Abstract Photoacoustic imaging, especially for intravascular and endoscopic applications, requires ultrasound probes with miniature size high sensitivity. In this paper, we present a new photoacoustic sensor based on small-sized fiber laser. Incident waves exert pressures the optical laser induce harmonic vibrations of fiber, which is detected by frequency shift beating signal between two orthogonal polarization modes in This presents noise-equivalent pressure 40 Pa over 50-MHz bandwidth. We...

A miniature fiber-optic Fabry-Perot is built on the tip of a single mode fiber with thin silk fibroin film as diaphragm for pressure measurement. The regenerated from aqueous solution obtained by an environmentally benign fabrication process, which exhibits excellent optical and physicochemical properties, such transparency in visible near infrared region, membrane-forming ability, good adhesion, high mechanical strength. resulted sensor therefore highly biocompatible shows airtightness...

We demonstrate a stable and linear photonic radio frequency (RF) phase shifter based on differential-group-delay element the polarization sensitive effect of an optical modulator. The shift can be tuned continuously over 360 degrees for RF signals 40GHz with electrical control voltage from -7.5 to +7.5V.

The trade-off between lateral resolution and depth of focus (DOF) severely limits the capability endoscopic optical coherence tomography (OCT) for high-resolution deep-tissue imaging. To address this issue, we developed a novel miniature all-fiber axicon OCT probe by inserting segment gradient-index (GRIN) fiber piece single-mode (SMF) an polished from no-core fiber. GRIN lens served as beam expander extending DOF 5.2 times while maintaining high 2 μm. extension was experimentally verified...

In this paper, we demonstrate that the sensitivity of Faraday effect based heterodyning fiber laser sensors for magnetic field can be effectively enhanced by lowering intrinsic linear birefringence inside cavity. Well explained theoretical analysis and confirmed tuning through transversal force, it shows to intensity is inversely proportional birefringence. A CO(2)-laser treatment therefore proposed tune intra-cavity With treatment, lowered permanently enhance a sensor field.

We have developed highly sensitive photonic ultrasound hydrophones based on polymer-packaged dual-polarization-mode fiber lasers. The incident wave is scattered by the polymer cylinder due to difference in elastic property. can drive harmonic vibration of and result optical response terms beat-frequency variation laser output. Experimental results exhibit a broadband at frequencies below 1 MHz. individual modes are excited waves with different efficiencies, yielding frequency-dependent...

Optoacoustic vibrations in optical fibres have enabled spatially resolved sensing, but the weak electrostrictive force hinders their application. Here, we introduce photothermally induced acoustic (PTAVs) to realize high-performance fibre-based optoacoustic sensing. Strong with a wide range of axial wavenumbers kz are actuated by using focused pulsed laser. The local transverse resonant frequency and loss coefficient can be optically measured an intra-core sensor via spectral analysis....

A magnetic field sensor is proposed by placing a dual-polarization fiber grating laser under copper wire. With perpendicular applied, an electrical current flowing through the wire can generate Ampere force to squeeze laser, resulting in birefringence change inside cavity and hence of beat note frequency. When alternating injected into wire, induced frequency be discriminated from environment disturbances. novel fiber-optic therefore demonstrated with high sensitivity inherent immunity

A new exact analytical model is presented to analyze the dispersive transmission in microwave fiber-optic links using a dual-drive Mach-Zehnder external modulator (DD-MZM). The very general and can be applied almost all operating conditions of DD-MZM, such as bias point, drive level, phase shift, modulation index difference between DD-MZM drives. results simple closed-form expressions for output power spectrum, permitting an accurate fast analysis links. Expressions two special cases, double...

In this paper, we theoretically and experimentally demonstrated the residual chromatic dispersion (CD) monitoring of 100-Gbit/s carrier suppress return-to-zero differential quadrature phase shift keying (CS-RZ DQPSK) signals by evaluating asymmetry ratio delay tap asynchronous sampling. This scheme can easily differentiate positive negative CD fiber link. The resolution is better than 8 ps/nm measurable range around +/- 24 for 100 Gbit/s CS-RZ DQPSK signals. We also simultaneously realize...

In this paper, we demonstrated a signed chromatic dispersion (CD) monitoring method of 10 GHz nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) and return-to-zero (RZ-DPSK) signals by using asynchronous delay-tap sampling an imperfect tuned delay interferometer. This could monitor not only the value but also polarity residual CD. The demodulated show amplitude shoulders on rising edge or trailing with CD accumulation. Delay-tap scatter plots reflect signal distortion unique...

Microwave signals can be generated by beating the two orthogonal polarization modes from a dual-frequency fiber grating laser. In this paper, we present that phase noise of microwave signal significantly reduced via optical feedback cascading an external cavity. This is achieved as result bandwidth narrowing each laser mode when introducing phase-matched feedbacks into By optimizing cavity length and ratio, level over low frequencies has been up to 30 dB, -42 -72 dBc/Hz at 1 kHz, -102 10...

Fiber lasers have been exploited as sensors for the detection of extremely weak mechanical parameters, by monitoring radio-frequency beat signal between orthogonal polarized lasing modes. This sensor scheme has presented advantages including advanced measurement capability, low cost and convenience in demodulation, resistance to environmental disturbances, intrinsic multiplexing capability. Here, we demonstrate capability fiber laser low-frequency (<;2 kHz) acoustic waves ultrasound signals...

We investigate the effects of polarization-mode dispersion (PMD) and chirp on radio-frequency tone-based chromatic (CD) monitoring method, show that PMD induce significant CD errors. propose a technique to suppress these effects. Experiment results errors induced by fluctuation are greatly suppressed.

We propose and experimentally demonstrate a chromatic dispersion (CD)-insensitive first-order polarization mode (PMD) monitoring method based on radio-frequency (RF) power measurement.In high-speed (>10-GSym/s) transmission systems, narrowband fiber Bragg grating (FBG) notch filter filters out the optical components at 10GHz away from carrier.After square-law detection, 10-GHz RF tone changes with PMD is insensitive to CD, which can be used as signal.Compared techniques utilizing clock tone,...

A simple technique has been proposed and demonstrated to generate radio-frequency (RF) signal based on a fiber grating laser with multi-octave tunablity. The is fabricated by inscribing wavelength-matched Bragg pair in short section of low-birefringence Er/Yb co-doped fiber. RF can be obtained beating the two-polarization mode output its frequency determined birefringence within cavity. By slicing cavity into two sections then aligning them rotated angle, beat continuously tuned range as...

In this paper, dual-polarization fiber grating lasers are exploited as heterodyning sensors for hydrostatic pressure measurement. The laser is formed by photo-inscribing two highly reflective wavelength-matched Bragg gratings over a short section of Er-doped fiber. measurement carried out monitoring the beat frequency between orthogonally polarized output. sensitivity bare sensor -0.59 MHz/MPa. Theoretical analysis suggests that response dominantly determined change in intra-cavity...

All-optical ultrasound manipulates waves based on laser and photonics technologies, providing an alternative approach for pulse-echo imaging. However, its endoscopic imaging capability is limited ex vivo by the multifiber connection between probe console. Here, we report all-optical in using a rotational-scanning that relies small sensor to detect echo waves. The acoustically induced lasing frequency change measured via heterodyne detection beating two orthogonally polarized modes, enabling...

For lightwave transmission systems employing advanced modulation formats such as phase-shift keying (PSK) and quadrature-amplitude (QAM), chromatic dispersion monitoring based on average variance of optical power has been demonstrated. Theoretical analyses are verified by simulations, experiment results show that the at receiver is a simple effective statistical parameter to monitor residual link.

A refractive index sensor by Brillouin scattering in a micro fiber with diameter of 2 μm is experimentally demonstrated. peaks introduced interaction between the fundamental optical mode and axially symmetric radial acoustic modes are identified. We find axial frequency linearly proportional to sodium chloride solution around 1.33. sensitivity approximately 1.6 GHz/RIU achieved. It proposes that candidate for measurement.

In this paper, the spatial sensitivity of a dual-polarization fiber grating laser sensor is characterized by measuring response in terms beat-frequency change to localized transverse loading at different longitudinal positions. The induced frequency shift proportional local birefringence and normalized light intensity, as result resonant nature cavity. Measured suggests that profile mainly determined cavity length, well reflectivities gain. We found higher mass (or force) can be obtained...

A new exact analytical model is presented to analyze the dispersive transmission in subcarrier multiplexing (SCM) fiber-optic links using dual-drive Mach-Zehnder external modulator (DD-MZM). The very general and can be applied almost all operating conditions of DD-MZM, such as bias point, drive level, phase shift, modulation index difference between DD-MZM drives. results simple, new, closed-form expressions for output power spectrum, permitting an accurate fast analysis links. Two special...