Erbium-doped Photonic Crystal Fiber Research Articles

Radiation-resistant flatness-shaped spectrum erbium-doped photonic crystal fiber source employing multiple self-compensating methods.

A novel scheme of radiation-resistant flatness-shaped spectrum erbium-doped photonic crystal fiber source (EDPCFS) employing multiple self-compensating methods is proposed. We first develop a sort of radiation-resistant highly erbium-doped photonic crystal fiber (EDPCF) with the cutoff wavelength of 520 nm, which ensures that the pump light and most energy of the green light from upconversion of Er3+ could participate in photo-annealing to reduce the radiation-induced background attenuation (RIBA) of the EDPCFS under radiation environment. To minimize the spectrum variation from radiation-induced active band attenuation (RIABA), the original spectrum is optimized employing an improved double pumped backward (DPB) configuration. With a gain flattening filter and closed-loop feedback control technology, a radiation-resistant EDPCFS with a linewidth larger than 41 nm is achieved, and it experimentally demonstrates a significantly improved mean-wavelength stability of 0.42 ppm/krad with the output power attenuation of 0.09 dB underγ-irradiation of 200 krad. The novel radiation-resistant EDPCFS proposed is quite feasible for strategic interferometric fiber-optic gyroscopes (IFOGs) working in high-dose radiation environment.

Widely tunable, high optical signal-to-noise ratio erbium-doped photonic crystal fiber laser suitable for acetylene sensing

Narrow line-width fiber lasers are useful in gas-sensing, but systems that are both tunable and stable are rare. Here, we describe a single-wavelength ring cavity erbium-doped photonic crystal fiber laser (ED-PCFL) that can align the acetylene (C2H2) gas absorption peak with high precision and a maximum deviation less than 0.012 nm. Rather than using a combination of erbium-doped fiber and a strong nonlinear fiber, ED-PCF was used as a gain medium to achieve a stable single-wavelength output based on the non-linear polarization rotation effect (NPR). This was selected because ED-PCF has a strong nonlinear effect. We added the dual polarization controllers (PCs) to weaken the homogeneous broadening based on the traditional tunable filter (TF) filtering structure. The results show that these steps improve the tunability of the laser wavelength and enhance the stability of the light source. The final laser had a side-mode suppression ratio as high as 60 dB over 45 nm with a maximum fluctuation in wavelength less than 6 pm. The peak power standard deviation was ∼0.03 dB during the 2 h experimental time. The peak power response of ED-PCFL was studied as a function of C2H2 concentrations, and the calculated R-squared value was 0.993. This means that the ED-PCFL is suitable for C2H2 sensing.

Characterization of Erbium Doped Photonic Crystal Fiber

Photonic crystal fibers (PCFs) which exhibit unique and tremendous optical properties have been undergoing quick growth in recent years. Studies on the characteristics of various types of PCFs have been reported. However, characterization on erbium-doped PCF has not previously been investigated. Therefore, in this paper, an erbium-doped core PCF having 7 rings of hexagonal air holes has been modeled. A perfectly matched layer (PML) is modeled within the PCF structure and simulated using Finite Element Method (FEM) using COMSOL software. The PML is optimized by varying the radius and thickness of the layer. Modal properties of the PCF have been investigated in terms of its effective index of the supported fundamental mode, confinement loss and thickness of the perfectly matched layer. This erbium-doped PCF has a confinement loss of 1.0E-6 at 1500 nm and a maximum effective refractive index of 1.476. This paper gathers useful data, which could be used for studying the characteristics of a PCF.

Temperature-insensitive, gain flattened erbium-doped photonic crystal fiber amplifier: a compatible solution

An all-silica, erbium-doped photonic crystal fiber (PCF) has been investigated numerically to achieve temperature insensitive amplification for optical communication applications. The careful engineering of PCF microstructured air-hole cladding offers two distinct advantages over conventional fibers, namely, compatible mode area and large modal overlap which can be controlled accurately to lower the splice loss and shorten the fiber length respectively. Splice loss as low as 0.22 dB and fiber length as short as 3.25 m for 190 mW pump power and 1 µW signal power, have been achieved in this work. Apart from these two existing advantages, a third advantage has been highlighted and numerically verified in this paper. This third advantage concerns the realization of an athermal long period grating (LPG) filter to flatten the amplifier’s gain spectrum. The LPG which exhibits a gain ripple of 0.29 dB over a 25 nm wavelength band at room temperature (20 °C), does not respond significantly with temperature and sub-dB ripples within 0.64 dB are maintained when temperature changes over a 80 °C range (−20 to +60 °C). This athermal nature of the flattened gain spectrum is attributed to the single material composition of the PCF, which is clearly unachievable with conventional fibers.

平均波长和输出功率稳定性高的掺铒光子晶体光纤超荧光光源的实验研究

平均波长和输出功率稳定性高的掺铒光子晶体光纤超荧光光源的实验研究

Switchable quadruple-wavelength erbium-doped photonic crystal fiber laser based on a polarization-maintaining photonic crystal fiber Sagnac loop filter

Abstract A switchable quadruple-wavelength erbium-doped photonic crystal fiber laser is proposed and demonstrated experimentally by employing a simple linear cavity configuration incorporating a polarization-maintaining photonic crystal fiber Sagnac loop filter. The laser can be switched flexibly from single-wavelength to quadruple-wavelength by adjusting a polarization controller and all of lasing lines locate at fixed wavelength positions in the range of 1556 nm to 1560 nm. The laser individually has a kind of single wavelength and quadruple-wavelength output mode. It also has three and two kinds of dual-wavelength and triple-wavelength output modes, respectively. The laser with good intensity uniformity exhibits excellent wavelength and power stabilities in the experiment.

Investigation of structural dependence of host erbium-doped triangular-lattice PCF on lasing properties and design of high performance laser

A detailed study is presented on the lasing properties of an erbium-doped photonic crystal fiber (PCF) laser. The effects of the host PCF’s structure and laser parameters on continuous-wave laser emission are analyzed by considering the confinement and overlap of pump and signal fields in the gain medium for varying values of pitch, hole diameter, and doping radius. For analysis, we used a finite-difference mode-calculation algorithm devised with standard population and propagation rate-equation solver. Our analysis, applied to an experimentally realized PCF laser, reproduces the observed/reported data, thereby showing the efficacy of our analysis. Finally, a fiber geometry to realize a laser with threshold as low as 6 mW using a short fiber length of 0.52 m is prescribed. The aim of the design is to greatly reduce splice loss with standard single-mode SM28/G.652 fiber while maintaining the optimum performance. These results are new in PCF laser research and should be useful in realizing high performance PCF-based laser devices.

High-stable, double-pass forward superfluorescent fiber source based on erbium-doped photonic crystal fiber

A double-pass forward configuration superfluorescent fiber source (SFS) based on erbium-doped photonic crystal fiber (EDPCF) with a high intrinsic mean wavelength stability is presented. The main factors of SFS instability with temperature variation are analyzed. Optimization of the high-stable SFS is achieved by combining high-performance EDPCF, optimal fiber length, and source structure with fine-tuning pump power. The temperature dependence of the SFS mean wavelength has been reduced to below 0.077 ppm/°C with temperature variation from 70 to −40 °C. To the best of our knowledge, this value is the closest to 0 ppm/°C in the reported references, and these new developments probably constitute an important step for high-accuracy interferometric fiber-optic gyroscope sources.

Switchable multi-wavelength erbium-doped photonic crystal fiber laser based on nonlinear polarization rotation

A multi-wavelength erbium-doped photonic crystal fiber (ED-PCF) ring laser based on nonlinear polarization rotation was demonstrated experimentally. To the best of our knowledge, this study is the first to use a polarization-dependent isolator with an ED-PCF to form an equivalent fiber filter. The intensity-dependent inhomogeneous loss induced by nonlinear polarization rotation was applied to reduce the mode competition caused by ED-PCF. A detailed theoretical analysis using the Jones matrix method to calculate the transfer function of the laser was presented. The theoretical data, which were confirmed by the experimental results, showed that a multi-wavelength with a spacing of approximately 2.26nm was achieved by controlling the polarization controller. The proposed fiber laser with a signal-to-noise ratio higher than 40dB achieved a low threshold power of 30mW. Therefore, stable multi-wavelength outputs with a power fluctuation of less than 2dB were generated at room temperature.

Erbium-doped photonic crystal fiber lasers optimization by microstructure control: experimental study analysis

Two home-made erbium-doped PCFs are used to experimentally study how the PCF microstructures affect the performance of tunable ring lasers made of these fibers. It is found that significant improvement of lasers performance can be obtained. In particular a laser power of 98 mW and slope efficiency of 24 % (to our knowledge the largest reported so far) and also a threshold of 4.5 mW are obtained with the optimal configuration. From the analysis of experimental results it is found that the influence of the microstructure takes place through three mechanisms: overlapping between modal distributions and erbium-doped area, splice losses and passive propagation losses which are mainly due to radiation originated by the finite size microstructure of air holes.

A Switchable Multi-wavelength Erbium-Doped Photonic Crystal Fiber Laser with Linear Cavity Configuration

A switchable multi-wavelength erbium-doped photonic crystal fiber laser with a linear cavity configuration based on a Sagnac loop mirror is proposed and demonstrated experimentally. The laser is based on saturated spectral hole burning and the polarization hole burning effects can be switched among single-wavelength, dual-wavelength, triple-wavelength and quadruple-wavelength outputs at room temperature. The wavelength period of the output spectrum is easily varied by using polarization maintaining fibers of different lengths. The proposed fiber laser has a signal-to-noise ratio of higher than 30 dB and achieves a low threshold power of 37mW. The power fluctuations of the lasing lines are less than 0.54 dB, 1.7 dB and 2.9 dB when the laser operates at single-wavelength, dual-wavelength and triple-wavelength for one hour.

High-stable and broadband erbium-doped superfluorescent photonic crystal fiber source

A high-stable and broadband single-pass backward configuration superfluorescent fiber source based on erbium-doped photonic crystal fiber (EDPCF) is proposed. With the proper EDPCF length, pump power, and a gain flattening filter, we demonstrate that it is possible to create a high-stable and broadband erbium-doped superfluorescent photonic crystal fiber source (SPCFS). This was accomplished by replacing the conventional erbium-doped fiber with the EDPCF, the intrinsic thermal coefficient of which is four times less than the measured conventional erbium-doped fibers. The SPCFS showed that the total output power stability was less than 0.0337%, the 3-dB spectral width was broader than 42 nm, the output spectrum flatness was less than 1 dB, and the mean wavelength stability was less than 2.58 ppm over 6 h at temperatures from 24.3°C to 25.5°C, which approached the requirement for inertial-grade fiber optic gyroscopes.

Dynamic Characterization of Upconversion in Highly Er-Doped Silica Photonic Crystal Fibers

Measurements of time evolution of amplified spontaneous emission for square-wave modulated pump were made on a highly erbium-doped silica photonic crystal fiber and fitted to theoretical results calculated using different formalisms to describe the ${\rm Er}^{3+}$ -ion migration-assisted co-operative upconversion mechanism in the population densities rate equations. The determined characterization parameters are the constant homogeneous upconversion coefficient, 3.0 $\times 10^{-24}~{\rm m}^{3}/{\rm s}$ , the critical radii for upconversion and migration, 10.5 and 14A, respectively, and the rate of clustered ions, 14%. These parameters are analysed and compared to those obtained with continuous-wave pump characterization techniques. Although similar values are obtainable for many parameters using steady-state and dynamic characterization techniques, if a careful enough modelling is carried out, dynamic techniques are preferable to assess the presence of pair-induced quenching.

High-stability erbium-doped photonic crystal fiber source

A single-pass backward configuration superfluorescent fiber source (SFS) based on erbium-doped photonic crystal fiber (EDPCF) with a high mean wavelength stability was proposed. The EDPCF was used to improve the intrinsic temperature dependence of the SFS. Using the optimal EDPCF length of 24.2 m and pump power of 204 mW, a 20.7 ppm mean wavelength stability of a prototype SFS was demonstrated with increased temperature from -40 °C to 60 °C. The mean wavelength had an ultra stability of 10.3 ppm with increased temperature from -20 °C to 60 °C.

Amplifiers and Lasers Based on Erbium-Doped Photonic Crystal Fiber: Simulation and Experiments

In this paper it is shown that, once a particular erbium-doped-silica photonic crystal fiber has been fabricated, the characteristic parameters obtained by means of the technique developed by the authors can be used to properly simulate the main features of optical amplifiers and lasers made of this fiber. This requires assuming that the finite size of the air-holes microstructure makes the overall passive losses per unit length to exhibit an effective dependence on the fiber length. Measurements are performed on a variety of amplifiers and lasers built with pieces of different lengths of two home-made fibers to check the simulation method. A good agreement is found between experimental and simulated results. This means that the proposed method is useful to design optimized erbium-doped photonic crystal fiber amplifiers and lasers for particular applications.

基于掺铒光子晶体光纤超荧光光源的实验研究

基于掺铒光子晶体光纤超荧光光源的实验研究

Polarization-maintaining erbium doped photonic crystal fiber laser

A polarization maintaining erbium-doped photonic crystal fiber laser (PM-Er-PCF), is presented. The laser operates in a ring cavity in the near infrared wavelength range. We believe that it is the first report of the successful realization of a polarization maintaining erbium-doped photonic crystal fiber laser. Single-wavelength and multiwavelength operation of the developed fibre laser was observed. Experimental results show that the laser operates with good output parameter stability over a period of one hour and exhibits a 37 dB signal-to-noise-ratio. We present a detailed description of the design process and of the experimental characterization and validation for the PM-Er-PCF. We also analyze the impact of the photonic crystal structure on the laser parameters.

Tunable and switchable multi-wavelength Erbium-doped photonic crystal fiber ring laser incorporating a length of highly nonlinear photonic crystal fiber

A tunable and switchable multi-wavelength Erbium-doped photonic crystal fiber ring laser incorporating a length of single-mode highly nonlinear photonic crystal fiber is proposed and demonstrated experimentally. Stable dual-wavelength and triple-wavelength operations at room temperature are achieved by employing the highly nonlinear photonic crystal fiber to induce four-wave mixing effect and a polarization controller to vary the polarization states of propagation lights in the laser cavity. The laser cavity is free from any wavelength selection components. The laser obtains maximal 30 dB signal-to-noise ratio and the peak power fluctuations of lasing lines are less than 1.39 dB.

Erbium-doped photonic crystal fiber distributed feedback loop laser operating at 1550 nm

An all-fiber, single-wavelength, erbium-doped photonic crystal fiber (PCF) distributed feedback (DFB) loop laser at 1550.08 nm is proposed and demonstrated experimentally for the first time. Two matched fiber Bragg gratings (FBGs) are used as the selective wavelength components in the loop laser. The optical signal to noise ratio and the 3 dB linewidth of lasing wavelength are greater than 30 dB and less than 0.96 nm, respectively. A low pump power threshold (∼17 mW) is obtained. 10-time repeated scans of the laser output spectra with 1 min interval indicate that the lasing wavelength is rather stable at room temperature. The peak power of the laser has a maximal fluctuation no more than 0.06 dBm within 30 min.

Deep notch filter based on liquid-filled photonic crystal fiber

A deep notch filter in a liquid-filled photonic bandgap fiber (PBGF) realized via filling an erbium-doped solid core photonic crystal fiber with high-index liquid is proposed and demonstrated. The numerical investigation indicates that the notch is formed due to avoid-crossing effect between the fundamental mode and LP02 supermodes. The resonance wavelength of the filter can be tuned by adjusting the temperature of the liquid-filled PBGF and shifts toward short wavelength. The blue-shift speed average is 1.3 nm/°C.