APL Photonics

Journal: APL Photonics

Publisher

American Institute of Physics

ISSN

2378-0967

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Publications1 - 10 of 19

Anti-correlation phenomena in quantum cascade laser frequency combs
Chomet, Baptiste; Gabbrielli, Tecla; Gacemi, Djamal; et al. (2023)
APL Photonics
In quantum cascade laser frequency combs, the intensity distribution of the optical spectrum can be split into two well-separated lobes of longitudinal modes that, even when far apart, have a common phase relation and preserve equal frequency separation. The temporal dynamics of two lasers emitting at 4.4 and 8.1 μm operating in this bilobed regime are here investigated. The laser intensity shows a peculiar temporal behavior associated with the spectral features whereby, every half a round-Trip, the total emitted power switches from one lobe to the other, with a perfect temporal anti-correlation. The anti-correlation between the lobes is also observed in the intensity noise figure of the emission. This coherent phenomenon arises from gain nonlinearities induced by spatial hole burning and the extremely fast gain dynamics typical of quantum cascade lasers.
Special topic on synthetic gauge field photonics
Bandres, Miguel A.; Zilberberg, Oded; Sukhorukov, Andrey (2022)
APL Photonics
Ultra-low noise spectral broadening of two combs in a single ANDi fiber
Camenzind, Sandro L.; Sierro, Benoît; Willenberg, Benjamin; et al. (2025)
APL Photonics
Developing high-brightness, low-noise supercontinuum (SC) sources is critical for a variety of ultrafast photonics applications. A key challenge in achieving low-noise operation is the suppression of incoherent nonlinear effects and the associated noise amplification. All-normal dispersion (ANDi) SC sources exhibit considerably reduced noise levels compared to conventional soliton-based methods, but their previous lowest-noise demonstrations were limited by amplified spontaneous emission from amplified femtosecond pump laser systems, which seeds incoherent nonlinearities and degrades SC quality. Consequently, the ultimate low-noise limits of coherent SC generation have not been demonstrated by experimental results. Here, we report ultra-low noise, shot-noise-limited SC generation by directly driving the SC process with the un-amplified output of a high-power dual-comb Yb:CALGO oscillator centered at 1053 nm. The resulting SC combs each have a spectrum spanning 820-1280 nm (−20 dB), 1.6 W average power, 1.03 GHz repetition rate, and a comb-line power of ≈10 μW. We conduct detailed noise studies of the SC by analyzing various ≈15-nm-wide spectral bands. All bands reach a shot-noise-limited relative intensity noise below −160 dBc/Hz at 100-kHz to few-MHz noise frequencies. Furthermore, the central spectral bands exhibit an unprecedented noise suppression of the pump laser’s technical noise above ≈2 kHz by >20 dB, which agrees with our semiclassical simulations. Finally, we simultaneously couple both combs into a single ANDi fiber to generate a dual-comb SC with highly symmetric spectra and correlated noise properties between the combs. Coherently averaged linear optical sampling measurements on the dual-comb SC exhibit a high signal-to-noise ratio, showcasing its potential for real-time spectroscopic measurements.
Non-resonant optical injection locking in quantum cascade laser frequency combs
Parriaux, Alexandre; Komagata, Kenichi N.; Bertrand, Mathieu; et al. (2025)
APL Photonics
Optical injection locking of the repetition frequency of a quantum cascade laser frequency comb is demonstrated using intensity modulated near-infrared light at 1.55 mu m, illuminating the front facet of the laser. Compared to the traditional electrical modulation approach, the introduced technique presents benefits from several perspectives, such as the availability of mature and high bandwidth equipment in the near-infrared, circumvents the need for dedicated electronic components for the quantum cascade laser, and allows a direct link between the near and mid-infrared for amplitude to frequency modulation. We show that this stabilization scheme, used with moderate near-infrared power of a few milliwatts, allows for a strong reduction of the frequency noise. We also perform a full characterization of the mechanism and provide evidence that the locking range follows Adler's law. A comparison of our results with those in recent literature indicates that the optical approach leads to better performance compared to the traditional method, which we expect to benefit mid-infrared spectroscopy and metrological applications.
Coherent control of mid-infrared frequency comb by optical injection of near-infrared light
Komagata, Kenichi N.; Parriaux, Alexandre; Bertrand, Mathieu; et al. (2023)
APL Photonics
We demonstrate the use of a low power near-infrared laser illuminating the front facet of a quantum cascade laser (QCL) as an optical actuator for the coherent control of a mid-infrared frequency comb. We show that with appropriate current control of the QCL comb and intensity modulation of the near-infrared laser, a tight phase lock of a comb line to a distributed feedback laser is possible with 2 MHz of locking bandwidth and 200 mrad of residual phase noise. A characterization of the whole scheme is provided, showing the limits of the electrical actuation, which we bypassed using the optical actuation. Both comb degrees of freedom can be locked by performing electrical injection locking of the repetition rate in parallel. However, we show that the QCL acts as a fast near-infrared light detector such that injection locking can also be achieved through modulation of the near-infrared light. These results on the coherent control of a QCL frequency comb are particularly interesting for coherent averaging in dual-comb spectroscopy and for mid-infrared frequency comb applications requiring high spectral purity.
Microring quantum cascade surface emitting lasers
Stark, David; Beck, Mattias; Faist, Jérôme (2025)
APL Photonics
We miniaturize a vertically coupled in-plane whispering gallery mode cavity incorporating a quantum cascade gain medium, aiming to realize the mid-infrared counterpart to the vertical cavity surface emitting laser. Building on previous work with linear microcavities, we introduce a new type of quantum cascade surface emitting laser (QCSEL) by miniaturizing a buried heterostructure ring cavity. At wavelengths of 4.5 and 8 μm, we investigate the optical losses for decreasing ring diameters while benchmarking the device performance against linear microcavities. We achieve an equivalent mirror reflectivity of 0.95 and demonstrate lasing with ring diameters as small as 50 μm. Finally, we report a continuous-wave threshold power dissipation of 274 mW for a 100 μm diameter ring QCSEL, characterized on wafer level at 20 °C.
Ultra-high-Q phononic resonators on-chip at cryogenic temperatures
Kharel, Prashanta; Chu, Yiwen; Power, Michael P.; et al. (2018)
APL Photonics
Long-lived, high-frequency phonons are valuable for applications ranging from optomechanics to emerging quantum systems. For scientific as well as technological impact, we seek high-performance oscillators that offer a path toward chip-scale integration. Confocal bulk acoustic wave resonators have demonstrated an immense potential to support long-lived phonon modes in crystalline media at cryogenic temperatures. So far, these devices have been macroscopic with cm-scale dimensions. However, as we push these oscillators to high frequencies, we have an opportunity to radically reduce the footprint as a basis for classical and emerging quantum technologies. In this paper, we present novel design principles and simple microfabrication techniques to create high performance chip-scale confocal bulk acoustic wave resonators in a wide array of crystalline materials. We tailor the acoustic modes of such resonators to efficiently couple to light, permitting us to perform a non-invasive laser-based phonon spectroscopy. Using this technique, we demonstrate an acoustic Q-factor of 2.8 × 107 (6.5 × 106) for chip-scale resonators operating at 12.7 GHz (37.8 GHz) in crystalline z-cut quartz (x-cut silicon) at cryogenic temperatures.
Quantum cascade lasers as broadband sources via strong RF modulation
Cargioli, Alessio; Piciocchi, Diego; Bertrand, Mathieu; et al. (2024)
APL Photonics
In this work, we demonstrate that in a regime of strong modulation, by generating pulses of the length of the order of a few cavity lifetimes (hundreds of ps), a broadband quantum cascade laser can be driven to lase on a bandwidth (250 cm⁻¹) limited by the gain. In addition, the amplitude noise of the radiation was shown to be limited by the detector. A laser linewidth study has been performed under different operating conditions, finding values spanning from 20 to 800 MHz, indicating a trade-off between emission bandwidth, amplitude stability, and coherence. The pulsed intensity of the output arises from the gain switching dynamics of the laser, while the self-seeded nature of the emission is responsible for the low amplitude noise and the relatively narrow linewidth of the individual spectral lines of the multimode emission.
Programmable non-Hermitian photonic quantum walks via dichroic metasurfaces
Savarese, Paola; Bansal, Sarvesh; Ammendola, Maria Gorizia; et al. (2025)
APL Photonics
The evolution of a closed quantum system is described by a unitary operator generated by a Hermitian Hamiltonian. However, when certain degrees of freedom are coupled to an environment, the relevant dynamics can be captured by non-unitary evolution operators, arising from non-Hermitian Hamiltonians. Here we introduce a photonic platform that implements non-unitary quantum walks, commonly used to emulate open-system dynamics, in the synthetic space of light transverse momentum. These walks are realized by propagating light through a series of dichroic liquid-crystal metasurfaces that impart polarization-dependent momentum shifts. The non-unitary behavior stems from dichroic dye molecules with polarization-dependent absorption, whose orientation is coupled to that of the liquid crystals. We demonstrate multiple walks up to five time steps, with adjustable levels of dichroism set by the metasurface voltage, which is controlled remotely. This discrete-time process maps onto two-band tight-binding models with reciprocal yet non-Hermitian nearest-neighbor couplings, corresponding to a less-studied class of non-Hermitian systems. Our platform broadens the range of optical simulators for controlled investigations of non-Hermitian quantum dynamics.
500 GHz plasmonic Mach-Zehnder modulator enabling sub-THz microwave photonics
Burla, Maurizio; Hoessbacher, Claudia; Heni, Wolfgang; et al. (2019)
APL Photonics
Broadband electro-optic intensity modulators are essential to convert electrical signals to the optical domain. The growing interest in terahertz wireless applications demands modulators with frequency responses to the sub-terahertz range, high power handling, and very low nonlinear distortions, simultaneously. However, a modulator with all those characteristics has not been demonstrated to date. Here, we experimentally demonstrate that plasmonic modulators do not trade-off any performance parameter, featuring—at the same time—a short length of tens of micrometers, record-high flat frequency response beyond 500 GHz, high power handling, and high linearity, and we use them to create a sub-terahertz radio-over-fiber analog optical link. These devices have the potential to become a new tool in the general field of microwave photonics, making the sub-terahertz range accessible to, e.g., 5G wireless communications, antenna remoting, Internet of Things, sensing, and more.

Publications1 - 10 of 19

Journal: APL Photonics

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