Wavelength and power stabilization of a three wavelength erbium doped fiber laser using a Nonlinear Optical Loop Mirror

Abstract: This paper describes the use of a Nonlinear Loop Mirror to achieve wavelength and power stabilization in a three wavelength Erbium doped fiber ring laser. The laser uses three fiber Bragg grating reflectors as the oscillation wavelength selecting filters. The influence of the length of the Nonlinear Loop Mirror (NOLM) on the laser stability both in terms of wavelength and laser output power was investigated. The laser performance was improved by changing the length of the Loop Mirror to an optimal length and three simultaneous wavelength oscillations with acceptable power and wavelength stability were achieved

A dual wavelength erbium doped fibre ring laser employing 3dB coupler and FBGs in preparation for dispersion measurement

Abstract: A simple dual -wavelength c-band laser source with the aid of Fibre Bragg gratings (FBG) with an optical SNR of up to 70dB is demonstrated. The laser includes a 3,2m Erbium doped fibre with 11,38dB/m absorption in a ring resonating cavity with optical couplers. The ring cavity had two FBGs centred at 1555.12nm and 1560.32nm attached by a 3dB coupler. A 1m long sagnac loop with 70:30 coupling was used to stabilise the dual wavelength emission to about 2dB. The multiwavelength and narrow spectral width of 0.183nm and 0.195nm of the laser can be used for dispersion measurement in WDM communication links which consist of more than one wavelength. The laser was characterised for dual output power response and power stability. The paper present a characterisation of an Erbium doped fibre (EDF) ring laser. The laser is cost effective and dynamic in selecting preferred components for optimal performance in terms of power and wavelength stability, wavelength selectivity and narrow spectral width. EDF lasers are commercial available and already showing great promise in terms of the formidability and compatibility with current industrial requirements

Wavelength-tunable passively mode-locked Erbium-doped fiber laser based on carbon nanotube and a 45° tilted fiber grating

A wavelength-tunable all-fiber Erbium-doped mode-locked fiber laser based on carbon nanotubes and 45° tilted fiber grating (TFG) is demonstrated. We investigated the effect of PDL of 45TFG in the tuning range of a mode locked laser. The central wavelength of the laser can be tuned continuously from 1559.85 nm to 1564.46 nm with a tuning range of 4.6 nm using a weak 45TFG and from 1553.37 nm to 1568.63 nm with a tuning range of 15.26 nm using a strong 45TFG. The laser maintains high signal to noise ratio >50 dB across all the wavelength tuning range

Tunable Multiwavelength SOA-Based Fiber Laser

Tunable multiwavelength fiber lasers based on semiconductor optical amplifiers (SOA) have received attracting interest due to their wide prospective applications in dense division multiplexing (DWDM) systems and optical sensing. Using an SOA in a nonlinear optical loop mirror (NOLM), we demonstrate up to 13 lasing peaks by controlling the pump current and the polarization controller. At maximum pump current (450 mA), the emitted multiwavelength is between 1550 nm and 1572 nm with a wavelength spacing of 1.87 nm and 3 dB output linewidth of 0.8 nm with an output power of −7 dBm and 27 dB optical signal-to-noise ratio (OSNR). The multiwavelength output power and multiwavelength peak stability are investigated, and it was found that the power fluctuation of each multiwavelength line is less than 0.2 dB. In addition, by adjusting the polarization controllers (PCs) and SOA temperature, we obtained a tunable multiwavelength emission. The proposed fiber laser offers advantages such as simple structure, low loss, and long-time stable and multiwavelength emission

Tunable Single-, Dual- and Multi-wavelength Fibre Lasers by Using Twin Core Fibre-based Filters

Tunable fibre lasers draw intensive attention because their emission wavelength can be systematically tuned within a certain spectral range, which allows using a single laser source instead of several sources. This is convenient and cost-effective for many applications in a range of fields, such as telecom, material processing, microscopy, medicine and imaging and so on. The laser wavelength can be tuned in a certain range of wavelength by inserting wavelength-selective elements into the laser’s optical cavity. This chapter describes the twin core fibre (TCF)-based filters, which work as the wavelength-selective element. They are introduced into the ring cavity to implement tunable single-, dual- and multi-wavelength fibre lasers. First, we deduced the coupled-mode theory of TCF-based filter. Second, we experimentally and numerically characterized the optical properties of TCF-based filters including free spectral range, polarization dependence, strain effect and bending effect. Finally, we investigated three tunable fibre lasers which operate at single-, dual- and multi-wavelengths, respectively. The operation mechanism of the fibre lasers mainly involved the elastic-optic effect, polarization hole burning effect and non-linear optical loop mirror. We emphasized the tuning mechanism and the tuning characteristics of the tunable fibre lasers

Multiwavelength fiber laser based on different types of semiconductor optical amplifiers

Communication system in optical fiber technology has emerged as a demanding field especially for the new dense wavelength-division multiplexed (DWDM) system wherein many functional applications and basic laser system are included. The generation of multiple laser lines in multiwavelength fiber laser (MWFL) is significant in semiconductor optical amplifier (SOA) device utilization as a medium of gain to achieve a flat laser spectrum. Apart from Erbium-doped fiber amplifier (EDFA) and Raman amplification that have high mode competition and high pumping power respectively, MWFL configuration has delegated SOA due to its special inhomogeneous characteristic as a device of stability compared to other devices of scattering and amplification effects. An investigation on the types of different wideband travelling wave (TW) SOA with parameters such as optical gain, output power, noise figure (NF) and amplified spontaneous emission (ASE) noise and bias current was carried out through OptiSystem and MATLAB software and then verified by benchtop experiments. Linear SOA had the most flat gain with low NF and ASE pattern at input power -30 dBm compared with nonlinear SOA. A practical Lyot-combed and fiber Bragg grating (FBG) were constructed using unidirectional single cavity in different types of SOA and linear SOA displayed the flattest peak powers. Multiwavelength spectrum from linear, nonlinear SOA and booster optical amplifier (BOA) were varied by intensity, polarization angle (PA), in-line polarizer and time stability by applying performance evaluator such as the number of laser lines, extinction ratio (ER), channel spacing and highest optical power. The laser experiment for linear SOA concluded with the flattest spectrum in time stability which was true to the characterization modelling result and it also acted differently as nonlinear SOA and BOA that vary greatly to nonlinearity with different PA

Robust mode-locking in a hybrid ultrafast laser based on nonlinear multimodal interference

We experimentally demonstrate the realization of a half-polarization-maintaining (half-PM) fiber laser, in which mode-locking is provided by a reflective multimode-interference saturable absorber (SA). In the specially designed SA, linearly polarized light is coupled into a 15-cm-long graded-index multimode fiber (GIMF) through the PM fiber, and then reflected back to the PM structure through a mirror pigtailed with a single-mode fiber (SMF). The modulation depth and saturation peak power are measured to be 1.5% and 0.6 W, respectively. The proposed SA device is incorporated into a novel half-PM erbium-doped fiber oscillator, which generates soliton pulses with 409 fs temporal duration at a 33.3 MHz repetition rate. The proposed fiber laser is compared with a conventional non-PM fiber laser mode-locked by nonlinear polarization evolution (NPE) in terms of optical properties such as spectral bandwidth, pulse duration, and stability performance. Short- and long-time stability tests and superior noise performance corroborate robust mode-locking in this setup.Comment: to be published in Optics and Laser Technolog