| 461. |
- Lorences Riesgo, Abel, 1987, et al.
(författare)
-
Self-homodyne 24×32-QAM superchannel receiver enabled by all-optical comb regeneration using Brillouin amplification
- 2016
-
Ingår i: Optics Express. - : The Optical Society. - 1094-4087 .- 1094-4087. ; 24:26, s. 29714-29723
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate and characterize an all-optical self-homodyne (SH) frequency superchannel enabled by comb regeneration at the receiver. In order to generate the superchannel, we use a frequency comb with 26 carriers spaced by 25 GHz at the transmitter, from which 24 carriers are modulated with polarization-multiplexed 32 quadrature amplitude modulation (PM 32-QAM) data. To enable comb regeneration at the receiver side, the two central carriers remain unmodulated. High fidelity comb regeneration is achieved by filtering the two unmodulated carriers with an approximately 25 MHz wide optical filter based on Brillouin amplification before a parametric mixer. The carriers from the regenerated comb are then used as local oscillator for SH detection. We demonstrate that all 24 carriers can be detected with an optical signal-to-noise ratio (OSNR) penalty lower than 2.5 dB in a back-to-back scenario. We also demonstrate that the whole superchannel can be transmitted through 120 km of single-mode fiber (SMF) and be detected with bit-error rate (BER) below 0.015.
|
|
| 462. |
- Lou, Fei, et al.
(författare)
-
Design and analysis of ultra-compact EO polymer modulators based on hybrid plasmonic microring resonators
- 2013
-
Ingår i: Optics Express. - 1094-4087. ; 21:17, s. 20041-20051
-
Tidskriftsartikel (refereegranskat)abstract
- Ultra-compact EO polymer modulators based on hybrid plasmonic microring resonators are proposed, simulated and analyzed. Comparing with Si slot microring modulator, hybrid plasmonic microring modulator shows about 6-times enhancement of the figure of merit when the bending radius is around 510 nm, due to its much larger intrinsic quality factor in sub-micron radius range. Influences of the EO polymer height and Si height on the device's performance are analyzed and optimal design is given. When operating with a bias of 3.6V, the proposed device has optical modulation amplitude of 0.8 and insertion loss of about 1 dB. The estimated power consumption is about 5 fJ/bit at 100 GHz.
|
|
| 463. |
- Lou, Fei, et al.
(författare)
-
Whispering gallery mode nanodisk resonator based on layered metal-dielectric waveguide
- 2014
-
Ingår i: Optics Express. - 1094-4087. ; 22:7, s. 8490-8502
-
Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a layered metal-dielectric waveguide consisting of a stack of alternating metal and dielectric films which enables an ultracompact mode confinement. The properties of whispering gallery modes supported by disk resonators based on such waveguides are investigated for achieving a large Purcell factor. We show that by stacking three layers of 10 nm thick silver with two layers of 50 nm dielectric layers (of refractive index n) in sequence, the disk radius can be as small as 61 nm similar to lambda(0) / (7n) and the mode volume is only 0.0175 (lambda(0) / (2n))(3). When operating at 40 K, the cavity's Q-factor can be similar to 670; Purcell factor can be as large as 2.3x10(4), which is more than five times larger than that achievable in a metal-dielectric-metal disk cavity in the same condition. When more dielectric layers with smaller thicknesses are used, even more compact confinement can be achieved. For example, the radius of a cavity consisting of seven dielectric-layer waveguide can be shrunk down to lambda(0) / (13.5n), corresponding to a mode volume of 0.005 lambda(0) / (2n))(3), and Purcell factor can be enhanced to 7.3x10(4) at 40 K. The influence of parameters like thicknesses of dielectric and metal films, cavity size, and number of dielectric layers is also comprehensively studied. The proposed waveguide and nanodisk cavity provide an alternative for ultracompact light confinement, and can find applications where a strong light-matter interaction is necessary.
|
|
| 464. |
|
|
| 465. |
- Lou, Xiutao, et al.
(författare)
-
Detection of elemental mercury by multimode diode laser correlation spectroscopy
- 2012
-
Ingår i: Optics Express. - 1094-4087. ; 20:5, s. 4927-4938
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a method for elemental mercury detection based on correlation spectroscopy employing UV laser radiation generated by sum-frequency mixing of two visible multimode diode lasers. Resonance matching of the multimode UV laser is achieved in a wide wavelength range and with good tolerance for various operating conditions. Large mode-hops provide an off-resonance baseline, eliminating interferences from other gas species with broadband absorption. A sensitivity of 1 mu g/m(3) is obtained for a 1-m path length and 30-s integration time. The performance of the system shows promise for mercury monitoring in industrial applications.
|
|
| 466. |
- Louis, B., et al.
(författare)
-
Fast-tracking of single emitters in large volumes with nanometer precision
- 2020
-
Ingår i: Optics Express. - : Optica Publishing Group. - 1094-4087. ; 28:19, s. 28656-28671
-
Tidskriftsartikel (refereegranskat)abstract
- Multifocal plane microscopy allows for capturing images at different focal planes simultaneously. Using a proprietary prism which splits the emitted light into paths of different lengths, images at 8 different focal depths were obtained, covering a volume of 50x50x4 mu m(3). The position of single emitters was retrieved using a phasor-based approach across the different imaging planes, with better than 10 nm precision in the axial direction. We validated the accuracy of this approach by tracking fluorescent beads in 3D to calculate water viscosity. The fast acquisition rate (>100 fps) also enabled us to follow the capturing of 0.2 mu m fluorescent beads into an optical trap. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
|
|
| 467. |
- LOUIS, BORIS, et al.
(författare)
-
Fast-tracking of single emitters in large volumes with nanometer precision
- 2020
-
Ingår i: Optics Express. - 1094-4087. ; 28:19, s. 28656-28671
-
Tidskriftsartikel (refereegranskat)abstract
- Multifocal plane microscopy allows for capturing images at different focal planes simultaneously. Using a proprietary prism which splits the emitted light into paths of different lengths, images at 8 different focal depths were obtained, covering a volume of 50x50x4 μm3. The position of single emitters was retrieved using a phasor-based approach across the different imaging planes, with better than 10 nm precision in the axial direction. We validated the accuracy of this approach by tracking fluorescent beads in 3D to calculate water viscosity. The fast acquisition rate (>100 fps) also enabled us to follow the capturing of 0.2 μm fluorescent beads into an optical trap.
|
|
| 468. |
- Lu, Chuang, et al.
(författare)
-
Robust, fast and sensitive near-infrared continuous-filtering Vernier spectrometer
- 2021
-
Ingår i: Optics Express. - : The Optical Society. - 1094-4087. ; 29:19, s. 30155-30167
-
Tidskriftsartikel (refereegranskat)abstract
- We present a new design of a robust cavity-enhanced frequency comb-based spectrometer operating under the continuous-filtering Vernier principle. The spectrometer is based on a compact femtosecond Er-doped fiber laser, a medium finesse cavity, a diffraction grating, a custom-made moving aperture, and two photodetectors. The new design removes the requirement for high-bandwidth active stabilization present in the previous implementations of the technique, and allows scan rates up to 100 Hz. We demonstrate the spectrometer performance over a wide spectral range by detecting CO2 around 1575 nm (1.7 THz bandwidth and 6 GHz resolution) and CH4 around 1650 nm (2.7 THz bandwidth and 13 GHz resolution). We achieve absorption sensitivity of 5 × 10−9 cm-1 Hz-1/2 at 1575 nm, and 1 × 10−7 cm-1 Hz-1/2 cm-1 at 1650 nm. We discuss the influence of the scanning speed above the adiabatic limit on the amplitude of the absorption signal.
|
|
| 469. |
- Lu, Chuang, et al.
(författare)
-
Time-resolved continuous-filtering Vernier spectroscopy of H2O and OH radical in a flame
- 2019
-
Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 27:21, s. 29521-29533
-
Tidskriftsartikel (refereegranskat)abstract
- We use broadband near-infrared continuous-filtering Vernier spectroscopy (CF-VS) for time-resolved detection of H2O and OH radical in a premixed CH4/air flat flame. The CF-VS spectrometer is based on a femtosecond Er:fiber laser, an external cavity that contains the flame, and a detection system comprising a rotating diffraction grating and photodetectors. Spectra of H2O and OH radical around 1570 nm are continuously recorded with 6.6 GHz spectral resolution, 4.0 x 10-7 cm-1 absorption sensitivity, and 25 ms time resolution, while the fuel-air equivalence ratio is periodically modulated with a square wave. The concentrations of the two analytes are retrieved with percent level precision by a fit of a Vernier model to each spectrum spanning 13 nm. The temporal profiles of both concentrations in each modulation cycle are repeatable and the steady-state concentration levels are in good agreement with predictions based on one-dimensional simulations of a static flat flame. The robust CF-VS spectrometer opens up for quantitative monitoring of multiple products of time-varying combustion processes with relatively simple data acquisition procedures.
|
|
| 470. |
- Lu, Guo-Wei, 1976, et al.
(författare)
-
40-Gbaud 16-QAM transmitter using tandem IQ modulators with binary driving electronic signals
- 2010
-
Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 18:22, s. 23062-23069
-
Tidskriftsartikel (refereegranskat)abstract
- We propose a novel 16-quadrature amplitude modulation (QAM) transmitter based on two cascaded IQ modulators driven by four separate binary electrical signals. The proposed 16-QAM transmitter features scalable configuration and stable performance with simple bias-control. Generation of 16-QAM signals at 40 Gbaud is experimentally demonstrated for the first time and visualized with a high speed constellation analyzer. The proposed modulator is also compared to two other schemes. We investigate the modulator bandwidth requirements and tolerance to accumulated chromatic dispersion through numerical simulations, and the minimum theoretical insertion attenuation is calculated analytically.
|
|
