The design of birefringent photonic crystal fiber sensor based on the surface plasmon resonance model is proposed in this paper. This sensor utilizes circular air holes to introduce birefringence into the structure. The effect of geometric parameters on the performance of the sensor has been analysed with the operation wavelength between 600 nm and 800 nm. The sensor is designed to detect refractive index of the analyte between 1.33 and 1.35, which offers average sensitivity of about 4880 nm/RIU and 3940 nm/RIU for HEx11 and HEy11 modes, respectively. Moreover, the proposed sensor has a strong potential for multi-channel/multi-analyte sensing with much higher sensitivity.
Self-similar pulses are one of the domestic and international research hotspots in the field of nonlinear fiber optics because it can suppress optical wave breaking at high energies. The influence of pumping schemes on the characteristics of self-similar pulses in a passively mode-locked Yb-doped fiber laser is theoretically investigated. The temporal profile and optical spectrum of self-similar pulses in passively mode-locked fiber lasers of different pumping schemes are obtained in the simulation. This study focuses on analyzing the influence of gain bandwidth of gain fiber on the pulse duration, peak power, and single-pulse energy of self-similar pulses.
Based on Fabry-Perot structure, a multiple-channel filter is obtained in theory by changing the structure of spacer layers.
This paper is concerned with the design of optical filters, based on thin-film interference, for multichannel optical
communication systems with Ta2O5 and SiO2 materials for 1550 nm operation. The performance of the filter
configuration is analyzed and the numerical results of the optimization parameters, such as central wavelength, 3-dB
bandwidth, figure of merit and ripple in the passband, are reported. The variation of these parameters is also studied for
various modified filter configurations. The angular performance of the filter is investigated in terms of spectral shift of
transmittance towards shorter wavelengths. It is concluded that the width of adjacent routeways can be changed by
changing the structure of spacer layers. The variation of these parameters is also studied for adding irregularly suited
layers. The layer sensitivity of the ultra broadband multichannel thin-film-based optical filter, is thoroughly analysed.
A ring-cavity Er/Yb co-doped fiber laser (EYDFL) was designed and the characteristics was studied in this paper. It used
1064nm Nd:YAG laser as its pump, and the gain medium is a 4.1m-long EYDF. The single longitudinal-mode operation
is realized by introducing a fiber Bragg grating (FBG) as narrow wavelength-selective element, and a section of EDF
not-pumped as saturable absorber. The fiber laser resonator has been optimized, and the stable laser output with single
longitudinal-mode was got. In the simulation and experimental study, the difference of fiber laser output power using
output coupler in different coupling ratio has been studied. The optimal coupling ratio testified in experiments was near
80 percents. The effects and influences of saturable absorber on characteristics of output laser mode are analyzed.
A novel gain-clamped Long wavelength band erbium doped fiber amplifier (L-band EDFA) based on ring erbium-doped
fiber laser cavity was demonstrated. By using a fiber Bragg grating (FBG) at the output end of the amplifier, a portion of
forward conventional band (C-band) amplified spontaneous emission (ASE) was reflected back into the system, this new
design provided a good gain clamping and decreased noise effectively. It used 1480nm laser diode (LD) to pump high
Er3+ −concentration erbium-doped fiber for higher efficiency and lower noise figure (NF). The gain was clamped at
17.5dB with a variation of 0.3 dB from input signal power of -30dBm to -12dBm for a pump power of 180mW. By
adjusting the intra-cavity loss, the gain reached 19.78dB with inputting small signal and NF below 5dB was obtained. At
the longer wavelength (1614nm) of L-band 9.2dB gain was obtained.
A current sensor array which consists of tunable fiber laser, Giant Magnetostrictive Material (GMM) and fiber grating is
presented. The long-haul experiment is operated on the basis of current sensor unit about 21km. In general, the results of
the design of the system is credible and qualified for the designing demand. And then a current sensor array is composed
of four current sensor units in 21km long-haul. The sensing properties of the wavelength divided multiplex (WDM) and
time divided multiplex (TDM) is demonstrated. The wavelength resolution of the measurements is 0.002 nm and current
resolution is 6.55mA, due to the high sensitivity photo detection system. While the work current go up from 1200mA
to2300mA, Sensitivity of the wavelength will be maximum.
A single-mode Er/Yb-codoped short cavity fiber laser was experimented on the basis of previous short cavity fiber laser.
The single-mode operation is realized by using the FBG and a 10cm section of Er/Yb co-doped fiber as a short cavity.
The output power exceeds 1.5mW for pump power of 80mW. The linewidth of output laser was measured as 2MHz at
1532.64nm, and the side mode suppression ratio was 55dB. The single-mode was observed by an interferometer with
free spectrum range (FSR) of 7.5GHz, and the longitudinal-mode fabric is analyzed. Relative intensity noise was less
than -100dB/Hz.
A novel super-fluorescence fiber source (SFS) in the wavelength range that covers the C+L-band with stable spectrum, high output power and high slope efficiency is demonstrated. The topology consists of two stages: the first stage provides primarily the L-band gain spectrum whilst the second is solely for the C-band. These two stages are combined in series. We merely used the low erbium-doped fiber (EDF) 10.8m long as a gain medium in the second stage, which was pumped backward by a 980nm semiconductor laser diode (LD). As a result, the Amplified Spontaneous Emission (ASE) spectrum had a threshold of 5.1mW and a slope efficiency of 13.48% in the C-band. With a 980 nm LD pumping forward at 11-m-long moderate EDF and 58-m-long low EDF in series, L-band ASE was yielded with 52.3 mW threshold and a slope efficiency of 35.82% in the first stage. The ASE in the L-band was put into the second stage through an isolator and combined with C-band ASE as an output then a broad ASE spectrum of C+L-band was observed. The maximum output power of the C+L-band source was 33mW (15.3dBm) and its power stability was better than ±0.02 dB. Through the optimization of fiber parameters and the adjustment of pumping power in both stages, the flatness of ASE spectrum was improved. The optical bandwidth for the SFS output power, which ripples in 3 dB, was 63.7 nm (1536.92-1600.62 nm) of optical bandwidth without gain flattening filter.
Based on the analysis of conventional L-band EDFA we demonstrate a novel structure that improves the L-band amplification performances. In conventional L-band EDFA, 35nm (±1dB) flattened amplification bandwidth from 1565 to 1600 nm is obtained. Small signal gain of 25dB is achieved at 1590 nm with input power of -30dBm and the saturated output power reach to 10dBm. The linear relation between pump power and signal power are demonstrated experimentally. By utilizing a fiber Bragg grating (FBG) with center wavelength of 1550 nm, the population inversion of EDFA is intensified, which gives rise to gain improvement. Experimental results show that the signal gain is enhanced by the FBG by more than 8dB. The use of FBG has also shown a better performance in gain clamping. The amplifier gain is clamped at 25dB with a gain variation of less than 0.5dB for input power as high as -15dBm.
It is performed by optimizing the source that experiments to demonstrate the feasibility of a small laser for EUV contact lithography. Using copper, steel and tungsten targets, the depth of development of DCPA resists exposed through 50 1/mm, 100 1/mm Cu free-standing nets are obtained for times from 10 to 40 min. A method of adding a pinhole is used to estimate the qualities of pattern of developed resist.
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