共查询到20条相似文献,搜索用时 31 毫秒
1.
According to the oblique incidence characteristics of thin film narrowband filter, the stack of 100 GHz DWDM four cavities angle-tuned thin film filter has been designed and optimized. The two polarization modes’ central wavelengths of the thin film filter can be centered at the same one in oblique incidence, and it has a stable tuning range of 20 nm without the phenomenon of polarization central wavelength separation. Using this kind of angle-tuned thin film filter and the polarization beam-splitters, the tuning range of the angle-tuned thin film filter can be further expanded due to the reason that it can transmit only the s-polarization light. In this paper we also developed a three-port bandpass tunable filter device with new structure, which tuning range can cover the whole C-band and its adjacent channel isolation degree is high. The experiments show that the three-port tunable filter has an effective tuning range of 33 nm, and its adjacent channel isolation degree is more than 35 dB. It has a bright application opportunity for its flexibility and effective performance. 相似文献
2.
Takaaki Kakitsuka Shinji Matsuo Seok–Hwan Jeong Toru Segawa Hiroshi Okamoto Yoshihiro Kawaguchi Yasuhiro Kondo Yuzo Yoshikuni Hiroyuki Suzuki 《Optical and Quantum Electronics》2006,38(12-14):1053-1060
We theoretically investigated a digitally tunable laser with a chirped ladder filter and a ring resonator to obtain a wide wavelength tuning range covering the whole C- or L- band. The clear relation between the tuning range and laser structure, especially the ladder filter, is described analytically. The introduction of a chirped structure into a ladder filter is effective in achieving both wide tunability and a stable lasing mode. A numerical simulation based on multimode rate equations shows that a tuning range of over 40 nm and a mode suppression ratio over 40 dB can be achieved by introducing a chirped ladder filter. 相似文献
3.
A filter based on a Mach-Zehnder interferometer (MZI) formed by cascading a pair of longperiod fiber gratings (LPFGs) written
by CO2 laser in a twisted single-mode fiber is proposed. The transmission spectrum of the filter is tuned by modifying the bending
curvature of the MZI, and thus wavelength tuning is achieved. And a tunable erbium-doped fiber (EDF) ring laser employing
the filter as a wavelengthselection component is experimentally demonstrated. The laser can be tuned continuously from 1573.05
to 1595.75 nm with a side-mode suppression ration of ∼50 dB over the total tuning range. 相似文献
4.
The study proposes a new structure to double the free-spectral range (FSR) of a micro-ring resonator filter using optical interference. The proposed structure adds an input light to the Add port of the conventional two-bus one-ring (TBOR) filter and adds a phase shifter to tuning the light. The FSR of the conventional TBOR filter can be doubled by the interference from the light field of the new input port. In the study, the effects of the output spectrum depending on the phase shift, coupling coefficient, and loss are discussed. The results show that the resonance wavelength changes by tuning of the phase shifter which increases the choice of wavelength. Meanwhile a flat pass band, a sharpness degree of edge rolloff, a high quality factor as high as 105 and a perfect extinction effect can be obtained by selecting a proper coupling coefficient. However loss can bring more crosstalk which should be decreased as more as possible. 相似文献
5.
W. Vanderbauwhede I. Moerman P. Van Daele P. Demeester 《Optical and Quantum Electronics》1996,28(5):583-590
We present the first demonstration ofE-field tuning of an InP-based grating-assisted vertical codirectional coupler filter with an InAIGaAs/InGaAsP MQW region in one of the waveguide cores. This filter exhibits 16 nm tuning by QW-electrorefraction, which is the highest value reported to our knowledge. The device has 3.2 nm bandwidth at 1568 nm for 1.6 mm interaction length, very low losses, good sidelobe suppression, high coupling efficiency and a modified polarization dependence. 相似文献
6.
胡宗福 《中国光学快报(英文版)》2004,2(1)
A new kind of tunable optical filter is proposed for DWDM optical communication application. It is based on cascaded polarization interference filter (PIF). The period and bandpass width of each PIF are decided by its optical path difference between o-ray and e-ray (OPDOE). When their OPDOEs are proportionately designed, the tuning range and bandpass width depend on OPDOE in the first and the last PIF, respectively. The tuning range, bandpass width and crosstalk are independent each other. The crosstalk is related to the OPDOE ratios among PIFs and can be suppressed by designing the PIF's 15 × 2N-7 × l1, 10 × 2N-6 × l1 and 2N-2 × l1 from the first to the last. This suggested OPDOEs can yield -50-dB crosstalk for any tuning range and bandpass width. The insert loss is less than i dB. As its loose alignment requirement, there is no limitation on cascaded PIF number. When 11 PIFs are cascaded, it can achieve 170-nm tuning range, -50-dB crosstalk, bandpass width applicable to 25-GHz channel spacing and 1 dB insert loss. 相似文献
7.
A. Baum D. Grebner W. Paa W. Triebel M. Larionov A. Giesen 《Applied physics. B, Lasers and optics》2005,81(8):1091-1096
We describe an arrangement for an Yb:YAG thin disk laser, which enables narrow bandwidth operation in single-frequency mode
at freely selectable wavelengths within the broad tuning range of the laser. This is facilitated by a combination of a double-stage
birefringent filter and an etalon inside the laser cavity. We investigate the wavelength selection characteristics of the
single elements as well as their combination. A simple procedure is implemented for a computer-based automation of wavelength
tuning. The reflectivity of the partially reflecting resonator mirror is optimised, and the laser pump power is adapted for
best tuning performance. Single-frequency emission is achieved in a frequency range of 9.75 THz (wavelength range 1020 nm
to 1055 nm). Each axial laser mode in this range can be selected individually. The axial mode separation of 0.47 GHz corresponds
to wavelength steps of 1.7 pm at 1030 nm.
PACS 42.55.Xi; 42.60.Fc; 42.60.Lh 相似文献
8.
We report the fabrication of a discretely tunable erbium-doped fiber ring laser with a novel scheme that can select ITU-T grids of 50-GHz spacing in both C and L bands. Wavelength selections of 273 channels are demonstrated with a signal to source spontaneous emission ratio of 60 dB/nm and excellent power flatness over 111-nm bandwidth. This was realized by incorporating both a solid Fabry–Pérot interferometer and a fiber Fabry–Pérot tunable filter into the ring laser. To our knowledge, our experimental result has the widest tuning range ever reported for a discretely tunable fiber laser with 50-GHz channel spacing that matches the ITU-T grids and is the first equipment that can operate in both C and L bands. PACS 42.55.Wd; 42.60.Da; 42.60.-v 相似文献
9.
Experimental investigation ofd Nd:YAG monolithic nonplanar ring lasers operated at 1123 nm wavelength is presented. Stable single-frequency 1123 nm laser output has been obtained with successful suppression of the strong 1064 nm radiation. Single-frequency output power of 1.25 W is demonstrated with a pump power of 3.98 W at 808 nm, which gives a slope efficiency of 39%. The laser frequency tuning range is over 3 GHz, and the average tuning rate with temperature is -2.6 GHz/ degrees C. A strong iodine absorption line can be covered within the laser frequency tuning range. 相似文献
10.
Birefringent filters can be used for tuning lasers, with some advantages over prisms, gratings and tilted etalons. In this paper the transmission characteristics of a new mixed birefringent filter are investigated. The term ‘mixed’ is used because both circular birefringence and linear birefringence have been utilized in the fabrication of this filter.It has a loss-less core, formed by a cascaded system of alternate rotators and retarders, and a linear polarizer at each end. The performance of this filter is better because of the more effective suppression of side peaks. Unlike previous birefringent filters, this one may be used inside a linear resonator. 相似文献
11.
We demonstrate double-cavity micromachined tunable filters with electrical actuations for both blue and red wavelength tuning.
Electrical actuations for both shifts can be achieved by combining electrostatic and electro-thermal actuations below and
above the breakdown voltage of p-n junctions in the micromachined cantilevers. The measured tuning range with the actuation
is 8 nm for both tuning sides and the micromachined filter with a cantilever length of 80 μm exhibits a switching time of
less than 115 μs for both turn-on and turn-off states. We also present the theoretical and measured temperature dependence
of fabricated micromachined filters at various cantilever lengths, which experimentally gives us a temperature dependence
of 0.14 nm/K for a cantilever length of 100 μm. 相似文献
12.
O’Connor M.V. Watson M.A. Shepherd D.P. Hanna D.C. 《Applied physics. B, Lasers and optics》2004,79(1):15-23
Design considerations are presented for birefringent filters suitable for use as tuning elements in synchronously pumped optical parametric oscillators. A particular design aspect that is important, since typical gains are rather high, is the adequate suppression of subsidiary transmission maxima, in order to maximize the tuning range. Results are presented on the performance of a picosecond synchronously pumped optical parametric oscillator based on periodically poled lithium niobate with an appropriately designed four-plate birefringent filter. PACS 42.65.Yj; 42.72.Ai 相似文献
13.
Hongsik Jung 《Fiber and Integrated Optics》2013,32(4):294-304
Abstract ?olc-type wavelength filters have been demonstrated in a 52-mm long periodically poled titanium-diffused lithium niobate channel waveguide with a domain period of 16.6 μm. At room temperature, the center wavelength and the full-width at half maximum of the filter were about 1,272.49 nm and 0.23 nm, respectively. The nearest side-lobe is about 7 dB. New structures of flat-top bandpass filters and an optical add/drop multiplexer utilizing ?olc-type TE?TM mode converters are proposed for the first time. 相似文献
14.
A novel configuration of compound-cavity multi-wavelength Brillouin erbium fiber laser is proposed and experimentally demonstrated.
With an incident optical carrier power of 8 dBm, at least 14 lasing lines are obtained with a wavelength spacing of ∼0.08
nm. Stability and power uniformity of the multi-wave-length lasing are ensured by the flat hybrid gain of Brillouin and erbium,
the compound-cavity structure, and the four-wave mixing suppression using a long (10 km) single-mode fiber. A stable and frequency-switchable
microwave can be achieved by incorporating a fiber Bragg grating filter to select the desired nth-order Stokes wave and beating it with the optical carrier at a photodetector. In our experiment, the 1st-4th-order Stokes
waves are filtered respectively and hence a high-quality microwave with a switchable frequency from ∼10 to ∼40 GHz and a tuning
step of ∼10 GHz is achieved. The signal-to-noise ratio is measured to be >25 dB. 相似文献
15.
We have proposed channel drop filters based on a combination of Fabry-Perot (F-P) resonators in a two-dimensional photonic crystal with a triangular lattice of air holes. By tuning the separation, the radii of air holes between F-P resonators, and the length of two F-P resonators, we can selectively improve filter characteristics and obtain a forward-dropping efficiency of 95% and a backward-dropping efficiency of 90% at desired resonance frequencies. For the case where two F-P resonators are directly connected without separation, it forms a ring behavior and has a backward-dropping efficiency of 75% at resonance. Moreover, we investigate the dependence of optical bistability in one of the optimized resonators on initial frequency detunings. A switching speed of 2 ps is obtained. By decreasing the initial frequency detuning, overshoot on the switching-on power can be greatly suppressed. 相似文献
16.
P. P. Sahu 《Fiber and Integrated Optics》2013,32(1):24-34
Abstract A tunable add/drop filter based on Cascaded Mach Zehnder (CMZ) coupler using SiO2/silicon oxinitride (SiON) is presented with its mathematical model. The increase of filtered width (i.e., free spectral response) and lowering of crosstalk for this filter are optimized using its mathematical model with truncated binomial coupler distribution. The number of wavelength channels with 100 GHz (0.8 nm) channel spacing for 5-stage (M = 9, r = 2) truncated binomial CMZ filter with index contrast ~5% at ?20 dB crosstalk and the bending loss of 0.1 dB per MZ section are obtained as ~37 (free spectral range of 31 nm). It is seen that if during the fabrication process, waveguide core width w is increased or decreased by 0.1 μm (in percentage terms ~±6.6%), the crosstalk is slightly increased by ~7%. Thermal tuning for wavelength channels is achieved by thin film heater with low power thermooptic delay line structure which reduces the heating power by ~1.58 times in comparison to the conventional structure. 相似文献
17.
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19.
The laminar boundary layer separation flow over a two-dimensional bump controlled by synthetic jets is experimentally investigated in a water channel with hydrogen-bubble visualisation and particle image velocimetry (PIV) techniques. The two-dimensional synthetic jet is applied near the separation point. Two Reynolds numbers (Re = 700 and 1120) based on the bump height and free-stream velocity are adopted in this experiment, and seven different excitation frequencies at each Reynolds number are considered, focusing on the separation control as well as the vortex dynamics. The experimental results show that the optimal control can only be achieved within some excitation frequencies at both Reynolds numbers. However, beyond this range, further increasing the excitation frequency leads to an increase in the separation region. The proper orthogonal decomposition (POD) technique and vortex identification by swirling strength (Λci) are applied for the deeper analysis of the separated flow. The reconstructed Λci field by the first four POD modes is used and vortex lock-on phenomenon is observed. It is found that the negative synthetic jet vortex with clockwise rotation draws the separated wake shear layer as it is convected downstream, and then they syncretise together. Thus, the new vortex is induced and shedding downstream periodically. 相似文献