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1.
Optimization control of modulation-instability gain in photonic crystal fibres with two-zero dispersion wavelengths 下载免费PDF全文
We design three kinds of photonic crystal fibres (PCF)
with two zero-dispersion wavelengths (ZDWs) using the improved full
vector index method (FVIM) and finite-difference frequency domain
(FDFD) techniques. Based on these designed fibres, the effect of
fibre structure, pump power and wavelength on the modulation
instability (MI) gain in the anomalous dispersion region close to
the second ZDW of the PCFs is comprehensively analysed in this paper.
The analytical results show that an optimal MI gain can be obtained
when the optimal pump wavelength (1530~nm) is slightly shorter than
the second ZDW (1538~nm) and the optimal pump power is 250~W.
Importantly, the total MI gain bandwidth has been increased to 260~nm
for the first time, so far as we know, for an optimally-designed fibre
with Λ = 1.4~nm and d/Λ = 0.676, and
the gain profile became much smoother. The optimal pump wavelength
relies on the second ZDW of the PCF whereas the optimal pump power
depends on the corporate operation of the optimal fibre structure and
optimal pump wavelength, which is important in designing the most
appropriate PCF to attain higher broadband and gain
amplification. 相似文献
2.
Efficient collinear frequency tripling of femtosecond laser with compensation of group velocity delay 下载免费PDF全文
This paper demonstrates an approach that negative uniaxial crystal
has a relative anomalous dispersion effect which can compensate group
velocity delay, and applies this approach to nonlinear frequency
conversion of an ultrafast laser field. High efficiency of the third
harmonic generation is experimentally fulfilled by adopting a
collinear configuration of doubing-compensation-tripling system.
Through finely adjusting the incident angle and optical axis direction
of the compensation plate, it obtains ultraviolet (UV) output energy of
0.32~mJ centered at 270~nm with spectral bandwidth of 2~nm when
input beam at 800~nm was 70~fs pulse duration and 6~mJ pulse energy
which was extracted from Ti:sapphire laser system by a diaphragm,
corresponding to an 800-to-270~nm conversion efficiency of 5.3%
and a factor-of-1.6 improvement in the third harmonic generation of
UV band in comparison with a general conventional configuration.
Furthermore, when the full energy of 18~mJ from a Ti:sapphire laser system
was used and optimized, the UV emission could reach 0.83~mJ. 相似文献
3.
High efficiency and broad bandwidth grating coupler between nanophotonic waveguide and fibre 下载免费PDF全文
A high efficiency and broad bandwidth grating coupler
between a silicon-on-insulator (SOI) nanophotonic waveguide and fibre
is designed and fabricated. Coupling efficiencies of 46\% and
25\% at a wavelength of 1.55~μ m are achieved by simulation
and experiment, respectively. An optical 3~dB bandwidth of 45~nm
from 1530~nm to 1575~nm is also obtained in experiment. Numerical
calculation shows that a tolerance to fabrication error of 10~nm
in etch depth is achievable. The measurement results indicate that
the alignment error of ±2~μ m results in less than 1~dB
additional coupling loss. 相似文献
4.
Spacing-adjustable and wavelength-tunable multiwavelength fibre laser with nonlinear Brillouin gain and birefringence fibre loop mirror 下载免费PDF全文
This paper demonstrates a room-temperature multiwavelength
fibre laser with spacing-adjustability and wavelength-tunability.
The nonlinear gain of self-excited stimulated Brillouin scattering
can suppress mode competition induced by homogeneous broadening of
Erbium-doped fibre. With the use of a birefringence fibre loop
filter, the wavelength spacing can be adjusted by changing the
length of the used birefringence fibre, and the lasing wavelengths
can be finely tuned through modifying the filtering profile of the
birefringence filter. Multiwavelength output with spectral spacing
as small as 0.076~nm and a wavelength number of more than 80 has been
successfully produced. 相似文献
5.
High energy and long pulse generation with high-birefringence photonic crystal fibre and laser-diode pumped regenerative amplifier 下载免费PDF全文
We report on the generation of a high energy and long
pulse for pumping optical parametric chirped-pulse amplification
(OPCPA) by a high-birefringence photonic crystal fibre (HB-PCF) and
a laser-diode-pumped regenerative chirped pulse amplifier. Using the
femtosecond pump pulse centred at 815~nm, a 1064~nm soliton pulse is
produced in the HB-PCF. After injecting it into an Nd:YAG
regenerative amplifier with the glass etalons, a narrow-band
amplified pulse with an energy of $\sim $4~mJ and a duration of 235
ps is achieved at a repetition rate of 10~Hz, which is suitable for
being used as a pump source in the 800~nm OPCPA system. 相似文献
6.
Numerical and experimental study on coherent beam combining of fibre amplifiers using simulated annealing algorithm 下载免费PDF全文
We present the numerical and experimental study on
the coherent beam combining of fibre amplifiers by means of simulated
annealing (SA) algorithm. The feasibility is validated by the Monte
Carlo simulation of correcting static phase distortion using SA
algorithm. The performance of SA algorithm under time-varying phase
noise is numerically studied by dynamic simulation. It is revealed
that the influence of phase noise on the performance of SA algorithm
gets stronger with an increase in amplitude or frequency of phase
noise; and the laser array that contains more lasers will be more
affected from phase noise. The performance of SA
algorithm for coherent beam combining is also compared with a widely
used stochastic optimization algorithm, i.e., the stochastic
parallel gradient descent (SPGD) algorithm. In a proof-of-concept
experiment we demonstrate the coherent beam combining of two 1083~nm
fibre amplifiers with a total output power of 12~W and 93%
combining efficiency. The contrast of the far-field coherently
combined beam profiles is calculated to be as high as 95%. 相似文献
7.
8.
High efficiency continuous-wave tunable signal output of an intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate 下载免费PDF全文
In this paper we report on a continuous-wave (CW) intracavity singly
resonant optical parametric oscillator (ICSRO) based on periodically
poled LiNbO3 (PPLN) pumped by a diode-end-pumped CW
Nd:YVO4 laser. Considering the thermal lens effects and
diffraction loss, an optical ballast lens and a near-concentric
cavity are adopted for better operation. Through varying the grating
period and the temperature, the tunable signal output from 1406~nm
to 1513~nm is obtained. At a PPLN grating period of 29~μ m and a
temperature of 413~K, a maximum signal output power of 820~mW at
1500~nm is achieved when the 808~nm pump power is 10.9~W, leading to
an optical-to-optical conversion efficiency of 7.51%. 相似文献
9.
Petr Hlubina 《Optik》2005,116(10):469-474
Spectral-domain intermodal interference is analysed theoretically at the output of a few-mode optical fibre alone and at the output of the optical fibre in a tandem configuration with a Michelson interferometer. The theoretical analysis is performed under general measurement conditions when a broadband source and a low-resolution spectrometer of a Gaussian response function are considered and when the first- and second-order intermodal dispersion effects in the optical fibre are taken into account. The theoretical analysis is performed for two different examples of dispersion curves of a two-mode optical fibre and the effect of the limiting factors is specified. 相似文献
10.
An all-solid-state high power quasi-continuous-wave tunable dual-wavelength Ti:sapphire laser system using birefringence filter 下载免费PDF全文
This paper describes a tunable dual-wavelength Ti:sapphire laser system with
quasi-continuous-wave and high-power outputs. In the design of the laser, it
adopts a frequency-doubled Nd:YAG laser as the pumping source, and the
birefringence filter as the tuning element. Tunable dual-wavelength outputs
with one wavelength range from 700~nm to 756.5~nm, another from 830~nm to 900mn
have been demonstrated. With a pump power of 23~W at 532~nm, a repetition rate
of 7~kHz and a pulse width of 47.6~ns, an output power of 5.1~W at 744.8~nm and
860.9~nm with a pulse width of 13.2~ns and a line width of 3~nm has been
obtained, it indicates an optical-to-optical conversion efficiency of
22.2{\%}. 相似文献
11.
Petr Hlubina 《Optics Communications》2002,210(3-6):225-232
Spectral-domain intermodal interference is analysed theoretically at the output of a few-mode optical fibre alone and at the output of the optical fibre in a tandem configuration with a Michelson interferometer. The theoretical analysis is performed under general measurement conditions when a light source of a given spectral bandwidth and a spectrometer of a given spectral bandpass are considered and when first- and second-order intermodal dispersion effects in the optical fibre are taken into account. Thus, the effect of a variable spectral bandpass of a low-resolution spectrometer on the spectral fringe visibility functions for a two-mode optical fibre of known intermodal dispersion is specified. 相似文献
12.
A new type of all-fibre Sagnac interferometer composed of two loops
is proposed and analysed in detail. It can be used with a very long
transmission line while maintaining excellent performance
characteristics due to the automatic compensation of any
birefringence effects in the trunk fibre. Preliminary experiments at
1310~nm wavelength with a 70~km long trunk fibre demonstrated an
interference visibility as high as 98%, indicating that this
scheme has promising potential applications. 相似文献
13.
A corner-pumped type is a new pumping type in the
diode-pumped all-solid-state lasers, which has the advantages of
high pump efficiency and favourable pump uniformity. A highly
efficient corner-pumped Nd:YAG/YAG composite slab laser is
demonstrated in this paper. The maximal continuous-wave output power
of the 1064~nm laser is up to 18.57~W with a slope efficiency and an
optical-to-optical conversion efficiency of 44.9{\%} and 39.8{\%},
respectively. Inserting an acousto-optic $Q$-switch in the cavity,
the highest average output power of the quasi-continuous wave
1064~nm laser of 6.73~W is obtained at a repetition rate of
9.26~kHz. The experimental results show that a corner-pumped type is
a kind of feasible schedules in the design of diode-pumped
all-solid-state lasers with low or medium output powers. 相似文献
14.
For laser internal therapy in medical applications, optical fibres are required to propagate the laser beam. The far-field pattern of the laser beam at the exit face of the optical fibre is studied using a multimode step-index fibre and a graded index Selfoc fibre. The degree of dispersion, or the output angular distribution, of the beam passing through the Selfoc fibre is much smaller than that passing through the multimode step-index fibre. Consequently, the energy density in the far-field pattern of the beam passing through the Selfoc fibre is very much larger than that for the beam passing through the multimode step-index fibre. It is concluded that the Selfoc fibre is more effective in laser internal therapy. 相似文献
15.
O. Lopez A. Amy-Klein C. Daussy C. Chardonnet F. Narbonneau M. Lours G. Santarelli 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,48(1):35-41
RF frequency transfer over an urban 86 km fibre has
been demonstrated with a resolution of 2×10-18 at one day
measuring time using an optical compensator. This result is obtained with a
reference carrier frequency of 1 GHz, and a rapid scrambling of the
polarisation state of the input light in order to reduce the sensitivity to
the polarisation mode dispersion in the fibre. The limitation due to the
fibre chromatic dispersion associated with the laser frequency fluctuations
is highlighted and analyzed. A preliminary test of an extended compensated
link over 186 km using optical amplifiers gives a resolution below
10-17 at 1 day. 相似文献
16.
为满足现代信息化战争对超宽带行波管的需求,对2~18 GHz超宽带行波管的高频慢波结构进行了研究分析。在传统宽带行波管的基础上引入非翼片加载段的正常色散特性,首次实现2~18 GHz 超宽带高频慢波结构设计,最大带宽达到9∶1。同时输出端螺旋线螺距调整为正渐变分布,能够进一步优化低频段二次谐波抑制比,提高高频段饱和输出功率。结果表明,全频带的基波输出功率达到100 W,二次谐波抑制比优于?3 dBc,2 GHz频点二次谐波抑制比优于?5 dBc,为超宽带大功率器件的设计提供了理论基础。 相似文献
17.
A.A. Hamza A.E. Belal T.Z.N. Sokkar H.M. EL-Dessouky M.A. Agour 《Optics and Lasers in Engineering》2007,45(1):145-152
Opto-thermal device attached to automate Fizeau interferometer is used to investigate the influence of temperature on opto-thermal properties of multimode graded-index (GRIN) optical fibre in the range from 27 to 54 °C. The effect of temperature on the refractive index profile of fibre is studied. The optical parameters and the opto-thermal coefficient of this fibre are determined. Also the variation of oscillation and dispersion energies, zero dispersion wavelengths, coupling efficiency, normalised frequency, number of propagation modes with the temperature and the material dispersion with the wavelength at different temperatures are calculated. Microinterferograms are given for illustration. 相似文献
18.
High birefringence, low loss terahertz photonic crystal fibres with zero dispersion at 0.3 THz 下载免费PDF全文
A terahertz photonic crystal fibre (THz-PCF) is designed for terahertz wave propagation. The dispersion property and model birefringence are studied by employing the finite element method. The simulation result reveals the changing patten of dispersion parameter versus the geometry. The influence of the large frequency band of terahertz on birefringence is also discussed. The design of low loss, high birefringence THz-PCFs with zero dispersion frequency at 0.3 THz is presented. 相似文献
19.
Guo Jun Yan Yang Meng Lin 《International Journal of Infrared and Millimeter Waves》2005,26(5):657-667
The dispersion relation of a corrugated—wall resonator with an inner coaxial structure has been analyzed as well as the effects of the corrugation period, amplitude and the radius of the coaxial structure on it. Furthermore, we got an output power of 2.1GW at frequency 11.09GHz in a non-uniform slow wave structure by using the PIC simulation software—MAGIC. 相似文献
20.
Linearly polarised three-colour lasing emission from an evanescent wave pumped and gain coupled fibre laser 下载免费PDF全文
A novel Whispering--Gallery--Mode (WGM) fibre laser,
emitting linearly polarised three-colour light, is demonstrated by
pumping and gain coupling with evanescent waves. The pump light is
longitudinally coupled into a bare optical fibre immersed in a dye
solution of lower refractive index. The dye molecules around the
bare fibre are excited by the evanescent waves of pump light when
they propagate along the fibre in a total internal reflection. When
the pump beam within the fibre is a meridian beam, the WGM lasing
emission from the fibre laser is a linearly polarised transverse
electric wave, while it is a mixed wave of the linearly polarised
transverse electric and magnetic waves if the pump beam is a skew
beam within the fibre. Because the excited molecules are located
within the evanescent field of WGM, a good spatial overlap between
the dye gain and the evanescent field leads to a high pumping
efficiency and a longer gain distance along the fibre. Once the bare
fibre is inserted into three glass capillaries filled with Rhodamine
6G, 610 and 640 dye solutions, respectively, WGM laser oscillations
at the wavelengths of 567--575, 605--614 and 656--666~nm occur
simultaneously, and a linearly polarised three-colour lasing
emission is achieved in a single optical fibre. 相似文献