Mode-locked short pulses from an 8 μm wavelength semiconductor laser

Hillbrand, Johannes; Opačak, Nikola; Piccardo, Marco; Schneider, Harald; Strasser, G.; Capasso, Federico; Schwarz, Benedikt

doi:10.1038/s41467-020-19592-1

Cited by 46 publications

(26 citation statements)

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“…The laser radio transmitter concept is more general and could also be implemented using for example quantum dots, which have recently been shown to behave as fast gain media. [ 84 ] In this platform, the concept of RF generation in a laser was already proposed in 2009, [ 85 ] but using saturable absorbers and without exploiting laser gratings nor modulating the carrier to encode information. By combining the methods of harmonic state control, sub‐THz radiation extraction, and high‐frequency modulation for information encoding, research on the laser radio could have an impact in the future of ultrafast sub‐terahertz wireless communications, [ 86–88 ] once the device is properly optimized for better RF coupling [ 81 ] (e.g., by adding a thick dielectric spacer between the top and ground QCL contacts).…”

Section: Harmonic Frequency Combsmentioning

confidence: 99%

Laser Frequency Combs with Fast Gain Recovery: Physics and Applications

Piccardo

Capasso

2021

Laser & Photonics Reviews

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The dynamics of semiconductor lasers with fast gain is generally considered to suppress amplitude modulation, resulting in a frequency‐modulated output. Since their first demonstration of frequency comb operation, quantum cascade lasers—ideal representatives of this class of lasers with fast gain dynamics—were indeed shown to emit frequency‐modulated combs. The understanding of these frequency comb regimes has progressively evolved, being refined from simpler arguments to more advanced theories, considering the role of Kerr nonlinearity and linewidth enhancement factor. By now, the traditional frequency‐modulated combs are rather well understood in quantum cascade lasers, but new types of frequency combs have emerged, reopening interesting physics questions in these lasers. Recent advancements on two open frontiers will be discussed: harmonic frequency combs, characterized by mode skipping of many free spectral ranges, and spatiotemporal structures with solitonic features, recently reported in unidirectional ring cavities. These new types of frequency combs open technological and fundamental perspectives, sprouting new interest in quantum cascade lasers.

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Section: Harmonic Frequency Combsmentioning

confidence: 99%

Laser Frequency Combs with Fast Gain Recovery: Physics and Applications

Piccardo

Capasso

2021

Laser & Photonics Reviews

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“…The individual intermode beatings, which carry the phase information, are isolated using an FTIR spectrometer acting as narrowband spectral filter. The excellent accuracy of SWIFTS for pulse characterisation has been already proven in mode-locked Ti-sapphire 45 , quantum dot 46 and quantum cascade lasers 47 . On the other hand, dual-comb spectroscopy relies on a second reference comb with a slightly different mode spacing.…”

Section: Soliton Formationmentioning

confidence: 93%

Dissipative Kerr solitons in semiconductor ring lasers

Meng,

Singleton,

Hillbrand

et al. 2021

Preprint

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Dissipative Kerr solitons are self-organized optical waves arising from the interplay between Kerr effect and dispersion. They can form spontaneously in nonlinear microresonators pumped with an external continuous-wave laser, which provides the parametric gain for the proliferation of an ultrastable frequency comb. These miniaturized and battery driven microcombs have become a disruptive technology for precision metrology, broadband telecommunication and ultrafast optical ranging. In this work, we report on the first experimental observation of dissipative Kerr solitons generated in a ring cavity with a fast semiconductor gain medium. The moderate quality factor of the ring cavity is compensated by the giant resonant Kerr nonlinearity of a quantum cascade laser, which is more than a million times larger than in Si3N4. By engineering the dispersion of the cavity, we observe the formation of bright dissipative Kerr solitons in the mid-infrared range. Soliton formation appears after an abrupt symmetry breaking between the two lasing directions of the ring cavity. The pump field of the soliton is generated by direct electrical driving and closely resembles the soliton Cherenkov radiation observed in passive microcombs. Two independent techniques shed light on the waveform and coherence of the solitons and confirm a pulse width of approximately 3 ps. Our results extend the spectral range of soliton microcombs to mid-infrared wavelengths and will lead to integrated, battery driven and turnkey spectrometers in the molecular fingerprint region.

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“…Generating ultrashort pulses in such structures is an attempt of pushing the laser out of this favoured state. In the mid-infrared, active mode-locking was accomplished by strongly modulating a small section of the laser cavity close to the repetition frequency [15][16][17] . Although available average powers were limited due to the onset of strong gain saturation, pulse durations as short as 3 ps were reported.…”

mentioning

confidence: 99%