SNAP structures fabricated by profile design of in-fiber inscribed regions with a femtosecond laser

Fabricating a surface nanoscale axial photonics (SNAP) microresonator with a specific profile is a challenging and important issue since its advent. We propose a powerful approach for the flexible fabrication of the SNAP structures with arbitrary profiles by a femtosecond laser. Our method is to design the profile of the length distribution of the inscribed lines to match the profile of the required SNAP microresonator, and to combine it with other fabrication parameters to precisely control the radius variation of the SNAP structure. In experiments, we demonstrate the design and fabrication of the SNAP structures with the parabolic, semi-parabolic, and bat profiles. The developed approach is expected to be universal for the fabrication of complex high Q-factor SNAP structures, which lays the groundwork for exploring the versatile performances of the SNAP devices.

Random fiber laser based on a partial-reflection random fiber grating for high temperature sensing

A stable single wavelength random fiber laser (RFL) with a partial-reflection random fiber grating (PR-RFG) for high temperature sensing is proposed and demonstrated for the first time, to the best of our knowledge. The PR-RFG is fabricated with the help of a femtosecond laser, with its highest reflection peak significantly higher than all other reflection peaks, which can ensure the stability of this filter-free RFL. Theoretical calculations also show that such a PR-RFG should be designed with reflectivity in the range of ∼30%-90% to obtain one reflection peak significantly higher than other peaks. The threshold of this laser is only 6.4 mW. In addition, the RFL realizes temperature sensing in the range from 25°C to 500°C and has an optical signal-to-noise ratio of up to 70 dB.

Accurate fabrication of SNAP microresonators via a femtosecond laser with multidimensional optimized parameters

Surface nanoscale axial photonics (SNAP) microresonators with nanoscale effective radius variations (ERVs) along the optical fiber axis can be fabricated by inscribing axially oriented lines inside the fiber with a femtosecond laser. Here, we propose the multi-dimensional fabrication parameter system for the femtosecond laser fabrication of SNAP devices and systematically investigate the relationships between the introduced ERV and the multidimensionally controllable fabrication parameters. Specifically, both the qualitative and quantitative processing principles are revealed. As a proof-of-principle, by multidimensionally optimizing the fabrication parameters, we realize a SNAP microresonator with the characteristics of both small axial size and maximal ERV. The achieved ERV is almost 5 times larger than the ERV achieved with the previous unoptimized method. Our work promotes the fs laser inscription technology to be a flexible and versatile approach for fabricating the SNAP devices with ultra-high precision, ultra-low loss and high robustness.

Mutations in CHMP4C cause dilated cardiomyopathy via dysregulation of autophagy

Background

Gene mutations have been implicated in DCM. However, due to the difficulty of clinical genetic diagnosis, more causal genes potentially related to DCM remain to be discovered.

Methods

We screened for gene mutations in more than 400 cases from families with hereditary cardiovascular disease using whole-exome sequencing. Then we validated biological functions of CHMP4C mutations in zebrafish models. To further assess the mechanism of CHMP4C mutations, we evaluated the potential signaling pathway in the cells.

Results

We identification of CHMP4C variants that segregated with DCM variants in four families from a total of 411 families via whole-exome sequencing. We further validate the function of CHMP4C in heart function in zebrafish models and found that over-expression of CHMP4C variants in zebrafish resulted in cardiac malformation, pericardial edema and increased heart rate, consistent with CHMP4C mutation-associated findings in DCM patients. Furthermore, we found that mutations in CHMP4C impaired autophagy and activated apoptosis in HEK293T cells, suggesting that the molecular mechanism of CHMP4C is involved in heart development.

Conclusions

CHMP4C is a novel candidate gene for DCM and may play a critical role in cardiac development by regulating autophagy.

Funding Acknowledgement

Type of funding source: None

Non-invasive myocardial workiIndices derived from left ventricular pressure-strain loops in predicting the response to cardiac resynchronization therapy

Background

Non-invasive left ventricular (LV) pressure-strain loops (PSLs) which generated by combining LV longitudinal strain with brachial artery blood pressure, provide a novel method of quantifying global and segmental myocardial work (MW) indices with potential advantages over conventional echocardiographic strain which is load-dependent. The method has been introduced in echocardiographic software recently, making MW calculations more effectively and rapidly. The aim was to evaluate the role of non-invasive MW indices derived from LV PSLs in the prediction of cardiac resynchronization therapy (CRT) response.

Methods

106 heart failure (HF) patients scheduled for CRT were included for MW analysis. Global and segmental (septal and lateral at the mid-ventricular level) MW indices were accessed before CRT. Response to CRT was defined as ≥15% reduction in LV end-systolic volume at 6-month follow-up in comparison with baseline value.

Results

CRT response was observed in 78 (74%) patients. At baseline, global work index (GWI) and global constructive work (GCW) were significant higher in CRT responders than in non-responders (both P<0.05). Besides, responders exhibited a significantly higher Mid Lateral MW and Mid Lateral constructive work (CW) (both P<0.001) but a significantly lower Mid Septal MW and Mid Septal myocardial work efficiency (MWE), as well as a significantly higher Mid Septal wasted work (WW) than non-responders (all P<0.01). Baseline Mid Septal MWE (OR 0.975, 95% CI 0.959–0.990, P=0.002) and Mid Lateral MW (OR 1.003, 95% CI 1.002–1.004, P<0.001) were identified as independent predictors of CRT response in multivariate regression analysis. Mid Septal MWE ≤42% combined with Mid Lateral MW ≥740 mm Hg% predicted CRT response with the optimal sensitivity of 79% and specificity of 82% (AUC = 0.830, P<0.001).

Conclusion

Mid Septal MWE and Mid Lateral MW can successfully predict response to CRT, and their combination can further improve the prediction accuracy. Assessment of MW indices before CRT could identify the marked misbalance in LV myocardial work distribution and has the potential to be widely used as a reliable complementary tool for guiding patient selection in clinical practice.

Funding Acknowledgement

Type of funding source: None

Multi-wavelength random fiber laser with switchable wavelength interval

A random fiber laser with flexible wavelength interval switching is proposed and demonstrated through two switching methods. One is to change the effective structure of the laser cavity by controlling the switches of 980 nm pump laser diodes (LDs) for erbium-doped fibers (EDFs), which can achieve the switching of the wavelength interval from a single Brillouin frequency shift (BFS) of 0.088 nm to a double BFS of 0.176 nm. Another method is to manipulate the gain provided by the two EDF amplifiers by controlling the power of the three 980 nm LDs, thereby realizing the optical switching of the wavelength interval. This kind of wavelength interval switchable random fiber laser increases the flexibility and functionality of multi-wavelength light sources, and further expands the application range of the random fiber lasers. Furthermore, the alternative wavelength interval switching mechanisms with simple structure enable it to meet the application requirements of various occasions.

Auto-Phase-Locked Time-Resolved Luminescence Detection: Principles, Applications, and Prospects

Time-resolved luminescence measurement is a useful technique which can eliminate the background signals from scattering and short-lived autofluorescence. However, the relative instruments always require pulsed excitation sources and high-speed detectors. Moreover, the excitation and detecting shutter should be precisely synchronized by electronic phase matching circuitry, leading to expensiveness and high-complexity. To make time-resolved luminescence instruments simple and cheap, the automatic synchronization method was developed by using a mechanical chopper acted as both of the pulse generator and detection shutter. Therefore, the excitation and detection can be synchronized and locked automatically as the optical paths fixed. In this paper, we first introduced the time-resolved luminescence measurements and review the progress and current state of this field. Then, we discussed low-cost time-resolved techniques, especially chopper-based time-resolved luminescence detections. After that, we focused on auto-phase-locked method and some of its meaningful applications, such as time-gated luminescence imaging, spectrometer, and luminescence lifetime detection. Finally, we concluded with a brief outlook for auto-phase-locked time-resolved luminescence detection systems.

Dual interference effects in a line-by-line inscribed fiber Bragg grating

Fiber Bragg grating (FBG) usually can be seen as a stack of Fabry-Perot (FP) cavities, which result in strong Bragg resonance through multi-cavity FP interference. In this Letter, we report surprising and interesting dual interference effects in a line-by-line (LBL) inscribed FBG with a femtosecond laser. Besides the well-known FP effect, the equivalent Mach-Zehnder interference (MZI) effect caused by mode interference can also be observed in the LBL FBG simultaneously. The experimental results of the comparison between the LBL FBGs and the point-by-point inscribed FBGs show that the dual interference effects are merely observed in the LBL FBGs. Meanwhile, the achieved MZI exhibits a strong polarization dependence. Sharing the merits of the FBG and MZI simultaneously, the achieved optical fiber device may find potential applications in optical fiber communication, fiber lasers, and multi-parameter sensor systems.

Mode-locked and Q-switched mode-locked fiber laser based on a ferroferric-oxide nanoparticles saturable absorber

We demonstrated an ultrafast erbium-doped fiber laser (EDFL) based on ferroferric-oxide (Fe₃O₄) nanoparticles as a saturable absorber (SA). The investigated SA was based on magnetic fluid deposited on the end face of a fiber ferrule connector. When the SA was inserted into an EDFL cavity, a stable 2.93 ps mode-locked pulse can be achieved by adjusting the intra-cavity polarization controller. The pulse had a central wavelength of 1572.39 nm and a 3 dB bandwidth of 1.39 nm. We also obtained Q-switched mode-locked pulses at 1593.4 nm. The repetition frequency and the temporal width of the Q-switched pulse envelope varied with the pump power. When the pump power reached 225 mW, the maximum average output power and the pulse envelope energy were up to 4.51 mW and 235.5 nJ. To the best of our knowledge, this is the first time that mode-locked and Q-switched mode-locked pulses have been obtained in a fiber laser based on Fe₃O₄ nanoparticles.

Dark solitons in the exploding pulsation of the bright dissipative soliton in ultrafast fiber lasers

Soliton explosion is an extremely pulsating behavior of the bright dissipative soliton (DS) in ultrafast lasers. By numerical simulation, we find that the dark soliton (DAS) can coexist with the bright soliton during the exploding process. The collapsed temporal structure of the exploding soliton is induced by the DASs. We reveal the birthing, evolving, and decaying of the DASs inside the bright DS. The time-frequency analysis of the exploding soliton helps us better understand the temporal and spectral structures of the exploding soliton, which might be useful for real-time spectroscopy of the coexisting dark and bright solitons during the soliton explosion.

Spectrally resolved luminescence lifetime detection for measuring the energy splitting of the long-lived excited states

Molecular motion plays an important role in the reverse intersystem crossing of thermally activated delayed fluorescence (TADF) materials, since the conformation varies as the molecule vibrates, leading to potential changes in the energies of excited states. Although many theoretical simulations have researched the relationship between the excited states and the molecular conformations, there are still few experimental results showing the energy level difference between different long-lived excited states. Herein, a novel method for measuring spectrally resolved luminescence lifetimes is proposed to detect the energy splitting of the long-lived excited states of a classical TADF molecule, BTZ-DMAC. A set of the time-gated luminescence spectra with different delay times were captured by a spectrograph equipped on an auto-phase-locked system, and then used for lifetime analysis at each wavelength. Unlike traditional measurement techniques, the proposed novel method does not require ultrafast laser, high-speed detector and any phase matching circuitry, thus significantly reducing the cost. This method revealed a definite energy gap between the two excited states of BTZ-DMAC with different lifetimes, indicating different conformations caused by molecular vibration. This low-cost method could be also used to detect many other luminescence materials for investigating the detail mechanisms of multiple excited states.

Rectangular SNAP microresonator fabricated with a femtosecond laser

Surface nanoscale axial photonics (SNAP) microresonators, which are fabricated by nanoscale effective radius variation (ERV) of the optical fiber with subangstrom precision, can be potentially used as miniature classical and quantum signal processors, frequency comb generators, and ultraprecise microfluidic and environmental optical sensors. Many of these applications require the introduction of nanoscale ERV with a large contrast α, which is defined as the maximum shift of the fiber cutoff wavelength introduced per unit length of the fiber axis. The previously developed fabrication methods of SNAP structures, which used focused CO₂ and femtosecond laser beams, achieved α∼0.02  nm/μm. Here we develop a new, to the best of our knowledge, fabrication method of SNAP microresonators with a femtosecond laser, which allows us to demonstrate a 50-fold improvement of previous results and achieve α∼1  nm/μm. Furthermore, our fabrication method enables the introduction of ERV that is several times larger than the maximum ERV demonstrated previously. As an example, we fabricate a rectangular SNAP resonator and investigate its group delay characteristics. Our experimental results are in good agreement with theoretical simulations. Overall, the developed approach allows us to reduce the axial scale of SNAP structures by an order of magnitude.

Association between methylenetetrahydrofolate reductase polymorphisms and non-syndromic cleft lip with or without palate susceptibility: an updated systematic review and meta-analysis

Methylenetetrahydrofolate reductase (MTHFR) polymorphisms are thought to be involved in the development of cleft lip with or without cleft palate (NSCL/P), but published results are contradictory. We therefore designed an updated meta-analysis to pool eligible studies and to evaluate further the possible relations between MTHFR polymorphisms (c.677C>T and c.1298A>C) and susceptibility to NSCL/P. A comprehensive search based on PubMed, Medline, Web of Science, and Embase databases was made up to February 2018. Twenty-three case-control and 10 case-parent trio studies (including 1149 cases and 1161 controls) were retrieved. Odds ratio (OR) with 95% CI were used to estimate the pooled strength of association under different genetic models. The Q test and I² test were used to estimate heterogeneity among studies, the quality of which was assessed using the Newcastle-Ottawa scale. In the MTHFR c.677C>T polymorphism group, there were significant overall results for the recessive (OR 1.231, 95%CI 1.092 to 1.387) and homozygote (OR 1.252, 95%CI 1.078 to 1.456) models. Subgroup analysis by subjects and ethnicity identified only associations in European mothers for the recessive model and the homozygote model. For the c.1298A>C group, there were no significant results for either European or Asian patients for all genetic models. The MTHFR c.677C>T polymorphism might increase susceptibility to NSCL/P in European mothers, but was negatively associated in Asian patients, and the MTHFR c.1298A>C polymorphism is not involved in the development of NSCL/P in either European or Asian patients.

P6501Recurrent genetic aberrations in bicuspid aortic valve disease patients with isolated severe aortic regurgitation

Background

The etiology of bicuspid aortic valve disease (BAVD) is still unclear. Recent studies have demonstrated elevated prevalence of genetic defects in BAV patients with root phenotype, which includes aortic regurgitation and root-predominant dilatation.

Purpose

The present study intended to illustrate the feature of genetic defects among early-onset BAV patients with isolated severe aortic regurgitation.

Methods

From June 2015 to December 2017, whole exome sequencing was performed upon 27 BAVD patients with isolated severe aortic regurgitation under 45 years in our institution. Patients were categorized into right-left (R-L, n=16) and non-RL (n=11) cusp fusion types, and those with complex cardiac defects were excluded from the present study.

Results

Among 27 patients with a median age of 30.5 (18–44) years, only one was female with a rare left-non-coronary cusp fusion type. The prevalence of root phenotype was markedly higher in RL patients (56.3% vs 9.1%, p=0.018). In RL patients, the numbers of rare genetic variants (RGVs) were 15 in extracellular matrix genes, 8 in TGF-β signaling pathway genes, 2 in smooth muscle cell contraction apparatus genes, and 3 in familiar BAV related genes. In non-RL patients, the number of RGVs were 15, 3, 4, and 5, respectively. On the other hand, the number of RGVs in above gene clusters were 9, 6, 3, 2 in patients with a root phenotype, and 21, 5, 3, 6 in those without. Eight recurrent genetic variants were identified in 6 genes (see Table). An interesting observation was that ADAMTS2 variants were exclusively found among non-RL patients without root phenotype, as FBN2 variants among RL patients with root phenoype.

Recurrent Rare Genetic Variants Gene Reference sequence Variant 1000G 1000G-East Asia Patients TGFBR2 NM_001024847.2 p.Val216Ile/c.646G>A 0.004 0.018 A16, A23 TGFBR2 NM_001024847.2 p.Thr340Met/c.1019C>T 0.003 0.015 A03, A05, A07 ADAMTS2 NM_014244.4 p.Gly1169Val/c.3506G>T 0.0044 0.021 A03, A15 FBN2 NM_001999.3 p.Gly475Val/c.1424G>T 0.0004 0.002 A19, A24 ELN NM_001278939.1 p.Pro93Leu/c.278C>T 0.0014 0.0069 A22, A26 COL4A5 NM_033380.2 p.Gly953Val/c.2858G>T 0.0079 0.03 A11, A17 MYLK NM_053025.3 p.Ser243Trp/c.728C>G 0.0002 0.001 A01, A02 MYLK NM_053025.3 p.Asp717Tyr/c.2149G>T 0.0024 0.011 A04, A21

Conclusion

Recurrent genetic variants could be identified in a cohort of early-onset BAVD patients with isolated severe aortic regurgitation and staggering male predominance. The incidence and clinical relevance of these variants should be validated in an extended real-world BAV cohort.

P916The effect of a novel, user-friendly, transcatheter edge-to-edge mitral valve repair device in a porcine model of mitral regurgitation

Objective

A new technique has been devised to treat mitral regurgitation (MR) through the transapical route by replicating the edge-to-edge repair surgery. This system encompasses an easy-to-use leaflet clamp and a smaller-sized delivery system (14F–16F). We aimed to evaluate the effectiveness of this device in a porcine model of acute MR.

Methods

Acute MR was induced in 36 anesthetized porcine subjects by severing the major chordae supporting the corresponding segment of the leaflet. This device was then transapically implanted on the prolapsing segment under 3D epicardial echocardiographic guidance. All of the animals were killed 30 days after the procedure to verify the proper location of the implanted devices.

Results

Cutting the major chordae induced an eccentric MR jet (MR grade: 3+, 27.8%/4+, 72.2%) in all of the animals. Every single pig was then successfully implanted with one clamp. The duration of catheterization ranged from 18 to 40 minutes. Overt MR reduction was observed following the procedure through echocardiography; residual MR was mild in 8 cases, trivial in 19 cases, and absent in 9 cases. In terms of hemodynamic parameters, the mean and maximum mitral valve pressure gradients were increased significantly (p<0.01), but these values were less than 4 mmHg in all of the cases. Autopsy demonstrated that all but one device were precisely placed to clip the prolapsing segment of the mitral valve, and there was no evidence of thrombosis, thromboembolism or impairment of the cardiac structure.

Table 1. Changes in hemodynamic parameters, cardiac size, and functional parameters after the procedure Preoperation Postoperation P value MR-maxA (mm2) 7.27±2.13 1.54±1.29 0.000 MVPG-max (mmHg) 1.95±0.47 3.66±0.62 0.000 MVPG-mean (mmHg) 0.87±0.31 1.7±0.28 0.000 LVEDD (mm) 46.08±2.85 46.44±3.53 0.239 LVESD (mm) 29.11±3.44 29.08±3.62 0.940 LVEF (%) 66.53±6.4 67.14±4.93 0.256 LAD (mm) 35.75±2.24 36.42±1.99 0.057 LAA (mm2) 12.95±2.22 12.64±1.55 0.301

Figure 1

Conclusions

Transapical implantation of the novel mitral valve repair device is effective and safe in reducing acutely induced MR in pigs; thus, suggesting that it has great potential for clinical benefit in patients with MR.

Acknowledgement/Funding

Shanghai Science and Technology Committee

Spatially distributed delay line interferometer based on transmission Bragg scattering

A novel approach for a delay line interferometer (DLI) based on transmission Bragg scattering is proposed. We have numerically and experimentally demonstrated for the first time, to the best of our knowledge, that a Bragg grating (BG) can deliver the functionality of a DLI in its transmission mode along a single common interfering optical path, instead of the conventional DLI implementation with two interfering optical paths. As a proof of concept, phase-modulated fiber BGs have been designed and fabricated, showing the desired functionality in the transmission mode of the BG. The proposed approach is applicable to any kind of BG technology, such as volume BGs, dielectric mirrors, silicon photonics, and other optical waveguide-based Bragg structures.

Pulsating soliton with broadened Kelly sidebands in an ultrafast fiber laser

We experimentally observed a novel pulsating soliton state with broadened Kelly sidebands in an ultrafast laser. Through simulations, we found that the synchronized and unsynchronized resonant dispersive waves coexisted in the laser. The incoherent interaction between the unsynchronized dispersive waves and soliton resulted in oscillation of the intensity and central wavelength of the soliton. The frequencies of the Kelly sidebands oscillated with the soliton, resulting in their spectral broadening when measured by an optical spectrum analyzer. The numerical results agreed qualitatively well with the experiments. Our results are novel and useful for understanding the chaotic dynamics and designing of the ultrafast fiber laser.

Fiber Bragg grating sensor interrogation system based on an optoelectronic oscillator loop

In this article, we propose and experimentally demonstrate a fiber Bragg grating (FBG) sensor interrogation technique based on an optoelectronic oscillator (OEO). The main components of the OEO loop in this proposed scheme contains an electro-optic modulator (EOM), a section of dispersive element, an electric filter, and a photodiode (PD). The reflection signal of the FBG sensor is functioning as the optical source of the OEO. The oscillating frequency of the OEO is determined by the overall time delay of the OEO loop. Due to the dispersive element in the loop, time delay of the OEO loop is a function of the OEO optical source wavelength. As a result, the wavelength change of the FBG can be converted into the oscillating frequency shift of the OEO. A proof-of-concept FBG based axial strain sensing experiment is carried out. The experimental results show that the frequency of the OEO generated microwave signals have a good linear relationship with the axial strain applied to the FBG. The sensitivity is about 58 Hz/με when using dispersion compensation fiber (DCF) with dispersion of -120 ps/(nm*km) as the dispersive medium and tracking the microwave signal with frequency near 2056.4 MHz, which is consistent with the theoretical calculation. The proposed method can also be applied to interrogate optical sensors based on detecting the wavelength change of the optical signals.

Stable and low-threshold random fiber laser via Anderson localization

We report a stable and low-threshold Er-doped random fiber laser (RFL) based on a femtosecond-laser-inscribed random-distributed-grating array (RDGA) as the random feedback. The RDGA had a reflectivity of 93.5%, and its properties were numerically analyzed based on the transfer matrix method. The threshold of the laser was significantly reduced to 5.7 mW, and the linewidth was ~0.4 pm near the threshold as the Anderson localization effect existing in the RDGA significantly improved the laser quality factor (4 × 10⁶). In addition, we propose a method to select RFL lasing modes by stretching a fiber grating filter used in the cavity with different axial strains. The center wavelength hardly drifted and the maximum jitter value of the peak power was less than 0.12 dB over 1 hour for the selected three lasing modes, which indicated that our laser operation was quite stable.

Vitamin B6 catabolism and lung cancer risk: results from the Lung Cancer Cohort Consortium (LC3)

BACKGROUND

Increased vitamin B6 catabolism related to inflammation, as measured by the PAr index (the ratio of 4-pyridoxic acid over the sum of pyridoxal and pyridoxal-5'-phosphate), has been positively associated with lung cancer risk in two prospective European studies. However, the extent to which this association translates to more diverse populations is not known.

MATERIALS AND METHODS

For this study, we included 5323 incident lung cancer cases and 5323 controls individually matched by age, sex, and smoking status within each of 20 prospective cohorts from the Lung Cancer Cohort Consortium. Cohort-specific odds ratios (ORs) and 95% confidence intervals (CIs) for the association between PAr and lung cancer risk were calculated using conditional logistic regression and pooled using random-effects models.

RESULTS

PAr was positively associated with lung cancer risk in a dose-response fashion. Comparing the fourth versus first quartiles of PAr resulted in an OR of 1.38 (95% CI: 1.19-1.59) for overall lung cancer risk. The association between PAr and lung cancer risk was most prominent in former smokers (OR: 1.69, 95% CI: 1.36-2.10), men (OR: 1.60, 95% CI: 1.28-2.00), and for cancers diagnosed within 3 years of blood draw (OR: 1.73, 95% CI: 1.34-2.23).

CONCLUSION

Based on pre-diagnostic data from 20 cohorts across 4 continents, this study confirms that increased vitamin B6 catabolism related to inflammation and immune activation is associated with a higher risk of developing lung cancer. Moreover, PAr may be a pre-diagnostic marker of lung cancer rather than a causal factor.

Efficient postprocessing technique for fabricating surface nanoscale axial photonics microresonators with subangstrom precision by femtosecond laser

We demonstrated the subangstrom precise correction of surface nanoscale axial photonics (SNAP) micro-resonators by the femtosecond (fs) laser postprocessing technique for the first time. The internal stress can be induced by fs laser inscriptions in the fiber, causing nanoscale effective radius variation (ERV). However, the obtained ultraprecise fabrication usually undergoes multiple tries. Here, we propose a novel postprocessing technique based on the fs laser that significantly reduces the ERV errors and improves the fabrication precision without iterative corrections. The postexposure process is achieved at the original exposure locations using lower pulse energy than that in the initial fabrication process. The results show that the ERV is nearly proportional to the pulse energy of the postexposure process. The slope of the ERV versus the pulse energy is 0.07 Å/nJ. The maximum of the postprocessed ERV can reach 8.0 Å. The repeatability was experimentally verified by accomplishing the correction on three SNAP microresonators with the precision of 0.75 Å. The developed fabrication technique with fs laser enables SNAP microresonators with new breakthrough applications for optomechanics and filters.

Spatio-spectral dynamics of the pulsating dissipative solitons in a normal-dispersion fiber laser

For the first time, to the best of our knowledge, we observed the pulsating dissipative solitons in a mode-locked fiber laser at normal dispersion using the dispersive-Fourier transformation technology. The artificial saturable absorbers, as well as the birefringent filter formed by the nonlinear polarization rotation, make the polarization controller an effective component to adjust the laser state from stationary to pulsating. The pulsating dissipative solitons are accompanied with the spectrum breathing and oscillating structures due to the nonlinear pulse propagation. Our results can enhance the understanding of the pulsating solitons in the dissipative systems.