ultrafast loss modulation injects power into the Nd:YVO4 laser cavity modes beyond the laser gain bandwidth. At proper laser cavity length, the detuning interaction of these modes with the lasing modes leads to the generation of periodic ultra-fast transients at frequencies above 1.5 THz., QC 20220328

A new technique for mode-locking is demonstrated based on two lasers sharing one leg for sum-frequency generation. When the two lasers had equal round trip time one will produce bright pulses and the other dark pulses. Both lasers used Nd:YVO4 as the gain material, but operated at different wavelengths, namely 1064 nm and 1342 nm. In the present configuration, sub-250 ps pulses were generated at a repetition rate of 276 MHz with an output power of 70 mW. With appropriate choice of round trip loss at the two wavelengths it was possible to choose which laser was generating the bright pulses., QC 20221202

We demonstrate a method for rapid prototyping of optical fibers. Silica-based glass rods were 3D printed using laser powder deposition. Different doping of the 3D printed rods is evaluated, including alumina, titania, and erbium-doped glass. The rods were subsequently used as the core material in preforms with optical fibers drawn using a laser-based draw tower. A transmission loss of 3.2 dB/m was found for a fiber with 1 wt% titania doped core and pure silica cladding. Using this fabrication method, prototyping from powder to optical fiber could be achieved within a few hours., QC 20220811

We utilized a powder-based, 3D printing technique for prototyping optical fibers. Co-doped silica rods were printed using sub-micron powders with various compositions. The rods were sleeved and drawn into fibers. Ti/Al/Er-co-doped fibers are demonstrated., Part of ISBN 9781557528209SyskonpostNot duplicate with DiVA 1763568QC 20230622

Light Detection and Ranging (LIDAR) is a powerful imaging technique. By utilising a superconducting nanowire single photon detector (SNSPD) we construct a 3D scanning LIDAR system operating with eye-safe infrared laser pulses and millimeter precision., Part of ISBN 9781957171050SyskonpostNot duplicate with DiVA 1764020QC 20230622

A new technique for mode-locking through sum-frequency generation is presented. The technique produced 200 ps long 1064 nm pulses in a coupled-cavity system with two Nd:YVO4 crystals and a PPRKTP phase-matched for sum-frequency generation., Part of ISBN 9781557528209SyskonpostNot duplicate with DiVA 1764025QC 20230622

Part of proceedings: ISBN 978-1-6654-1876-8QC 20220214

While the development of bright pulses produced in free space devices can be found in a large set of applications and research equipment all over the world. The production of dark pulses in a free-space device has not been shown prior to this work. In this work a method of producing free space mode-locked laser in a straight laser cavity using intra-cavity loss induced by periodic nonlinear interactions mediated by a mode-locked source. We are able to show the existence of a dark pulse propagating inside of the cavity. An extensive analysis of the generation of the dark pulse is made using a homemade cross correlator. A symmetric dark pulse with a 10 ps width is achieved with a 90% modulation depth. This work will be used in a continued project involving passive two-color pulse synchronization., Framtagningen av ljusa pulser i kristall baserade lasrar finns i en stor utsträckning av tillämpningar inom forskning och industri. Utvecklandet av mörkpulskällor i kristall baserade kaviteter har till vår kunskap inte tagits fram. I detta arbete presenteras en metod att utveckla en modlåst mörkpuls laser i en rak kavitet som utnyttjar intrakavitär förlust som periodiskt induceras av en ickelinjär interaktion som styrs av en ljus modlåst källa. Vi kan visa att en mörk puls propagerar inuti kaviteten. En utförlig analys och experiment med hjälp av en hemagjord korskorrelator belyser hur den mörka pulsen kan formas. En symmetrisk mörk puls formas med en 10 ps bredd och över 90 % modulations djup. Detta arbete kommer användas i ett framtida projekt inom passiv tvåfärgs puls synkronisation.

Enkelfotonkällor är ett aktivt forskningsområde på grund av deras potentiella användning inom kvantteknologi. På grund av deras mikroskopiska storlek är de dock svåra att producera på ett tillförlitligt sätt. Det finns flera olika processer som behöver förbättras för att fullkomna tillverkningen av enkelfotonkällor. En sådan process som måste förbättras för att tillverka en specifik typ av enkelfotonkälla är kemisk etsning, avlägsnandet av material från ett substrat med hjälp av en kemisk lösning. Syftet med detta projekt har varit förbättra detta produktionssteg. Detta uppnåddes genom att konstruera en förbättrad uppställning som ökade etsningens stabilitet och gjorde det möjligt att övervaka processen. Denna uppställning bestod av en uppsättning linser och bländare som fungerade som ett mikroskop med ett långt objektavstånd och en liten dator med en kamera som är ansluten och kan övervaka processen. Den nya uppställningen förbättrade resultaten av etsningen och förmågan att övervaka etsningen gav en djupare insikt om hela processen. Detta ledde till en ytterliggare förbättring i form av att minska omrörningen av den kemiska lösningen vilket ledde till en jämnare etsningsyta., Single photon sources are an active field of research due to their great potential in photonic quantum technologies. One of their biggest advantages compared to other light sources is their ability to generate single photons on demand. However, their emission profile, emitting photons in all directions, leads to severe losses. Therefore, complex photonic structures such as cavities, antennas, waveguide have been used to increase the brightness of single photon sources. Due to their nanoscale size however single photon sources are difficult to produce reliably and there are various processes that need to be improved to perfect any manufacturing of such nano-engineered single photon sources. One such process for a specific type of single photon source is the process of wet chemical etching, the removal of specific materials from a substrate with the help of chemical solutions. The purpose of this project has been too improve this production step. This was achieved by constructing a new setup that increased the stability of the etching process and made it possible to better monitor the process. This new setup consisted of a system of lenses and apertures that act as a long working distance microscope combined with a small computer with a camera module attached to capture the images of the ongoing process. This new setup improved the results of the etching and the ability to monitor its progress provided deeper insight of the etching process. This led to an improvement of the etching process itself by lowering the agitation of the chemical solution which led to a more even etching surface.

Submitted to Optical Materials Express, finally published in DOI 10.1364/OME.459400QC 20220530

QC 20220601