Search

In this article, a highly sensitive dual-core microstructured fiber (DC-MSF) sensor is proposed. Because of the adjustable dispersion characteristic of the DC-MSF, the group refractive index (RI) difference between the ${y}$ -polarization odd and even supermodes could achieve a zero value at the dispersion turning point (DTP), which makes the DC-MSF sensor have a high sensitivity. The simulation results show that the sensitivity can be up to 52 875 nm/RIU around the RI of 1.4, the operating bandwidth of sensitivity over 104 nm/RIU is 625 nm, and the operating bandwidth of sensitivity over 105 nm/RIU is 100 nm. Moreover, the DC-MSF can also be used as a temperature sensor by coating the polydimethylsiloxane (PDMS) on the surface, and the sensitivity can be up to 23.12 nm/°C around 22 °C. The detectable RI and temperature ranges of the proposed DC-MSF sensor are 1.375–1.425 and −15 °C–95 °C, respectively.

Large‐scale autostereoscopic three‐dimensional (3D) displays can give audiences a truly immersive feeling with strong visual impact. However, the traditional autostereoscopic 3D display systems are limited by the display hardware, making it difficult to directly achieve large‐scale 3D displays with high resolution. Multiscreen splicing with laser backlights can be used for large‐scale and ultrahigh‐resolution 3D display, but it normally results in subscreen image asynchronization, view zone error, or obvious edge overlapping. To solve the problems mentioned above, a distributed real‐time rendering system for ultrahigh‐resolution multiscreen 3D display is proposed. Fifteen 3D LCD display devices are driven through a host, cooperating with laser backlights, a lenticular lens array (LLA), and a directional diffuser to display high resolution, high frame rate, large size, and wide‐viewing angle 3D images. The resolution of the whole display system can reach 23,040 × 21,600. The rendering system provides a large‐scale and real‐time 3D scene image with an ultrahigh‐definition resolution at a speed of 40 frames per second and high quality. We designed a distributed real‐time rendering system for ultrahigh‐resolution multiscreen 3D display. The rendering system provides a large‐scale and real‐time 3D scene image with an ultrahigh‐definition resolution at a speed of 40 frames per second with high quality. The system can realize real‐time high‐definition natural‐transition true 3D image cooperated with large‐scale autostereoscopic displays hardware system.

In this paper, a simple structure dual-core photonic crystal fiber (SS-DC-PCF) polarization beam splitter (PBS) based on the surface plasmon resonance (SPR) effect and symmetric dual-core coupling mode theory is proposed. For the proposed SS-DC-PCF-1 PBS, the coupling lengths (CLs) and coupling length ratio (CLR) are analyzed, and the variations of the normalized output powers with the propagation length are investigated for the chosen wavelengths 1.434, 1.451, and 1.469 µm. The extinction ratio in cores A and B are compared at the three splitting lengths (SLs) 170, 173, and 176 µm. When the optimal SL is 176 µm, the splitting bandwidth (SB) is 255 nm (1.437–1.692 µm), and the insertion loss (IL) is less than 0.043 dB. The regulations of the CLs and CLR with the change of the structure parameters are analyzed. For the proposed SS-DC-PCF-2 PBS, the optimal SL is 232 µm, the SB is 201 nm (1.249–1.450 µm), and the IL is less than 0.042 dB. Finally, it is demonstrated that the total SB of the proposed SS-DC-PCF-1 PBS and SS-DC-PCF-2 PBS is 443 nm (1.249–1.692 µm), which can cover the O+E+S+C+L+U band, even if the gold film thickness changes by ±1nm. The proposed SS-DC-PCF PBS has excellent performances, such as ultrashort SL, ultrawide SB, ultralow IL, and good error-tolerance rate. It will have important applications in all-fiber optical systems.

In this paper, a reverse-strip AlGaAs waveguide with three zero-dispersion wavelengths (ZDWs) is designed. The corresponding three ZDWs are located at 3.74, 6.56, and 8.89 µm. The nonlinearity coefficient of the proposed reverse-strip AlGaAs waveguide is calculated as 2.09W^−1m^−1 at wavelength 4.9 µm. The effects of pump pulse parameters, waveguide length, and noise coefficient on the nonlinear dynamics of supercontinuum (SC) generation are investigated. When the hyperbolic secant pump pulse with a wavelength of 4.9 µm, peak power of 900 W, and duration of 100 fs is launched into the proposed waveguide and propagated after a 3 mm length, highly coherent and multi-octave mid-infrared (MIR) SC spanning from 2.2 to 14.5 µm (more than 2.7 octaves, at −40dB level) is generated. Finally, a possible fabrication process of the reverse-strip AlGaAs waveguide is introduced. Our research results have important applications in MIR photonics, MIR spectroscopy, optical precision measurement, and more.

In this paper, we numerically investigate the mid-infrared supercontinuum (SC) generation in a suspended ${{\rm As}_2}{{\rm Se}_3}$As_2Se_3 ridge waveguide, which is designed with the two zero-dispersion wavelengths. Simulation results show that when the pump pulses at wavelength 3.3 µm with width of 100 fs and peak power of 900 W are launched into the anomalous dispersion region of the designed waveguide with a length of 0.87 mm, the SC can be generated in the wavelength range from 1.76 to 14.42 µm (more than three octaves), extending deep into the “fingerprint” region. The stability of the generated SC is confirmed by the first-order coherence. Moreover, we demonstrate the performance of the SC-based frequency comb by assuming a 50 pulse pump source at a repetition rate of 100 MHz.

In this paper, we design a polarization-maintaining CS_2-core photonic crystal fiber (PM-CCPCF). The two air holes in the x direction are infiltrated with C_2H_5OH in order to introduce birefringence. By optimizing the structure parameters of the PM-CCPCF, it is demonstrated that the x-polarization fundamental mode has an all-normal dispersion profile and the corresponding y-polarization fundamental mode has an anomalous dispersion profile for a pump wavelength of 1.76 μm. Then, we investigate the supercontinuum (SC) generations when different fiber lengths, pump peak powers, and pump pulse widths are chosen, respectively. Simulation results show that for the x-polarization and y-polarization fundamental modes, highly coherent SCs can be generated by appropriately choosing the fiber length and pump pulse parameters. Finally, nonlinear propagation dynamics are analysed when the optimized fiber length and pump pulse parameters are used. The bandwidth of the SCs generated for the x-polarization and y-polarization fundamental modes can be up to 0.82 and 1.26 octave, respectively.

In this Letter, we demonstrate experimentally for the first time, to the best of our knowledge, discrete ultraviolet (UV) wavelength generation by cascaded intermodal FWM when femtosecond pump pulses at 800 nm are launched into the deeply normal dispersion region of the fundamental guided mode of a multimode photonic crystal fiber (MPCF). For pump pulses at average input powers of P_av=450, 550, and 650 mW, the first anti-Stokes waves are generated at the visible wavelength of 538.1 nm through intermodal phase matching between the fundamental and second-order guided mode of the MPCF. The first anti-Stokes waves generated then serve as the secondary pump for the next intermodal FWM process. The second anti-Stokes waves in the form of the third-order guided mode are generated at the UV wavelength of 375.8 nm. The maximum output power is above 10 mW for P_av=650  mW. We also confirm that the influences of fiber bending and intermodal walk-offs on the cascaded intermodal FWM-based frequency conversion process are negligible.

In this Letter, polarization-dependent intermodal four-wave mixing (FWM) is demonstrated experimentally in a birefringent multimode photonic crystal fiber (BM-PCF) designed and fabricated in-house. Femtosecond pump pulses at wavelengths ∼800  nm polarized along one of the principal axes of the BM-PCF are coupled into a normal dispersion region away from the zero-dispersion wavelengths of the fundamental guided mode of the BM-PCF. Anti-Stokes and Stokes waves are generated in the 2nd guided mode at visible and near-infrared wavelengths, respectively. For pump pulses at an average input power of 500 mW polarized along the slow axis, the conversion efficiencies η_as and η_s of the anti-Stokes and Stokes waves generated at wavelengths 579.7 and 1290.4 nm are 19% and 14%, respectively. For pump pulses polarized along the fast axis, the corresponding η_as and η_s at 530.4 and 1627 nm are 23% and 18%, respectively. We also observed that fiber bending and intermodal walk-off have a small effect on the polarization-dependent intermodal FWM-based frequency conversion process.

We propose and design a photonic-integrated optical biochemical sensor, which comprises a microring resonator and angular gratings in a silicon-on-insulator waveguide. With the combination of the angular gratings, the measurement range of the angular grating-microring resonator-based sensor significantly increases without the restriction of a free spectral range. Optimization of the several key structural parameters is investigated to achieve favorable transmission properties. A high-quality factor of more than 1.03×10^5 can meet the requirements of high sensitivity and low detection limit. The simulation results on the biochemical bulk sensing show that a concentration sensitivity of more than 95.27 pm/% and detection limit of less than 0.329% can be obtained. A large measurement range of 50.2 nm is achieved by the combination of the angular gratings. The investigation on the combination of microring resonator and angular grating is a valuable exploration of the liquid and gas biomedical sensing for the ultra-large measurement range.

Generation of spectrally-isolated wavelengths in the violet to blue region based on cascaded degenerate four-wave mixing (FWM) is experimentally demonstrated for the first time in a tailor-made photonic crystal fiber, which has two adjacent zero dispersion wavelengths (ZDWs) at 696 and 852 nm in the fundamental mode. The influences of the wavelength λ_p and the input average power P_av of the femtosecond pump pulses on the phase-matched frequency conversion process are studied. When femtosecond pump pulses at λ_p of 880, 870, and 860 nm and P_av of 500 mW are coupled into the normal dispersion region close to the second ZDW, the first anti-Stokes waves generated near the first ZDW act as a secondary pump for the next FWM process. The conversion efficiency η_as2 of the second anti-Stokes waves, which are generated at the violet to blue wavelengths of 430, 456, and 472 nm, are 4.8, 6.48, and 9.66%, for λ_p equalling 880, 870, and 860 nm, respectively.

We demonstrate experimentally an enhanced intermodal four-wave mixing (FWM) process through coupling positively chirped femtosecond pulses into the deeply normal dispersion region of the fundamental mode of an in-house fabricated photonic crystal fiber (PCF). In the intermodal phase-matching scheme, the energy of the pump waves at 800 nm in the fundamental mode is efficiently converted into the anti-Stokes waves around 553 nm and the Stokes waves within the wavelength range of 1445–1586 nm in the second-order mode. The maximum conversion efficiency of η_as and η_s of anti-Stokes and Stokes waves can be up to 21% and 16%, respectively. The Stokes frequency shift Ω is 5580  cm^−1. The fiber bending and intermodal walk-off effect of pulses do not have significant influence on the nonlinear optical process.

Based on degenerate four-wave mixing (FWM), the broadband Stokes waves are efficiently generated at the mid-infrared wavelength above 2 μm, for the first time to our knowledge, by coupling the femtosecond pulses into the fundamental mode of a silica photonic crystal fiber designed and fabricated in our laboratory. Influences of the power and wavelength of pump pulses on the phase-matched frequency conversion process are discussed. When pump pulses with central wavelength of 815 nm and average power of 300 mW are used, the output power ratio of the Stokes wave generated at 2226 nm and the residual pump wave P_s/P_res is estimated to be 10.8∶1, and the corresponding conversion efficiency η_s and bandwidth B_s of the Stokes wave can be up to 26% and 33 nm, respectively. The efficient and broadband Stokes waves can be used as the ultrashort pulse sources for mid-infrared photonics and spectroscopy.

Reconstruction the computer generated Fresnel hologram of complex 3D object based on compressive sensing (CS) is presented. The hologram is synthesized from a color image and the depth map of the 3D object. With the depth map, the intensity of the color image can be divided into multiple slices, which satisfy the condition of the sparsity of CS. Thus, the hologram can be reconstructed at different distances with corresponding scene focused using the CS method. The quality of the recovered images can be greatly improved compared with that from the back-propagation method. What's more, with the sub-sampled hologram, the image can be ideally reconstructed by the CS method, which can reduce the data-rate for transmission or storage.