Threshold gain in aperiodic lattice lasers

Folland, Thomas G.; Li, Hua; Chakraborty, Subhasish

doi:10.1364/oe.24.030024

Cited by 4 publications

(1 citation statement)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We can describe structures that have short-, but no long-range order (for example chirped gratings [16] ), long-, but no short-range order (e.g. SSGs [17] , sampled gratings [18] , and quasi-crystals [19] ), or alternatively no order (as in holograms [20,21] ). All these structures have many more degrees of design freedom than a periodic grating, and yet obtaining a desired output is challenging due to the large combination of parameters that can be chosen.…”

Section: Introductionmentioning

confidence: 99%

Multi-frequency coherent emission from superstructure thermal emitters

Tadjer

Caldwell

et al. 2021

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

Long-range spatial coherence can be induced in thermal emitters by embedding a periodic grating into a material supporting propagating polaritons or dielectric modes. However, the emission angle and frequency cannot be defined simultaneously and uniquely, resulting in emission at unusable angles or frequencies. Here, we explore superstructure gratings (SSGs) to control the spatial and spectral properties of thermal emitters. SSGs have long-range periodicity, but a unit cell that provides tailorable Bragg components to interact with light.These Bragg components allow simultaneous launching of polaritons with different frequencies/wavevectors in a single grating, manifesting as additional spatial and spectral bands upon the emission profile. As the unit cell period approaches the spatial coherence 2 length, the coherence properties of the superstructure will be lost. Whilst the 1D k-space representation of the grating provides insights into the emission, the etch depth of the grating can result in strong polariton-polariton interactions. An emergent effect of these interactions is the creation of polaritonic band gaps, and defect states that can have a well-defined frequency and emission angle. In all, our results show experimentally how even in simple 1D gratings there is significant design flexibility for engineering the profile of thermal emitters, bound by finite coherence length.

show abstract

Section: Introductionmentioning

confidence: 99%

Multi-frequency coherent emission from superstructure thermal emitters

Tadjer

Caldwell

et al. 2021

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

show abstract

Optical side-band generation in THz Fabry-Perot laser cavities

Folland

Marshall

et al. 2017

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

Optical nonlinearities in semiconductor laser cavities can be exploited to characterize the properties of laser radiation or perform high speed frequency conversion operations. For example, nonlinear upconversion inside the cavity of quantum cascade lasers allows the use of near infrared optical components 10 to measure high-speed terahertz or mid-infrared optical effects. This letter investigates two aspects of cavity up-conversion which control both the bandwidth and up-converted power; waveguide dispersion and cavity feedback. Specifically, we up-convert multi-mode Fabry Perot terahertz laser emission and detect each THz mode as a sideband signal on an optical carrier in the near infrared. Analysis of these results shows that a single frequency near infrared laser can up-convert terahertz modes spanning a 15 bandwidth of approximately 220 GHz; limited by the group index mismatch between the near infrared and terahertz waves. Secondly, transfer matrix techniques are used to study strong cavity feedback on all three waves, which produces etalon-like resonances in the sideband power. This can significantly enhance the efficiency of the conversion process, in agreement with experiments. It is thus possible to achieve high up-conversion efficiency in quantum cascade lasers for both characterizing broadband laser sources 20 and performing frequency conversion in the near infrared.

show abstract

Optimal defect position in a DFB fiber laser

2021

View full text Add to dashboard Cite

Fiber lasers with compact cavity have numerous potential applications in sensing, communications, and medicine. Distributed feedback (DFB) rare-earth doped fiber lasers based on Bragg gratings with a phase shift are the most promising in this aspect. In this paper, we theoretically study such lasers and carry out a complex-frequency analysis of the DFB cavity modes. Our approach is based on the study of poles of open cavity response function and on the laser rate equations. An optimal defect position in the Bragg grating, which maximizes an output power towards one side, was found with this approach. We show that the optimal defect position depends on the pump power. At the pump level close to the lasing threshold, the defect should preferably appear in the middle of the grating to maximize the one-side output power. At higher pumping, the optimal position of the defect becomes asymmetric. We have found specific variables, which allow for determination of optimal defect position for a large variety of DFB laser configurations.

show abstract

Threshold gain in aperiodic lattice lasers

Cited by 4 publications

References 19 publications

Multi-frequency coherent emission from superstructure thermal emitters

Multi-frequency coherent emission from superstructure thermal emitters

Optical side-band generation in THz Fabry-Perot laser cavities

Optimal defect position in a DFB fiber laser

Contact Info

Product

Resources

About