AIM： To evaluate the positive effects of blue-violet light filtering lenses in delaying myopia and relieving asthenopia in juveniles. METHODS： Sixty ametropia juveniles （aged range, 11-15y） were randomized into t...AIM： To evaluate the positive effects of blue-violet light filtering lenses in delaying myopia and relieving asthenopia in juveniles. METHODS： Sixty ametropia juveniles （aged range, 11-15y） were randomized into two groups： the test group （30 children, 60 eyes）, wearing blue-violet light filtering lenses; and the control group （30 children, 60 eyes）, wearing ordinary aspherical lenses. Baseline refractive power of the affected eyes and axial length of the two groups was recorded. After 1-year, the patients underwent contrast sensitivity （glare and non-glare under bright and dark conditions）, accommodation-related testing, asthenopia questionnaire assessment, and adverse reaction questionnaire assessment. RESULTS： After ly of wearing the filtering lenses, changes in refractive power and axial length were not significantly different between the two groups （P〉0.05）. Under bright conditions, the contrast sensitivities at low and medium- frequency grating （vision angles of 6.3, 4.0, and 2.5） with glare in the test group were significantly higher than in the control group （P〈0.05）, while the contrast sensitivity at low-frequency grating （vision angles of 6.3 and 4.0） in the absence of glare in the test group was higher than in the control group （P〈0.05）. Under glare and non-glare dark conditions, the contrast sensitivities of various frequencies in the test group did not show significant differences compared with those in the control group （P〉0.05）. In the test group, the amplitude of accommodation, accommodative lag, and accommodative sensitivity of patients wearing glasses for 6 and 12mo were significantly elevated （P〈0.05）, while the asthenopia gratings were significantly decreased （P〈0.05）. Nevertheless, in the control group,the amplitude of accommodation, accommodative lag, and accommodative sensitivity after 12mo were not significantly altered compared with baseline （P〉0.05）, and the asthenopia grating was not significantly decreased （P〉0.05）. In addition, after wearing glasses for 6 to 12mo, the asthenopia grating of patients in the test group decreased significantly compared with the control group （P〈0.05）. At 12mo, the constituent ratio of adverse reactions did not show significant difference between the two groups （P〉0.05）. CONCLUSION： A l-year follow-up reveal that compare with ordinary glasses, short-wavelength filtering lenses （blue/ violet-light filters） increase the low- and medium-frequency contrast sensitivity under bright conditions and improved accommodation. They effectively relieved asthenopia without severe adverse reactions, suggesting potential for clinical application. However, no significant advantages in terms of refractive power or axial length progression were found compared with ordinary aspheric lenses.展开更多
A wavelength filter with simple structure using multimode waveguide is proposed. The device uses mode conversion by a grating structure fabricated simultaneously with the multimode waveguide.
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...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%.展开更多
Sensitive detection of acetylene（C_2H_2） is performed by absorption spectroscopy and wavelength modulation spectroscopy（WMS） based on Fiber Fabry–Perot tunable filter（FFP-TF） at 1530.32 nm. After being calibrat...Sensitive detection of acetylene（C_2H_2） is performed by absorption spectroscopy and wavelength modulation spectroscopy（WMS） based on Fiber Fabry–Perot tunable filter（FFP-TF） at 1530.32 nm. After being calibrated by Fiber Bragg Grating（FBG）, FFP-TF is frequency-multiplexed and modulated at 20 Hz and 2.5 kHz respectively to achieve wavelength modulation. The linearity with 0.9907 fitting coefficient is obtained by measuring different concentrations in a 100 ppmv–400 ppmv range. Furthermore, the stability of the system is analyzed by detecting 50 ppmv and 100 ppmv standard gases for 2 h under room temperature and ambient pressure conditions respectively. The precision of 11 ppmv is achieved by calculating the standard deviation. Therefore, the measuring system of C_2H_2 detection can be applied in practical applications.展开更多
A system of unequal thickness interference filters with quarter wavelength stack which consists of a spacer surrounded by two multilayer stacks is designed, and the examples of the filter design are given. This kind o...A system of unequal thickness interference filters with quarter wavelength stack which consists of a spacer surrounded by two multilayer stacks is designed, and the examples of the filter design are given. This kind of filters are not only characterized by high-transparency, but also by high - reflection ,therefore , it is superior to the common equal thickness interference system with quarter wavelength . it is easier to control the manufacturing techniques of the new design as compared with that of interference filter of non- quarter wavelength.展开更多
The wavelength shift in fiber Bragg grating does not depend directly on the total light levels, losses in the connecting fibers and couplers, or source power. However, if the tunable Fabry-Perot filter is place on the...The wavelength shift in fiber Bragg grating does not depend directly on the total light levels, losses in the connecting fibers and couplers, or source power. However, if the tunable Fabry-Perot filter is place on the end of incident fiber, the detected time delay of modulation light is occurred due to the unmatch between the scanning time and light transmission time in the transmission fiber. Consequently, the detected peak wavelength shifts with the length of transmission fiber. Thus, the peak wavelength shift effect of Bragg reflective light transmitted in fiber with different fiber length can be obvious in the demodulator with a prepositive tunable Fabry-Perot filter. The experiment indicates the shift rates of 0.109 - 0.126 nm/km increase approximately linearly with the original peak wavelength of 1532.917 - 1560.300 nm at the fiber length of 0 - 6 km. To certify the consistency of measurement data, the criterion correction is introduced. By using the differential method of two fiber Bragg gratings with an optical path, the differential worth is compensated from the disturbance modulated by the time delay of fiber length.展开更多
In this paper, we design and fabricate a silicon integrated optical filter consisting of two cascaded micro-ring resonators and two straight waveguides. Two micro-heaters are fabricated on the top of two micro-rings r...In this paper, we design and fabricate a silicon integrated optical filter consisting of two cascaded micro-ring resonators and two straight waveguides. Two micro-heaters are fabricated on the top of two micro-rings respectively, which are employed to modulate the micro-rings to perform the function of a tunable optical filter by the thermo–optic effect. The static response test indicates that the extinction ratio and 3-d B bandwidth are 29.01 d B and 0.21 nm respectively, the dynamic response test indicates that the 10%–90% rise and 90%–10% fall time of the filter are 16 μs and 12 μs, respectively,which can meet the requirements of optical communication and information processing. Finally, the power consumption of the device is also characterized, and the total power consumption is about 9.43 m W/nm, which has been improved efficiently.展开更多
The design, production and characterization of tailored printable optical filters for visible optical communications are demonstrated. As result, the average color difference between the specified and the produced fil...The design, production and characterization of tailored printable optical filters for visible optical communications are demonstrated. As result, the average color difference between the specified and the produced filters is 32.6, quantified in terms of CIELAB coordinates.展开更多
Several high-performance and tunable erbium-doped fiber lasers are reviewed. They are constructed by using fiber Bragg gratings (FBGs) or short-wavelength-pass filters (SWPFs) as wavelength tunable components inside t...Several high-performance and tunable erbium-doped fiber lasers are reviewed. They are constructed by using fiber Bragg gratings (FBGs) or short-wavelength-pass filters (SWPFs) as wavelength tunable components inside the laser cavity. Broadband wavelength tuning range including C- and/or S-band was achieved, and tunable laser output with high slope efficiency, high side-mode suppression ratio was obtained. These fiber lasers can find vast applications in lightwave transmission, optical test instrument, fiber-optic gyros, spectroscopy, material processing, biophotonic imaging, and fiber sensor technologies.展开更多
The characteristics of reflected light of a 1-D guided-mode resonance filter(GMRF)are studied in this paper.A triple-layer GMRF is designed by using the finite difference time domain method under non-polarized light i...The characteristics of reflected light of a 1-D guided-mode resonance filter(GMRF)are studied in this paper.A triple-layer GMRF is designed by using the finite difference time domain method under non-polarized light illumination.Numerical results show that the reflectance spectra of TE and TM polarizations can be changed by altering the fill factor f of the GMRF.Moreover,by calculating the color of the reflected light with the chromaticity theory,we find that the color of reflected light becomes pure when f is 0.9.The results show that the color and polarization degree of the reflected light of a GMRF are tunable by altering the fill factor.展开更多
Based on the theory of four-port resonator filters, the characteristics of four kinds of filters with single race-track, dual race-track, rectangular and MMI resonators respectively were numerically simulated by utili...Based on the theory of four-port resonator filters, the characteristics of four kinds of filters with single race-track, dual race-track, rectangular and MMI resonators respectively were numerically simulated by utilizing two-dimensional FDTD method. The relationship between the number of cascade resonators and the filtering features was also analyzed. A kind of narrow-band filters with four cascade resonators implemented on GaAlAs/GaAs planar lightwave circuits were designed and fabricated. The measurement result shows that the half-width of such filters is about 10nm, which coincides well with the numeric computation.展开更多
基金Supported by Projects of Medical and Health Technology Development Program in Zhejiang Province(No.2011KYA020)
文摘AIM： To evaluate the positive effects of blue-violet light filtering lenses in delaying myopia and relieving asthenopia in juveniles. METHODS： Sixty ametropia juveniles （aged range, 11-15y） were randomized into two groups： the test group （30 children, 60 eyes）, wearing blue-violet light filtering lenses; and the control group （30 children, 60 eyes）, wearing ordinary aspherical lenses. Baseline refractive power of the affected eyes and axial length of the two groups was recorded. After 1-year, the patients underwent contrast sensitivity （glare and non-glare under bright and dark conditions）, accommodation-related testing, asthenopia questionnaire assessment, and adverse reaction questionnaire assessment. RESULTS： After ly of wearing the filtering lenses, changes in refractive power and axial length were not significantly different between the two groups （P〉0.05）. Under bright conditions, the contrast sensitivities at low and medium- frequency grating （vision angles of 6.3, 4.0, and 2.5） with glare in the test group were significantly higher than in the control group （P〈0.05）, while the contrast sensitivity at low-frequency grating （vision angles of 6.3 and 4.0） in the absence of glare in the test group was higher than in the control group （P〈0.05）. Under glare and non-glare dark conditions, the contrast sensitivities of various frequencies in the test group did not show significant differences compared with those in the control group （P〉0.05）. In the test group, the amplitude of accommodation, accommodative lag, and accommodative sensitivity of patients wearing glasses for 6 and 12mo were significantly elevated （P〈0.05）, while the asthenopia gratings were significantly decreased （P〈0.05）. Nevertheless, in the control group,the amplitude of accommodation, accommodative lag, and accommodative sensitivity after 12mo were not significantly altered compared with baseline （P〉0.05）, and the asthenopia grating was not significantly decreased （P〉0.05）. In addition, after wearing glasses for 6 to 12mo, the asthenopia grating of patients in the test group decreased significantly compared with the control group （P〈0.05）. At 12mo, the constituent ratio of adverse reactions did not show significant difference between the two groups （P〉0.05）. CONCLUSION： A l-year follow-up reveal that compare with ordinary glasses, short-wavelength filtering lenses （blue/ violet-light filters） increase the low- and medium-frequency contrast sensitivity under bright conditions and improved accommodation. They effectively relieved asthenopia without severe adverse reactions, suggesting potential for clinical application. However, no significant advantages in terms of refractive power or axial length progression were found compared with ordinary aspheric lenses.
文摘A wavelength filter with simple structure using multimode waveguide is proposed. The device uses mode conversion by a grating structure fabricated simultaneously with the multimode waveguide.
基金Project supported in part by the National Natural Science Foundation of China （Grant Nos 10474071, 60637010, 60671036 and 60278001） and Tianjin Applied Fundamental Research Project, China （07JCZDJC05900）.
文摘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%.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61172047 and 61071025)
文摘Sensitive detection of acetylene（C_2H_2） is performed by absorption spectroscopy and wavelength modulation spectroscopy（WMS） based on Fiber Fabry–Perot tunable filter（FFP-TF） at 1530.32 nm. After being calibrated by Fiber Bragg Grating（FBG）, FFP-TF is frequency-multiplexed and modulated at 20 Hz and 2.5 kHz respectively to achieve wavelength modulation. The linearity with 0.9907 fitting coefficient is obtained by measuring different concentrations in a 100 ppmv–400 ppmv range. Furthermore, the stability of the system is analyzed by detecting 50 ppmv and 100 ppmv standard gases for 2 h under room temperature and ambient pressure conditions respectively. The precision of 11 ppmv is achieved by calculating the standard deviation. Therefore, the measuring system of C_2H_2 detection can be applied in practical applications.
文摘A system of unequal thickness interference filters with quarter wavelength stack which consists of a spacer surrounded by two multilayer stacks is designed, and the examples of the filter design are given. This kind of filters are not only characterized by high-transparency, but also by high - reflection ,therefore , it is superior to the common equal thickness interference system with quarter wavelength . it is easier to control the manufacturing techniques of the new design as compared with that of interference filter of non- quarter wavelength.
文摘The wavelength shift in fiber Bragg grating does not depend directly on the total light levels, losses in the connecting fibers and couplers, or source power. However, if the tunable Fabry-Perot filter is place on the end of incident fiber, the detected time delay of modulation light is occurred due to the unmatch between the scanning time and light transmission time in the transmission fiber. Consequently, the detected peak wavelength shifts with the length of transmission fiber. Thus, the peak wavelength shift effect of Bragg reflective light transmitted in fiber with different fiber length can be obvious in the demodulator with a prepositive tunable Fabry-Perot filter. The experiment indicates the shift rates of 0.109 - 0.126 nm/km increase approximately linearly with the original peak wavelength of 1532.917 - 1560.300 nm at the fiber length of 0 - 6 km. To certify the consistency of measurement data, the criterion correction is introduced. By using the differential method of two fiber Bragg gratings with an optical path, the differential worth is compensated from the disturbance modulated by the time delay of fiber length.
基金Project supported by the National Natural Science Foundation of China(Grant No.61405082)the Fundamental Research Funds for the Central Universities
文摘In this paper, we design and fabricate a silicon integrated optical filter consisting of two cascaded micro-ring resonators and two straight waveguides. Two micro-heaters are fabricated on the top of two micro-rings respectively, which are employed to modulate the micro-rings to perform the function of a tunable optical filter by the thermo–optic effect. The static response test indicates that the extinction ratio and 3-d B bandwidth are 29.01 d B and 0.21 nm respectively, the dynamic response test indicates that the 10%–90% rise and 90%–10% fall time of the filter are 16 μs and 12 μs, respectively,which can meet the requirements of optical communication and information processing. Finally, the power consumption of the device is also characterized, and the total power consumption is about 9.43 m W/nm, which has been improved efficiently.
基金The financial support of“Scientific and technological collaboration Portugal/China 2010/2012.Proc.0 441.00”is gratefully acknowledged.
文摘The design, production and characterization of tailored printable optical filters for visible optical communications are demonstrated. As result, the average color difference between the specified and the produced filters is 32.6, quantified in terms of CIELAB coordinates.
文摘Several high-performance and tunable erbium-doped fiber lasers are reviewed. They are constructed by using fiber Bragg gratings (FBGs) or short-wavelength-pass filters (SWPFs) as wavelength tunable components inside the laser cavity. Broadband wavelength tuning range including C- and/or S-band was achieved, and tunable laser output with high slope efficiency, high side-mode suppression ratio was obtained. These fiber lasers can find vast applications in lightwave transmission, optical test instrument, fiber-optic gyros, spectroscopy, material processing, biophotonic imaging, and fiber sensor technologies.
基金National Natural Science Foundation of China (61605035)
文摘The characteristics of reflected light of a 1-D guided-mode resonance filter(GMRF)are studied in this paper.A triple-layer GMRF is designed by using the finite difference time domain method under non-polarized light illumination.Numerical results show that the reflectance spectra of TE and TM polarizations can be changed by altering the fill factor f of the GMRF.Moreover,by calculating the color of the reflected light with the chromaticity theory,we find that the color of reflected light becomes pure when f is 0.9.The results show that the color and polarization degree of the reflected light of a GMRF are tunable by altering the fill factor.
文摘Based on the theory of four-port resonator filters, the characteristics of four kinds of filters with single race-track, dual race-track, rectangular and MMI resonators respectively were numerically simulated by utilizing two-dimensional FDTD method. The relationship between the number of cascade resonators and the filtering features was also analyzed. A kind of narrow-band filters with four cascade resonators implemented on GaAlAs/GaAs planar lightwave circuits were designed and fabricated. The measurement result shows that the half-width of such filters is about 10nm, which coincides well with the numeric computation.
