An open-cavity optical fiber gas pressure sensor based on the Vernier effect is proposed. The sensor consists of two Fabry-Perot interferometers (FPIs) connected in parallel. As a sensing FPI, FPI-1 is an open-cavity FPI and composed of single-mode fiber (SMF), hollow core capillary (HCC), and twin-hole and dual-core fiber (THDCF). The open-cavity FPI structure is constructed using the air holes of THDCF. FPI-2 consists of SMF and HCC with a large inner diameter and works as a reference FPI. The manufacturing cost of the sensor is low and easy to manufacture. This study explored the relationship between the magnification factor and the cavity lengths of the sensing FPI and the referencing FPI. After optimizing, the sensor has a sensitivity of -168.82 nm/MPa in the gas pressure range of 0.1-1.6 MPa, which is 48.37 times the sensing sensitivity of single FPI. In addition, the temperature crosstalk of the sensor is 2.285 x 10(-4) MPa/degrees C. Repeated experiments have demonstrated that the sensor has good repeatability and stability. Therefore, the proposed sensor structure provides a new idea for the design and application of optical fiber gas pressure sensors with ultrahigh sensitivity and lower temperature cross sensitivity.

A novel method to fabricate microchannels into fused silica capillaries and hollow fibres by a high-voltage high-frequency corona discharge induced by a Tesla coil is demonstrated. Channels as narrow as 2.2 m are successfully made in capillaries with 2 m inner and 125 mu m outer diameters.

In this paper, we present a tailored multiwavelength Yb-fiber laser source in the 1.03 μm spectral region for spatially multiplexed digital holographic acquisitions. The wavelengths with bandwidths below 0.1 nm were spectrally separated by approximately 1 nm by employing fiber Bragg gratings for spectral control. As a proof of concept, the shape of a cylindrically shaped object with a diameter of 48 mm was measured. The holographic acquisition was performed in single-shot dual-wavelength mode with a synthetic wavelength of 1.1 mm, and the accuracy was estimated to be 3% of the synthetic wavelength.

A tunable single-wavelength Erbium-doped all-fiber laser was experimentally demonstrated. The tuning is obtained with a stress-optic phase modulator based on a twin-hole fiber and a chirped fiber Bragg grating in a medium birefringence fiber. 

Tm-doped pulsed fiber lasers are attractive for a number of applications in spectroscopy owing to their potential tunability, extension of the spectral band for optical communications and for pumping of mid-infrared nonlinear optical devices. Moreover, Tm-doped fiber (TDF) lasers and amplifiers can be pumped with readily available diode or Er-doped fiber lasers. Figure-8 (F8) lasers containing nonlinear amplifying loop mirror (NALM) [1] were among the first passively mode-locked ultrashort-pulsed lasers where subpicosecond pulse generation has been demonstrated using Er-doped gain fibers [2]. The geometry is attractive due to the fact that the laser is, ideally, an inherently pulsed system if a balanced 3 dB coupler is employed in the Sagnac loop (see Fig.1(a)). The F8 cavity configuration is therefore attractive for demonstrating passive mode-locking in 2 μm range where low-loss fiber components and saturable absorber mirrors are still under active development. F8 cavities are well known for their rich dynamics where targeting a specific operational mode can be far from trivial. For instance, F8 cavities with TDF have been shown to operate in fundamental soliton, multiple-pulse, noise-like long pulse regimes [3,4].

A compact three‐wavelength narrow‐linewidth fiber laser with single pump is demonstrated. The multiple‐wavelength output signal can be effectively employed to synthesize large effective probing wavelength of up to 1.16mm for high depth resolution digital holography.

Dynamic frequency tuning of trapped light in a phase-shifted fiber grating cavity is demonstrated by high-voltage electrical pulses. Y-polarization light is found to be sensitive to refractive index changes caused by a transverse pressure-wave.

Dynamic wavelength switching of a phase-shifted fiber grating cavity with electrical pulses is studied experimentally and numerically. Simulations accurately describe observations. The effect of acoustic oscillations and fiber Bragg grating cavity refilling explains the results.