We report a compact all-optical side-firing probe directly ablated on a mode-expanded hybrid fiber end using a high-precision femtosecond laser processing technique. A segment of coreless silica fiber was adopted to achieve a large beam size and manipulation of the far field divergence angle. The radiating beam properties of the side-firing tip have been experimentally investigated and compared with numerical simulations.
We propose a novel scheme to reduce the sensitivity to pump power variation in optical fiber anemometers that used fiber Bragg grating (FBG) inscribed in light absorption optical fibers. By modulating the output power of the pump laser and by measuring the time constant of the wavelength change of the FBG sensor, we theoretically and experimentally demonstrated that significant reduction of the sensitivity of flow measurement to pump power can be achieved.
A novel hot-wire anemometer based on a silver-coated optical fiber Bragg grating (FBG) is proposed and experimentally demonstrated with the assistance of a short length of no-core fiber (NCF). The silver coating deposited on the surface of the FBG absorbs light of a pump laser, which is coupled into the fiber cladding by the NCF, to generate the heat, whereas air flow cools down the FBG by taking the heat away. A dynamic thermal equilibrium with a temperature codetermined by the pump laser power and airflow velocity can be reached. Bragg wavelength of the FBG changes with temperature thus is used to measure airflow velocity. Experimental results reveal that the highest resolution of
We propose and demonstrate a tunable wavelength converter for optical packets with a 40 Gb/s non-return-to-zero differential phase shift keying payload and an in-band 1.25-Gb/s on-off keying label. To achieve wide wavelength coverage and integrability, we use a dual pump scheme exploiting four-wave mixing in semiconductor amplifiers. For flexibility and scalability, in-band labels are used. For phase stability, we use a quantum-dash mode-locked laser as a multi-wavelength source for the dual pumps with tunability provided by the output filter. The bit error rate (BER) performance is evaluated for both payload and label after wavelength conversion. We report error free conversion
Effects of the prestrained growth of a low-In InGaN/GaN quantum well (QW) before the designated light-emitting high-In InGaN/GaN multi quantum wells (MQWs) in GaN-based laser diodes (LDs) are numerically investigated. Simulation results show that the inserted low-In InGaN/GaN QW does not remarkably change the absorption loss, and the ratio of recombination current of low-In InGaN/GaN QW over injection current is very small, especially after LD is lasing. However, it weakens the polarization fields, resulting in less tilted energy bands, and the overlap of electron–hole pairs is greatly increased, which reduces threshold carrier concentrations of MQWs, leakage current, and nonradiative recombination. The performance of LD is enhanced. Threshold current is reduced by 19%, and output power is increased by 59% at the injection current of 120 mA.
A monolithic semiconductor ring laser is operated as an all-optical set-reset flip-flop triggered by external optical pulses. Bit-error-rate measurements of set-reset switchings under the injection of a pseudo-random-bit-sequence have been performed, showing reliable operation up to 10 Gb/s.
A compact transmitter optical sub-assembly (TOSA) has been developed for a 100 Gb/s Ethernet system with a long transmission distance of 40 km over single-mode fiber. The TOSA consists of electro-absorption modulator integrated distributed feedback laser diode arrays and a polarization beam combiner for wavelength multiplexing to obtain a high optical output power and a high dynamic extinction ratio. We confirmed that the TOSA successfully achieved an error-free four-lane
A passively mode-locked fiber ring laser only based on one section of D-shaped fiber is proposed, where the nonlinear polarization rotation mechanism arises without polarizer or wave plate. By increasing the pump power, mode locking is self-started, a laser pulse with a repetition rate of 6.04 MHz is generated, and its evolutions of temporal, spectral, and polarization properties under different pump powers are discussed.
The aim of this letter is to address the barrier imposed by the exponential-time complexity of current large-signal theory for calculating the chirp-induced distortions in short-range optical transmission systems using directly modulated lasers. This is a critical issue for modern optical orthogonal frequency division multiplexing signals with hundreds of subcarriers, especially for digital signal processing techniques intended to mitigate transmission impairments. A polynomial-time complexity model is proposed and its accuracy can be increased by including higher-order intermodulation products (IMPs). Signal-to-interference ratio differences between our analytical model and simulation results
An optoelectronic electromagnetic generator was developed for the creation and shaping of picosecond pulses. The system integrated a homemade compact picosecond source. The infrared pulse-source switches optoelectronic components mounted on a microstrip line generator. The technology is based on a microchip laser that delivers subnanosecond pulses, whose duration is shortened in a standard optical fiber before amplification in a 3D multipass amplifier. This technique permits the generation of picosecond optical pulses with several tens of microjoules and kilohertz repetition rates. Rectangular electrical picosecond pulses with kilovolt positive and negative amplitudes are obtained with particular shapes and bipolar electrical pulses.