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1.
Half-wave retarders are primarily used in rotating the plane of polarization of polarized light. These retarders usually exhibit strong wavelength dependence. In this paper, the design and characteristics of an achromatic half-wave plate, formed by a cascaded system of birefringent plates, have been studied. Pancharatnam proposed a combination of three retarders in series and discussed the possibility of fabricating reasonably good achromatic quarter-wave plate with a suitable combination of their retardance. The system studied here is similar in construction to Pancharatnam configuration and behaves as an achromatic half-wave plate over a wide spectral range. The proposed configuration exhibits a maximum variation of only about ±1.4 degree over the entire wavelength range of 500–750 nm. In our analysis we have used Jones matrix formalism for the derivation of the general expression for the equivalent retardation and the azimuth of the combination. 相似文献
2.
M. Emam-Ismail 《Optics Communications》2010,283(22):4536-4540
This paper presents retardation calculations for achromatic and apochromatic half and quarter wave retarders of gypsum based birefringent crystal. The calculations indicate that an achromatic wave plates can be obtained by combining gypsum crystal with KDP, ADP, MgF2, sapphire and calcite birefringent crystals. The residual variation percentages of retardations as a function of wavelength for gypsum/KDP, gypsum/ADP, gypsum/MgF2, gypsum/sapphire and gypsum/calcite were found to be ± 1.7%, ± 3%, ± 12.2%, ± 12.0% and ± 7.2%, respectively. To reduce the spectral variation of retardations, a third layer (apochromatic) of birefringet material is added to the aforementioned achromatic wave plates. The proposed apochromatic wave plates are gypsum/KDP/quartz, gypsum/ADP/quartz, MgF2/ADP/gypsum, MgF2/KDP/gypsum and gypsum/sapphire/MgF2. The addition of a third layer has reduced spectral residual variation percentages of retardations of the aforementioned apochromatic designs to ± 0.27, ± 0.33, ± 0.3, ± 0.17 and ± 0.45, respectively. 相似文献
3.
Noriaki Onodera Kenichiro Tsuji Masaki Oiwa Syunsuke Minami Masatoshi Saruwatari 《Optical Review》2009,16(1):22-25
Less than 100ps, polarization-independent switching operation of an active birefringent optical fiber loop filter using 1.3
μm control optical pulses as well as a 1.3 μm semiconductor optical amplifier (SOA) has been demonstrated. In the proposed
SOA-based active birefringent filter operating at 1.55 μm wavelength, 1.3 μm SOA is employed to control the polarization-mode
dispersion in the loop part. By injecting 1.3 μm ps gain-switched optical control pulses into the SOA, 1.5 μm input signals
can be switched from the transmission port to the reflection port with less than 100 ps rise time. 相似文献
4.
Tunable diode-laser absorption of CO2 near 2.7 μm incorporating wavelength modulation spectroscopy with second-harmonic detection (WMS-2f) is used to provide a
new sensor for sensitive and accurate measurement of the temperature behind reflected shock waves in a shock-tube. The temperature
is inferred from the ratio of 2f signals for two selected absorption transitions, at 3633.08 and 3645.56 cm−1, belonging to the ν
1+ν
3 combination vibrational band of CO2 near 2.7 μm. The modulation depths of 0.078 and 0.063 cm−1 are optimized for the target conditions of the shock-heated gases (P∼1–2 atm, T∼800–1600 K). The sensor is designed to achieve a high sensitivity to the temperature and a low sensitivity to cold boundary-layer
effects and any changes in gas pressure or composition. The fixed-wavelength WMS-2f sensor is tested for temperature and CO2 concentration measurements in a heated static cell (600–1200 K) and in non-reactive shock-tube experiments (900–1700 K) using
CO2–Ar mixtures. The relatively large CO2 absorption strength near 2.7 μm and the use of a WMS-2f strategy minimizes noise and enables measurements with lower concentration,
higher accuracy, better sensitivity and improved signal-to-noise ratio (SNR) relative to earlier work, using transitions in
the 1.5 and 2.0 μm CO2 combination bands. The standard deviation of the measured temperature histories behind reflected shock waves is less than 0.5%.
The temperature sensor is also demonstrated in reactive shock-tube experiments of n-heptane oxidation. Seeding of relatively
inert CO2 in the initial fuel-oxidizer mixture is utilized to enable measurements of the pre-ignition temperature profiles. To our
knowledge, this work represents the first application of wavelength modulation spectroscopy to this new class of diode lasers
near 2.7 μm. 相似文献
5.
This study develops a non-destructive measurement system for determining the thickness and refractive indices of birefringent optical wave plates. Compared to previous methods presented in the literature, the proposed metrology system provides the ability to measure the thickness of the birefringent optical plate in high-precision. The results show that for a commercially available birefringent optical wave plate with refractive indices of ne=1.5518, n0=1.5427 and a thickness of 452.1428 μm, the experimentally determined value for the error in the wave plate thickness measurement is just 0.046 μm. The measurement resolution of the proposed system exceeds that of the interferometer hardware itself. The proposed method provides a simple yet highly accurate means of measuring the principal optical parameters of birefringent glass wave plates. 相似文献
6.
Terahertz achromatic quarter-wave plate 总被引:3,自引:0,他引:3
Phase retarders usually present a strong frequency dependence. We discuss the design and characterization of a terahertz achromatic quarter-wave plate. This wave plate is made from six birefringent quartz plates precisely designed and stacked together. Phase retardation has been measured over the whole terahertz range by terahertz polarimetry. This achromatic wave plate demonstrates a huge frequency bandwidth (upsilonmax/upsilonmin approximately 7), and therefore can be applied to terahertz time domain spectroscopy and polarimetry. 相似文献
7.
M. S. Gaponenko I. A. Denisov V. E. Kisel A. M. Malyarevich A. A. Zhilin A. A. Onushchenko N. V. Kuleshov K. V. Yumashev 《Applied physics. B, Lasers and optics》2008,93(4):787-791
Glass doped with PbS quantum dots is presented as a saturable absorber (SA) for a passive Q-switching of a diode-pumped 1.9 μm Tm:KYW laser. Output pulses with energy of 44 μJ at a repetition rate of 2.5 kHz with
an average output power of 110 mW were obtained. The Q-switching conversion efficiency was 33%. The absorption saturation intensity of the glass doped with PbS quantum dots with
a mean radius of 5.2 nm at a wavelength of 2 μm was measured to be 1.5 MW/cm2. 相似文献
8.
Y.-G. Han 《Applied physics. B, Lasers and optics》2009,95(2):383-387
We propose a novel and simple scheme for a temperature-insensitive strain measurement by using a birefringent interferometer
configured by a polarization-maintaining photonic crystal fiber (PM-PCF). The wavelength-dependent periodic transmission in
a birefringent interferometer can be achieved by using a PM-PCF between two linear polarizers. Since the PM-PCF is composed
of a single material, such as silica, the peak wavelength shift with temperature variation can be negligible because of the
small amount of the birefringence change of the PM-PCF with temperature change. The measured temperature sensitivity is −0.3 pm/°C.
However, the peak wavelength can be changed by strain because the peak wavelength shift is directly proportion to strain change.
The strain sensitivity is measured to be 1.3 pm/με in a strain range from 0 to 1600 με. The measurement resolution of the
strain is estimated to be 2.1 με. The proposed scheme has advantages of simple structure and low loss without a Sagnac loop,
temperature insensitivity, ease installation, and short length of a sensing probe compared with a conventional PMF-based Sagnac
loop interferometer. 相似文献
9.
M. P. Frolov Yu. V. Korostelin V. I. Kozlovsky V. V. Mislavsky Yu. P. Podmar’kov Ya. K. Skasyrsky A. A. Voronov 《Journal of Russian Laser Research》2011,32(6):528-536
We realized laser generation on a Fe2+:ZnTe crystal for first time. The crystal was pumped at room temperature by 40 ns pulses of an Er:YAG laser operating at a
wavelength of 2.94 μm in the Q-switching mode. The output energy of the Fe2+:ZnTe laser was 0.18 mJ at a slope efficiency of 2.4% with respect to absorbed pumping energy. We achieved tuning of the Fe2+:ZnTe laser generation wavelength within the range of 4.35–5.45 μm using a prism-dispersion cavity. 相似文献
10.
Liu L. Loh N. H. Tay B. Y. Tor S. B. Yin H. Q. Qu X. H. 《Applied Physics A: Materials Science & Processing》2011,103(4):1145-1151
Micro powder injection molding (μPIM) has been developed as a potential technique for mass production of microcomponents in microsystems due to its shaping
complexity at low cost, in which sintering is a crucial step to dictate the final properties of the microcomponents. In this
paper, final-stage sintering behavior of 316L stainless steel microsize structures prepared by μPIM, φ100 μm and φ60 μm, respectively, was studied. The effect of size reduction in the regime of micrometers on the density of various microsize
structures was investigated. Sintering kinetics of the microsize structures of φ100 μm and φ60 μm were studied based on particle level sintering models. It is found that the microsize structures of φ60 μm had higher density than the microsize structures of φ100 μm given the same sintering condition. The results indicate that size reduction in the regime of micrometers facilitated
densification of microsize structures. The grain growth mechanism of microsize structures varied with size. Whereas the grain
growth of the microsize structures of φ100 μm is governed by surface-diffusion-controlled pore drag, the grain growth of the microsize structures of φ60 μm is controlled by boundary diffusion. During densification, the microsize structures, φ100 μm and φ60 μm, are both controlled by lattice diffusion. The corresponding activation energies are reported in the paper. 相似文献
11.
A c-cut Tm:YAP laser which operated at 1.94 or 1.99 μm is reported in detail. The maximum output power was 20.4 and 19.8 W at
the wavelength around 1.99 and 1.94 μm, corresponding to the slope efficiency of 34.3 and 31.5%, respectively. For 1.94 μm
operation, with an F-P etalon inserted in the cavity, the output central wavelength was stable around 1.94 μm with about 0.15
nm linewidth. The beam quality factor M
2 was measured to be ∼1.8 for 1.99 μm and ∼1.9 for 1.94 μm. 相似文献
12.
P. Hariharan 《Optics & Laser Technology》2002,34(7):8557-511
Apochromatic retarders can be constructed by using a combination of three plates of different birefringent materials with properly chosen thicknesses. However, when dealing with a broad wavelength range, their performance depends very much on the materials chosen. A procedure is presented for optimizing the choice of materials for such a broad-band retarder. 相似文献
13.
J. P. Noblanc 《Applied Physics A: Materials Science & Processing》1977,13(3):211-223
Both low attenuation silica optical fibers with peak transmission in the wavelength regions of 0.85 μm, and 1.05 μm, and improved
lasers at both wavelengths are now available.
In this review paper, the principal components for emission, modulation and detection are described. The characteristics of
both semiconductor lasers, made of GaAs and related compounds, emitting at 0.85 μm or 1.05 μm and high neodymium-content lasers
are discussed. For modulation, current modulation of GaAs lasers and external electro-optic modulation are considered. Concerning
detection, the realisation of Si photodetectors suitable at 0.85 μm and the new photodetectors at 1.05 μm from Ga1−x
In
x
As are reviewed. 相似文献
14.
M. L. Hamilton R. Peverall G. A. D. Ritchie L. J. Thornton J. H. van Helden 《Applied physics. B, Lasers and optics》2009,97(3):715-722
We have demonstrated the production of ∼1.9 μm near-infrared radiation by using difference frequency generation within a 5%
MgO doped PPLN crystal by coupling ∼735 nm radiation from a tunable external cavity diode laser with relatively high powered
532 nm radiation from both Nd:YVO3 and Nd:YAG lasers. The radiation produced is of low power, ∼15 μW, and was used in conjunction with the sensitivity enhancing
techniques of wavelength modulation spectroscopy (WMS) and cavity enhanced absorption spectroscopy (CEAS). Experiments were
carried out on rotationally resolved transitions in the combination bands of NH3 and CO2 in the 1.9 μm region. An α
min value of 3.6×10−6 cm−1 Hz−1/2 was achieved for WMS measurements on CO2. A comparable α
min value of 2.2×10−6 cm−1 Hz−1/2 was achieved for NH3 using CEAS. The low NIR power indicates that despite the level of MgO doping quoted for the crystal, under prolonged exposure
photorefractive damage has occurred. 相似文献
15.
We report a ZGP OPO system capable of producing >6 W at a signal wavelength of 3.80 μm and an idler wavelength of 4.45 μm.
The pumping source is the Tm,Ho:GdVO4 laser operated at 2.049 μm with an M
2 of 1.07. The ZGP OPO generated a total combined output power of 6.1 W at signal wavelength and idler wavelength under pumping
power of 18.3 W, and an M
2 of 1.7 for OPO output was obtained. 相似文献
16.
Coherent terahertz radiation in a widely step-tunable range of 72.3–2706 μm (0.11–4.15 THz) has been generated in GaAs crystal
by difference-frequency generation using one CO2 laser with dual-wavelength output. The peak power of THz pulse reaches 35 W at the wavelength of 236.3 μm, which corresponds
to a pulse energy of 2.1 μJ. An average power of 10 μW has been achieved when working repetitively. This efficient terahertz
radiation source is more compact and widely tunable than other THz sources pumped by CO2 laser. 相似文献
17.
A new tensile strained InGaAs/InGaAlAs quantum well structure in the 1.3 μm wavelength region is proposed for high temperature
characteristics via quantum well band structure and optical gain calculations. To obtain such features, a tensile-strained
InGaAs/InGaAlAs quantum well structure, which emits light dominated by TM polarization, is considered. This proposed structure
has very high temperature characteristics (T
0 > 130 K) due to its high density of state at the first transition edge. This results clearly show the potential of tensile strained
quantum well structure usage for the high temperature operation of quantum well semiconductor lasers. 相似文献
18.
We have theoretically investigated the thermal characteristics of double-channel ridge–waveguide InGaAs/InAlAs/InP quantum
cascade lasers (QCLs) using a two-dimensional heat dissipation model. The temperature distribution, heat flow, and thermal
conductance (G
th) of QCLs were obtained through the thermal simulation. A thick electroplated Au around the laser ridges helps to improve
the heat dissipation from devices, being good enough to substitute the buried heterostructure (BH) by InP regrowth for epilayer-up
bonded lasers. The effects of the device geometry (i.e., ridge width and cavity length) on the G
th of QCLs were investigated. With 5 μm thick electroplated Au, the G
th is increased with the decrease of ridge width, indicating an improvement from G
th=177 W/K⋅cm2 at W=40 μm to G
th=301 W/K⋅cm2 at W=9 μm for 2 mm long lasers. For the 9 μm×2 mm epilayer-down bonded laser with 5 μm thick electroplated Au, the use of InP
contact layer leads to a further improvement of 13% in G
th, and it was totally raised by 45% corresponding to 436 W/K⋅cm2 compared to the epilayer-up bonded laser with InGaAs contact layer. It is found that the epilayer-down bonded 9 μm wide BH
laser with InP contact layer leads to the highest G
th=449 W/K⋅cm2. The theoretical results were also compared with available obtained experimentally data. 相似文献
19.
T. Calmano J. Siebenmorgen O. Hellmig K. Petermann G. Huber 《Applied physics. B, Lasers and optics》2010,100(1):131-135
Tracks of modified material were written with femtosecond-laser pulses in neodymium-doped YAG crystals. Due to a stress-induced
change of the refractive index, waveguiding beside the tracks and between two adjacent tracks with a distance of approximately
25 μm was observed. Loss measurements resulted in guiding losses of about 1.6 dB/cm for the double track waveguide. Spectroscopic
investigations of the 4
F
3/2→4
F
11/2 transmission lines of the neodymium ions, which are close to the modified region, revealed a small stress-induced red shift
of the lines. Laser oscillation of single-track waveguides and double-track waveguides was demonstrated with Ti:Sapphire laser
pumping at a wavelength of 808 nm. Best laser performance with about 1.3 W output power at 2.25 W launched pump power was
achieved using a double-track waveguide with a separation of 27 μm at an outcoupling transmission of 95%. 相似文献
20.
R. R. Vardanyan V. K. Dallakyan U. Kerst C. Boit 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2012,47(2):73-79
The different empirical models of light absorption in silicon by free charge carriers in near-infrared and infrared regions
are analyzed. An improved empirical model for free carrier absorption in silicon is developed. Results are obtained over the
wavelength range from 0.9 μm to 6 μm for n-type, and from 0.9 μm to 8 μm for p-type silicon. The new model is assessed ed by R
2 parameter and the sufficient fitting of the experimental data is presented. 相似文献