| 1. |
- Baghban, Mohammad Amin, 1983-, et al.
(författare)
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Impact of longitudinal fields on second harmonic generation in lithium niobate nanopillars
- 2016
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Ingår i: APL Photonics. - : American Institute of Physics (AIP). - 2378-0967. ; 1:6
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Tidskriftsartikel (refereegranskat)abstract
- An optimized focused ion beam process is used to fabricate micrometer-long LiNbO3 nanopillars with diameters varying between 150 and 325 nm. Polarimetric mappings of second harmonic generation from a wavelength of 850 nm demonstrate the ability to modify the polarization features of the nonlinearresponse through a fine adjustment of the pillar size. The effect is ascribed to the non-negligible contribution of the longitudinal fields associated with sub-wavelength light confinement in the LiNbO3nanopillars. The results also highlight the importance of a fine control over the nanopillar size in order to effectively engineer their nonlinear response.
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| 2. |
- Chang, J., et al.
(författare)
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Detecting telecom single photons with (99.5(-2.07)(+0.5))% system detection efficiency and high time resolution
- 2021
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Ingår i: APL Photonics. - : AIP Publishing. - 2378-0967. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- Single photon detectors are indispensable tools in optics, from fundamental measurements to quantum information processing. The ability of superconducting nanowire single photon detectors (SNSPDs) to detect single photons with unprecedented efficiency, short dead time, and high time resolution over a large frequency range enabled major advances in quantum optics. However, combining near-unity system detection efficiency (SDE) with high timing performance remains an outstanding challenge. In this work, we fabricated novel SNSPDs on membranes with 99.5-(2.07)(+0.5)% SDE at 1350 nm with 32 ps timing jitter (using a room-temperature amplifier), and other detectors in the same batch showed 94%-98% SDE at 1260-1625 nm with 15-26 ps timing jitter (using cryogenic amplifiers). The SiO2/Au membrane enables broadband absorption in small SNSPDs, offering high detection efficiency in combination with high timing performance. With low-noise cryogenic amplifiers operated in the same cryostat, our efficient detectors reach a timing jitter in the range of 15-26 ps. We discuss the prime challenges in optical design, device fabrication, and accurate and reliable detection efficiency measurements to achieve high performance single photon detection. As a result, the fast developing fields of quantum information science, quantum metrology, infrared imaging, and quantum networks will greatly benefit from this far-reaching quantum detection technology.
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| 3. |
- Coetzee, Riaan Stuart, et al.
(författare)
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Low-threshold, mid-infrared backward-wave parametric oscillator with periodically poled Rb : KTP
- 2018
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Ingår i: APL Photonics. - : American Institute of Physics (AIP). - 2378-0967. ; 3:7
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Tidskriftsartikel (refereegranskat)abstract
- We report on the development of a nanosecond mirrorless optical parametric oscillator (OPO) pumped at 1 mu m. The gain medium of the OPO was periodically poled Rubidium-doped KTP with a grating period of Lambda = 509 nm for the first order quasi-phase matching. For grating periods of this length, we demonstrate backward propagation of the signal field and forward propagation of the idler field. To the best of our knowledge, this is the first time such a counter-propagating geometry has been demonstrated in mirrorless OPOs. Pumping with a maximum energy of 6.48 mJ, the OPO yielded an overall conversion efficiency exceeding 53% with signal and idler energies of 1.96 mJ and 1.46 mJ, respectively. The generated signal and idler field spectra were measured to show narrowband linewidths on the order of 0.5 nm. We motivate that such a MOPO is ideal for seeding applications and discuss further improvements and work.
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| 4. |
- Dahlström, Jan Marcus, et al.
(författare)
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Pulse analysis by delayed absorption from a coherently excited atom
- 2019
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Ingår i: Apl Photonics. - : AIP Publishing. - 2378-0967. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- In this tutorial, we provide a short review of attosecond pulse characterization techniques and a pedagogical account of a recently proposed method called Pulse Analysis by Delayed Absorption (PANDA) [S. Pabst and J. M. Dahlstrom, Phys. Rev. A 94, 013411 (2016)]. We discuss possible implementations of PANDA in alkali atoms using either principal quantum number wave packets or spin-orbit wave packets. The main merit of the PANDA method is that it can be used as a pulse characterization method that is free from atomic latency effects, such as scattering phase shifts and long-lived atomic resonances. Finally, we propose that combining the PANDA method with angle-resolved photoelectron detection should allow for experimental measurements of attosecond delays in photoionization from bound wave packets on the order of tens of attoseconds.
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| 5. |
- Elshaari, Ali W., et al.
(författare)
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Dispersion engineering of superconducting waveguides for multi-pixel integration of single-photon detectors
- 2020
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Ingår i: APL Photonics. - : American Institute of Physics (AIP). - 2378-0967. ; 5:11
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Tidskriftsartikel (refereegranskat)abstract
- We use dispersion engineering to control the signal propagation speed in the feed lines of superconducting single-photon detectors. Using this technique, we demonstrate time-division-multiplexing of two-pixel detectors connected with a slow-RF transmission line, all realized using planar geometry requiring a single lithographic step. Through studying the arrival time of detection events in each pixel vs the fabricated slow-RF coplanar waveguide length, we extract a delay of 1.7 ps per 1 mu m of propagation, corresponding to detection signal speeds of similar to 0.0019c. Our results open an important avenue to explore the rich ideas of dispersion engineering and metamaterials for superconducting detector applications.
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| 6. |
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| 7. |
- Huang, Meng, et al.
(författare)
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Continuous-wave Raman amplification in silicon core fibers pumped in the telecom band
- 2021
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Ingår i: APL PHOTONICS. - : AIP Publishing. - 2378-0967. ; 6:9, s. 096105-
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Tidskriftsartikel (refereegranskat)abstract
- Stimulated Raman amplification is observed for the first time in the silicon core fiber (SCF) platform. The SCFs were tapered to obtain sub-micrometer core dimensions and low optical transmission losses, facilitating efficient spontaneous scattering and stimulated Raman amplification using a continuous-wave pump source with milliwatt power levels. A maximum on-off gain of 1.1 dB was recorded at a pump power of only 48 mW with our numerical simulations, indicating that gains up to 6dB are achievable by increasing the fiber length. This work shows that the SCF platform could open a route to producing compact and robust all-fiber integrated Raman amplifiers and lasers across a broad wavelength region.
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| 8. |
- Karki, Khadga Jung, et al.
(författare)
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Different emissive states in the bulk and at the surface of methylammonium lead bromide perovskite revealed by two-photon micro-spectroscopy and lifetime measurements
- 2016
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Ingår i: APL Photonics. - : AIP Publishing. - 2378-0967. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- Two photon photoluminescence (2PPL) from single crystals of methyl ammonium lead bromide (CH3NH3PbBr3, MAPbBr3) is studied. We observe two components in the 2PPL spectra, which we assign to the photoluminescence (PL) from the carrier recombination at the band edge and the recombination due to self-trapping of excitons. The PL Stokes shift of self-trapped excitons is about 100 meV from the band-gap energy. Our measurements show that about 15% of the total PL from regions about 40 μm deep inside the crystal is due to the emission from self-trapped exciton. This contribution increases to about 20% in the PL from the regions close to the surface. Time resolved measurements of 2PPL show that the PL due to band-edge recombination has a life time of about 8 ns while the PL lifetime of self-trapped excitons is in the order of 100 ns. Quantification of self-trapped excitons in the materials used in photovoltaics is important as such excitons hinder charge separation. As our results also show that an appreciable fraction of photo-generated carriers get trapped, the results are important in rational design of photovoltaics. On the other hand, our results also show that the self-trapped excitons broaden the emission spectrum, which may be useful in designing broadband light emitting devices.
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| 9. |
- Kores, Cristine C., et al.
(författare)
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Quasi-phase matching waveguides on lithium niobate and KTP for nonlinear frequency conversion : A comparison
- 2021
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Ingår i: APL PHOTONICS. - : AIP Publishing. - 2378-0967. ; 6:9, s. 091102-
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Tidskriftsartikel (refereegranskat)abstract
- Established waveguide fabrication technologies on lithium niobate (LN) and potassium titanyl phosphate (KTP) were revisited, and a comparative analysis of their performance for type-0 quasi-phase matched second-harmonic generation at 1.55 mu m was provided based on literature data and our simulations. This analysis aided identifying gaps where the waveguide performance is below the theoretical predictions, and the possible reasons are discussed. It provides the reader with a roadmap for choosing the most appropriate waveguide type and material choice between LN and KTP for desired performance of targeted applications.
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| 10. |
- Lancaster, D. G., et al.
(författare)
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An ultra-stable 2.9 mu m guided-wave chip laser and application to nano-spectroscopy
- 2019
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Ingår i: APL Photonics. - : AIP Publishing. - 2378-0967. ; 4:11
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Tidskriftsartikel (refereegranskat)abstract
- We present a configurable guided-wave planar glass-chip laser that produces low-noise and high-quality continuous-wave laser emission tunable from 2.82 to 2.95 mu m. The laser has a low threshold and intrinsic power and mode stability attributable to the high overlap of gain volume and pump mode defined by an ultrafast laser inscribed waveguide. The laser emission is single transverse-mode with a Gaussian spatial profile and M-x,y(2) similar to 1.05, 1.10. The power drift is similar to 0.08% rms over similar to 2 h. When configured in a spectrally free-running cavity, the guided-wave laser emits up to 170 mW. The benefit of low-noise and stable wavelength emission of this hydroxide resonant laser is demonstrated by acquiring high signal-to-noise images and spectroscopy of a corroded copper surface film with corrosion products containing water and hydroxide ions with a scattering-scanning near-field optical microscope.
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