Traditional transmission wavefront detection methods cannot accurately characterize complex wavefront features in broad-spectrum applications. To address this, a high-precision wavefront reconstruction method that combines wavefront discretization with a modified Conrady formula (MCF) is proposed. The wavefront is discretized by modeling a nonlinear relationship between optical path difference (OPD) and wavelength at each sampling point. These per-point models are then solved using the MCF, overcoming the limitations of Zernike polynomial fitting in capturing high-frequency details and localized features. In an experiment, the transmission wavefront of a lens at an operating wavelength of 632.8 nm was measured. The relative error of the peak-to-valley (PV) value between the reconstructed and measured wavefronts was 1.29%, and the root-mean-square (RMS) value of the residual wavefront was 2.276 nm, confirming the feasibility and effectiveness of the method.
Tilted fiber Bragg grating (TFBG)-based surface plasmon resonance (SPR) sensors have attracted considerable attention for optical fiber biochemical sensing owing to their compact structure and strong cladding-mode interaction. However, the limited biomolecule immobilization efficiency on metal surfaces often restricts sensing performance. In this work, a TFBG-SPR biosensor functionalized with a polydopamine-graphene oxide (PDA-GO) composite layer is proposed for rapid and label-free detection of human immunoglobulin G (IgG). A femtosecond laser-inscribed TFBG coated with a thin gold film is employed to excite SPR, while the PDA-GO layer provides a stable biofunctional interface for biomolecule interaction on the sensing surface. An intensity-based interrogation scheme is implemented by monitoring the intensity variation of a selected cladding mode within the SPR attenuation band. Experimental results demonstrate a clear concentration-dependent response to IgG within the tested range of 20-60 & micro;g & centerdot;mL-1, with an exponential fitting coefficient of R2 = 0.997 and an average intensity sensitivity of 0.0475 dB (& micro;g & centerdot;mL-1)-1. The sensing signal reaches equilibrium within approximately 1 min, indicating rapid detection capability. The proposed PDA-GO-functionalized TFBG-SPR sensor provides a compact and effective platform for label-free biochemical detection and shows promising potential for optical fiber biosensing applications.
Large-aperture temporal imaging in four-wave mixing (FWM) time lenses is limited by pump-induced deviation from the ideal quadratic phase. Strong stretching of the pulsed pump before nonlinear interaction usually requires a high peak power, which leads to Kerr phase accumulation during dispersive propagation and shifts the imaging condition. A dualpump nondegenerate FWM time lens is adopted to suppress this distortion by reducing the peak-power requirement on the chirped pump through a continuous-wave auxiliary pump. A conversion bandwidth of up to 170 nm is achieved, and the temporal response remains closer to the ideal quadratic limit. This scheme provides an effective route to large-aperture temporal imaging.
The power balance performance of laser pulses at the target chamber is essential for symmetric compression in inertial confinement fusion (ICF) experiments. With the increasing demand for experimental precision, laser facilities worldwide continuously seek to enhance laser power balance, particularly through precise manipulation of pulse waveforms. This study presents the challenges encountered in advancing pulse precision regulation under operational conditions at a high-power laser facility. Corresponding techniques have been implemented in the final optical assembly, the main amplifier section, and the injection system. Moreover, data-driven intelligent parameter control methods were adopted, resulting in significant advances. Finally, breakthroughs were achieved in precision pulse waveform control, enabling laser parameters to fully satisfy the requirements of high-value physics experiments.
Fused silica is an indispensable optical substrate for modern photonics, featuring excellent transmittance, high stability, and superior complementary metal-oxide-semiconductor (CMOS) compatibility, but its weak intrinsic nonlinearity limits applications in wavelength-dependent nonlinear regulation and ultrafast photonic switching. Here, Ag/Y sequential ion implantation is employed to incorporate Ag nanoparticles (Ag NPs) and Y dopants into silica. Inhomogeneous Y doping modulates the local dielectric environment around the nanoparticles and induces a resonance redshift, enabling tunable nonlinear optical properties. The ion-implantation-broadened absorption spectrum also enables a distinct nonlinear response at 1030 nm. This study opens a promising route for developing high-performance ultrafast photonic devices.
