Using Nd:YAG second harmonic pulse (100 ps), the optical storage properties of two novel polyesters, poly [4'-bis (N, N-oxyethylene) imino-4-nitroazobenzene succinyl] and poly [2'-chloro-4'-bis (N, N-oxyet...Using Nd:YAG second harmonic pulse (100 ps), the optical storage properties of two novel polyesters, poly [4'-bis (N, N-oxyethylene) imino-4-nitroazobenzene succinyl] and poly [2'-chloro-4'-bis (N, N-oxyethylene) imino-4-nitroazobenzene succinyl] have been studied by multiwave mixing. The high-order diffractions of the orientation gratings induced by anisotropy via the reorientation of nitroazobenzene groups and optical information storage with long-term stability have been realized by multiwave mixing in their films. Up to 3rd order forward diffraction was detected in two wave mixing, while up to 4th order backward diffraction was observed in degenerated four wave mixing. The recording mechanism was explained by the trans-cis-trans isomerization cycles of azobenzene groups. The isomerization of these azobenzene groups probably undergoes with inversion mechanism under the experimental conditions. The information recorded in these films has been kept for more than 6 months.展开更多
Based on a modified coupled wave theory of Kogelnik, we have studied the diffraction of an ultrashort pulsed beam with an arbitrary polarization state from a volume holographic grating in photorefractive LiNbO3 crysta...Based on a modified coupled wave theory of Kogelnik, we have studied the diffraction of an ultrashort pulsed beam with an arbitrary polarization state from a volume holographic grating in photorefractive LiNbO3 crystals. The results indicate that the diffracted intensity distributions in the spectral and temporal domains and the diffraction efficiency of the grating are both changed by the polarization state and spectral bandwidth of the input pulsed beam. A method is given of choosing the grating parameters and input conditions to obtain a large variation range of the spectral bandwidth of the diffracted pulsed beam with an appropriate diffraction efficiency. Our study presents a possibility of using a volume holographic grating recorded in anisotropic materials to shape a broadband ultrashort pulsed beam by modulating its polarization state.展开更多
The possibilities of manufacturing of diffraction optical elements (DOE), using the “Caroline 15 PE” plasma-etching machine were considered. It is established that at thickness of chromic mask of 100 nm the plasma-c...The possibilities of manufacturing of diffraction optical elements (DOE), using the “Caroline 15 PE” plasma-etching machine were considered. It is established that at thickness of chromic mask of 100 nm the plasma-chemical etching (PCE) method reaches depth of surface micro-profile to 1.4 μm on optical glass. It allows increasing the diffraction efficiency of DOE to 0.3 - 0.35 on the second order of diffraction.展开更多
An intensity-modulated, fiber Bragg grating （FBG） sensor system based on radio-frequency （RF） signal measurement is presented. The RF signal is generated at a photodetector by two modulated optical signals reflect...An intensity-modulated, fiber Bragg grating （FBG） sensor system based on radio-frequency （RF） signal measurement is presented. The RF signal is generated at a photodetector by two modulated optical signals reflected from the sensing FBG and a reference one. Bragg wavelength shift of the sensing FBG changes intensity of the RF signal by changing phase difference between the two optical signals, with temperature effect being compensated automatically by the reference FBG, Strain measurement with a maximum sensitivity of -0.34 μV/με has been achieved.展开更多
Optical spectrometer of the Guillermo Haro astrophysical observatory (Mexico) realizes investigations in the visible and near-infrared range 350 - 800 nm and exploits mechanically removable traditional static diffract...Optical spectrometer of the Guillermo Haro astrophysical observatory (Mexico) realizes investigations in the visible and near-infrared range 350 - 800 nm and exploits mechanically removable traditional static diffraction gratings as dispersive elements. There is a set of the static gratings with slit-densities 150 - 600 lines/mm and optical apertures 9 cm × 9 cm that provide the first order spectral resolution from 0.8 to 3.2 A/pixel, respectively. However, the needed mechanical manipulations, namely, replacing the static diffraction gratings with various resolutions and following recalibration of spectrometer within studying even the same object are practically inconvenient and lead to wasting rather expensive observation time. We suggest exploiting an acousto-optical cell, i.e. the dynamic diffraction grating tunable electronically, as dispersive element in that spectrometer. Involving the acousto-optical technique, which can potentially provide electronic control over the spectral resolution and the range of observations, leads to eliminating the abovementioned demerits and improving the efficiency of analysis.展开更多
A novel semiconductor laser which can achieve mode-hop-free tuning is proposed.The device consists of an etched diffraction grating(EDG) as a dispersive element to provide the mode selection function and an active wav...A novel semiconductor laser which can achieve mode-hop-free tuning is proposed.The device consists of an etched diffraction grating(EDG) as a dispersive element to provide the mode selection function and an active waveguide to provide optical gain for the laser.The slab waveguide region of the EDG contains a tuning section covered by an electrode to inject a tuning current,and thus changes the refractive index.Mode-hop-free tuning is achieved by specially designing the shape of the tuning section,so that the tuning rate of the central wavelength reflected by the EDG and the tuning rate of the resonant wavelength of the laser cavity are equal.An optimized tuning section shape is designed to obtain the largest tuning range within a limited current range.Numerical simulation is presented to demonstrate the mode-hop-free tuning operation.展开更多
Optical surface scattering analyses based on diffractive optics (DO) are typically applied to one surface;however, there is a need for simulating surface scattering losses for devices having many surface interactions ...Optical surface scattering analyses based on diffractive optics (DO) are typically applied to one surface;however, there is a need for simulating surface scattering losses for devices having many surface interactions such as light pipes. Light pipes are often simulated with geometric optics (GO) using ray tracing, where surface scattering is driven by the surface slope distribution. In the DO case, surface scattering analyses depend on the spatial frequency distribution and amplitude as well as wavelength, with the sinusoidal grating as a fundamental basis. A better understanding of the link, or transition, between DO and GO scattering domains would be helpful for efficiently incorporating scattering loss analyses into ray trace simulations. A formula for the root-mean-square (rms) scattered angle width of a sinusoidal reflection grating that depends only on the surface rms slope is derived from the nonparaxial scalar diffraction theory, thereby linking it to GO. The scatter angle’s mean and rms width are evaluated over a range of grating amplitudes and periods using scalar theory and full vector simulations from the COMSOL® wave optic module for a sinusoidal reflection grating. The conditions under which the diffraction-based solution closely approximates the GO solution, as predicted by the rms slope, are identified. Close agreement is shown between the DO and GO solutions for the same surface rms slope scattering loss due to angular filtering near the critical angle of a total internal reflection (TIR) glass-to-air interface.展开更多
The cascadability of uniform fibre Bragg grating for 40 Gbit/s return to zero on-off keying to non-return to zero on-off keying format conversion has been shown using OptSim simulation program. The main idea of this a...The cascadability of uniform fibre Bragg grating for 40 Gbit/s return to zero on-off keying to non-return to zero on-off keying format conversion has been shown using OptSim simulation program. The main idea of this approach is use of specially designed uniform fibre Bragg grating with appropriate transfer function for shaping of 40 Gbit/s return to zero on-off keying optical spectrum. Error free performance is achieved after four cascades of uniform fibre Bragg grating with different reflectivity values.展开更多
This review focuses on recent developments in additive manufacturing(AM)of precision optical devices,particularly devices consisting of components with critical features at the micro-and nanoscale.These include,but ar...This review focuses on recent developments in additive manufacturing(AM)of precision optical devices,particularly devices consisting of components with critical features at the micro-and nanoscale.These include,but are not limited to,microlenses,diffractive optical elements,and photonic devices.However,optical devices with large-size lenses and mirrors are not specifically included as this technology has not demonstrated feasibilities in that category.The review is roughly divided into two slightly separated topics,the first on meso-and microoptics and the second on optics with nanoscale features.Although AM of precision optics is still in its infancy with many unanswered questions,the references cited on this exciting topic demonstrate an enabling technology with almost unlimited possibilities.There are many high quality reviews of AM processes of non-optical components,hence they are not the focus of this review.The main purpose of this review is to start a conversion on optical fabrication based on information about 3D AM methods that has been made available to date,with an ultimate long-term goal of establishing new optical manufacturing methods that are low cost and highly precise with extreme flexibility.展开更多
In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Seve...In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Several even splitters in the terahertz region were designed and one of the silicon-based beam splitters designed to separate one incident beam into four emergent beams has total efficiency up to 92.23 %. Zero-order diffraction efficiency was reduced to less than 0.192 % and the error of uniformity decreased to 6.51 9 10-6. These results break the limitation of even beam splitting based on the traditional scalar theory. In addition, the effects of the incident angle, wavelength, as well as the polarizing angle on the diffraction efficiency and uniformity were also investigated.展开更多
文摘Using Nd:YAG second harmonic pulse (100 ps), the optical storage properties of two novel polyesters, poly [4'-bis (N, N-oxyethylene) imino-4-nitroazobenzene succinyl] and poly [2'-chloro-4'-bis (N, N-oxyethylene) imino-4-nitroazobenzene succinyl] have been studied by multiwave mixing. The high-order diffractions of the orientation gratings induced by anisotropy via the reorientation of nitroazobenzene groups and optical information storage with long-term stability have been realized by multiwave mixing in their films. Up to 3rd order forward diffraction was detected in two wave mixing, while up to 4th order backward diffraction was observed in degenerated four wave mixing. The recording mechanism was explained by the trans-cis-trans isomerization cycles of azobenzene groups. The isomerization of these azobenzene groups probably undergoes with inversion mechanism under the experimental conditions. The information recorded in these films has been kept for more than 6 months.
基金Project supported by the State Key Development Program for Basic Research of China （Grant No 2002CCA03500）, and the National Natural Science Foundation of China （Grant No 60177016）.
文摘Based on a modified coupled wave theory of Kogelnik, we have studied the diffraction of an ultrashort pulsed beam with an arbitrary polarization state from a volume holographic grating in photorefractive LiNbO3 crystals. The results indicate that the diffracted intensity distributions in the spectral and temporal domains and the diffraction efficiency of the grating are both changed by the polarization state and spectral bandwidth of the input pulsed beam. A method is given of choosing the grating parameters and input conditions to obtain a large variation range of the spectral bandwidth of the diffracted pulsed beam with an appropriate diffraction efficiency. Our study presents a possibility of using a volume holographic grating recorded in anisotropic materials to shape a broadband ultrashort pulsed beam by modulating its polarization state.
文摘The possibilities of manufacturing of diffraction optical elements (DOE), using the “Caroline 15 PE” plasma-etching machine were considered. It is established that at thickness of chromic mask of 100 nm the plasma-chemical etching (PCE) method reaches depth of surface micro-profile to 1.4 μm on optical glass. It allows increasing the diffraction efficiency of DOE to 0.3 - 0.35 on the second order of diffraction.
基金supported by the National Natural Science Foundation of China under Grant No. 60807021.
文摘An intensity-modulated, fiber Bragg grating （FBG） sensor system based on radio-frequency （RF） signal measurement is presented. The RF signal is generated at a photodetector by two modulated optical signals reflected from the sensing FBG and a reference one. Bragg wavelength shift of the sensing FBG changes intensity of the RF signal by changing phase difference between the two optical signals, with temperature effect being compensated automatically by the reference FBG, Strain measurement with a maximum sensitivity of -0.34 μV/με has been achieved.
基金This work was co-supported by the National Basic Research Program of China （973 Program） under Grant No. 2010CB327804, the National Natural Science Foundation of China under Grant No. 60807021, and the Natural Science Foundation of Zhejiang Province, China under Grant No. RI080087. The author thanks all the collaborators and students who contributed to this work.
文摘Optical spectrometer of the Guillermo Haro astrophysical observatory (Mexico) realizes investigations in the visible and near-infrared range 350 - 800 nm and exploits mechanically removable traditional static diffraction gratings as dispersive elements. There is a set of the static gratings with slit-densities 150 - 600 lines/mm and optical apertures 9 cm × 9 cm that provide the first order spectral resolution from 0.8 to 3.2 A/pixel, respectively. However, the needed mechanical manipulations, namely, replacing the static diffraction gratings with various resolutions and following recalibration of spectrometer within studying even the same object are practically inconvenient and lead to wasting rather expensive observation time. We suggest exploiting an acousto-optical cell, i.e. the dynamic diffraction grating tunable electronically, as dispersive element in that spectrometer. Involving the acousto-optical technique, which can potentially provide electronic control over the spectral resolution and the range of observations, leads to eliminating the abovementioned demerits and improving the efficiency of analysis.
基金supported by the National Natural Science Foundation of China (No 60788403)the Fundamental Research Funds for the Central Universities of China
文摘A novel semiconductor laser which can achieve mode-hop-free tuning is proposed.The device consists of an etched diffraction grating(EDG) as a dispersive element to provide the mode selection function and an active waveguide to provide optical gain for the laser.The slab waveguide region of the EDG contains a tuning section covered by an electrode to inject a tuning current,and thus changes the refractive index.Mode-hop-free tuning is achieved by specially designing the shape of the tuning section,so that the tuning rate of the central wavelength reflected by the EDG and the tuning rate of the resonant wavelength of the laser cavity are equal.An optimized tuning section shape is designed to obtain the largest tuning range within a limited current range.Numerical simulation is presented to demonstrate the mode-hop-free tuning operation.
文摘Optical surface scattering analyses based on diffractive optics (DO) are typically applied to one surface;however, there is a need for simulating surface scattering losses for devices having many surface interactions such as light pipes. Light pipes are often simulated with geometric optics (GO) using ray tracing, where surface scattering is driven by the surface slope distribution. In the DO case, surface scattering analyses depend on the spatial frequency distribution and amplitude as well as wavelength, with the sinusoidal grating as a fundamental basis. A better understanding of the link, or transition, between DO and GO scattering domains would be helpful for efficiently incorporating scattering loss analyses into ray trace simulations. A formula for the root-mean-square (rms) scattered angle width of a sinusoidal reflection grating that depends only on the surface rms slope is derived from the nonparaxial scalar diffraction theory, thereby linking it to GO. The scatter angle’s mean and rms width are evaluated over a range of grating amplitudes and periods using scalar theory and full vector simulations from the COMSOL® wave optic module for a sinusoidal reflection grating. The conditions under which the diffraction-based solution closely approximates the GO solution, as predicted by the rms slope, are identified. Close agreement is shown between the DO and GO solutions for the same surface rms slope scattering loss due to angular filtering near the critical angle of a total internal reflection (TIR) glass-to-air interface.
文摘The cascadability of uniform fibre Bragg grating for 40 Gbit/s return to zero on-off keying to non-return to zero on-off keying format conversion has been shown using OptSim simulation program. The main idea of this approach is use of specially designed uniform fibre Bragg grating with appropriate transfer function for shaping of 40 Gbit/s return to zero on-off keying optical spectrum. Error free performance is achieved after four cascades of uniform fibre Bragg grating with different reflectivity values.
文摘This review focuses on recent developments in additive manufacturing(AM)of precision optical devices,particularly devices consisting of components with critical features at the micro-and nanoscale.These include,but are not limited to,microlenses,diffractive optical elements,and photonic devices.However,optical devices with large-size lenses and mirrors are not specifically included as this technology has not demonstrated feasibilities in that category.The review is roughly divided into two slightly separated topics,the first on meso-and microoptics and the second on optics with nanoscale features.Although AM of precision optics is still in its infancy with many unanswered questions,the references cited on this exciting topic demonstrate an enabling technology with almost unlimited possibilities.There are many high quality reviews of AM processes of non-optical components,hence they are not the focus of this review.The main purpose of this review is to start a conversion on optical fabrication based on information about 3D AM methods that has been made available to date,with an ultimate long-term goal of establishing new optical manufacturing methods that are low cost and highly precise with extreme flexibility.
基金supported by grants from the Natural Science Foundation of China(Nos.61275167,60878036and 60178023)the Basic Research Project of Shenzhen(Nos.JCYJ20130329103020637,JCYJ20120613112628842,JCYJ20140418095735591 and JC201005280533A)
文摘In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Several even splitters in the terahertz region were designed and one of the silicon-based beam splitters designed to separate one incident beam into four emergent beams has total efficiency up to 92.23 %. Zero-order diffraction efficiency was reduced to less than 0.192 % and the error of uniformity decreased to 6.51 9 10-6. These results break the limitation of even beam splitting based on the traditional scalar theory. In addition, the effects of the incident angle, wavelength, as well as the polarizing angle on the diffraction efficiency and uniformity were also investigated.
