A new method derived from the Z-scan by M.Sheik-baJiae et al.was employed to measure the thermooptic coefficient of materials effectively.A simple rule to determine the sign and magnitude of thermooptic coefficient an...A new method derived from the Z-scan by M.Sheik-baJiae et al.was employed to measure the thermooptic coefficient of materials effectively.A simple rule to determine the sign and magnitude of thermooptic coefficient and laser beam waist radius was obtained.展开更多
Applicability of guided mode resonant structures to tunable optical filtering and sensing is demonstrated using nematic liquid crystals. As a sensor, a minimum refractive index detectivity of 10^-5 is demonstrated whi...Applicability of guided mode resonant structures to tunable optical filtering and sensing is demonstrated using nematic liquid crystals. As a sensor, a minimum refractive index detectivity of 10^-5 is demonstrated while as a tunable filter, tunability range of few tens of nanometers with 2-nm bandwidth is presented. The optimum design is achieved by maximizing the evanescent field region in the analyte which maximizes the overlap integral. The device can be operated in reflection or transmission modes at normal incidence. It can also be operated at a single wavelength by measuring the angular profile of the light beam.展开更多
The experimental results of a 2x2 integrated thermooptic Mach-Zehnder interferometer(MZI)switch based on multimode interference(MMI)couplers are reported.The insertion loss(IL)is 3.40 dB,the polarization dependent los...The experimental results of a 2x2 integrated thermooptic Mach-Zehnder interferometer(MZI)switch based on multimode interference(MMI)couplers are reported.The insertion loss(IL)is 3.40 dB,the polarization dependent loss is 0.47 dB,the extinction ratio(ER)at bar state and cross state is 32.01 dB and 16.42 dB respectively,the response time is less than 3 ms,and the power consumption is 658 mW.Regarding the asymmetry of extinction ratio at bar state and cross state,theoretical analysis is first presented.The coupling ratio of the two MMI couplers deviates from 50׃50 but the deviation is nearly the same,which is decided by good uniformity of semiconductor planar lightwave circuit(PLC)process.This property affects the extinction ratio at bar state and cross state in different mechanisms.Adding a metal electrode on the waveguide affects its effective index and analysis based on experimental results is given.The increment of waveguide effective index is in the order of 2x10^(-4).展开更多
Modulation arms with different widths are introduced to Mach-Zehnder interferometers （MZIs） to obtain improved performance. Theoretical analysis and numerical simulation have shown that when tile widths of tile two ...Modulation arms with different widths are introduced to Mach-Zehnder interferometers （MZIs） to obtain improved performance. Theoretical analysis and numerical simulation have shown that when tile widths of tile two arms are properly designed to achieve an inherent mπ/2 （m is an odd integer） optical phase difference between the arms, the asymmetric MZI presents higher modulation speed. Furthermore, the carrier-absorption induced divergence of insertion losses in silicon-on-insulator （SOI） based MZI optical switches can be obviously improved.展开更多
Optical switches are desired in telecom and datacom as an upgrade to electrical ones for lower power consumption and expenses while improving bandwidth and network transparency.Compact,integrated optical switches are ...Optical switches are desired in telecom and datacom as an upgrade to electrical ones for lower power consumption and expenses while improving bandwidth and network transparency.Compact,integrated optical switches are attractive thanks to their scalability,readiness for mass production,and robustness against mechanical disturbances.The basic unit relies mostly on a microring resonator or a MachZehnder interferometer for binary“bar”and“cross”switching.Such single-mode structures are often wavelength/polarization dependent,sensitive to phase errors and loss-prone.Furthermore,when they are cascaded to a network,the number of control units grows quickly with the port count,causing high complexity in electronic wiring and drive circuit integration.Herein,we propose a new switching method by thermo-optic waveguide lens.Essentially,this multimode waveguide forms a square law medium by a pair of heater electrodes and focuses light within a chip by robust 1×1 imaging.A 1×24 basic switch is demonstrated with 32 electrodes and only two are biased at a time for a chosen output.By two-level cascading,the switch expands to 576 ports and only four electrodes are needed for one path.The chips are fabricated on wafer scale in a low-budget laboratory without resorting to foundries.Yet,the performance goes beyond state of the art for low insertion loss,low wavelength dependence and low polarization dependence.This work provides an original,alternative,and practical route to construct large-scale optical switches,enabling broad applications in telecom,datacom and photonic computing.展开更多
We present the results of performance modeling of a diode-pumped solid-state HiLASE laser designed for use in inertial fusion energy power plants. The main amplifier concept is based on a He-gas-cooled multi-slab arch...We present the results of performance modeling of a diode-pumped solid-state HiLASE laser designed for use in inertial fusion energy power plants. The main amplifier concept is based on a He-gas-cooled multi-slab architecture similar to that employed in Mercury laser system. Our modeling quantifies the reduction of thermally induced phase aberrations and average depolarization in Yb3+:YAG slabs by a combination of helium cryogenic cooling and properly designed(doping/width) cladding materials.展开更多
文摘A new method derived from the Z-scan by M.Sheik-baJiae et al.was employed to measure the thermooptic coefficient of materials effectively.A simple rule to determine the sign and magnitude of thermooptic coefficient and laser beam waist radius was obtained.
基金supported by the Ministry of Scienceunder Tashtiot Project
文摘Applicability of guided mode resonant structures to tunable optical filtering and sensing is demonstrated using nematic liquid crystals. As a sensor, a minimum refractive index detectivity of 10^-5 is demonstrated while as a tunable filter, tunability range of few tens of nanometers with 2-nm bandwidth is presented. The optimum design is achieved by maximizing the evanescent field region in the analyte which maximizes the overlap integral. The device can be operated in reflection or transmission modes at normal incidence. It can also be operated at a single wavelength by measuring the angular profile of the light beam.
文摘The experimental results of a 2x2 integrated thermooptic Mach-Zehnder interferometer(MZI)switch based on multimode interference(MMI)couplers are reported.The insertion loss(IL)is 3.40 dB,the polarization dependent loss is 0.47 dB,the extinction ratio(ER)at bar state and cross state is 32.01 dB and 16.42 dB respectively,the response time is less than 3 ms,and the power consumption is 658 mW.Regarding the asymmetry of extinction ratio at bar state and cross state,theoretical analysis is first presented.The coupling ratio of the two MMI couplers deviates from 50׃50 but the deviation is nearly the same,which is decided by good uniformity of semiconductor planar lightwave circuit(PLC)process.This property affects the extinction ratio at bar state and cross state in different mechanisms.Adding a metal electrode on the waveguide affects its effective index and analysis based on experimental results is given.The increment of waveguide effective index is in the order of 2x10^(-4).
基金Supported by the National Natural Science Foundation of China under Grant No 60336010, and the Special Funds for Major State Basic Research Project of China under Grant No G20000366.
文摘Modulation arms with different widths are introduced to Mach-Zehnder interferometers （MZIs） to obtain improved performance. Theoretical analysis and numerical simulation have shown that when tile widths of tile two arms are properly designed to achieve an inherent mπ/2 （m is an odd integer） optical phase difference between the arms, the asymmetric MZI presents higher modulation speed. Furthermore, the carrier-absorption induced divergence of insertion losses in silicon-on-insulator （SOI） based MZI optical switches can be obviously improved.
文摘Optical switches are desired in telecom and datacom as an upgrade to electrical ones for lower power consumption and expenses while improving bandwidth and network transparency.Compact,integrated optical switches are attractive thanks to their scalability,readiness for mass production,and robustness against mechanical disturbances.The basic unit relies mostly on a microring resonator or a MachZehnder interferometer for binary“bar”and“cross”switching.Such single-mode structures are often wavelength/polarization dependent,sensitive to phase errors and loss-prone.Furthermore,when they are cascaded to a network,the number of control units grows quickly with the port count,causing high complexity in electronic wiring and drive circuit integration.Herein,we propose a new switching method by thermo-optic waveguide lens.Essentially,this multimode waveguide forms a square law medium by a pair of heater electrodes and focuses light within a chip by robust 1×1 imaging.A 1×24 basic switch is demonstrated with 32 electrodes and only two are biased at a time for a chosen output.By two-level cascading,the switch expands to 576 ports and only four electrodes are needed for one path.The chips are fabricated on wafer scale in a low-budget laboratory without resorting to foundries.Yet,the performance goes beyond state of the art for low insertion loss,low wavelength dependence and low polarization dependence.This work provides an original,alternative,and practical route to construct large-scale optical switches,enabling broad applications in telecom,datacom and photonic computing.
基金the support of the Czech Republic’s Ministry of Education, Youth and Sports to the HiLASE (CZ.1.05/2.1.00/01.0027), DPSSLasers (CZ.1.07/2.3.00/ 20.0143), and Postdok (CZ.1.07/2.3.00/30.0057) projects, co-financed by the European Regional Development Fund. This research was supported by grant RVO 68407700
文摘We present the results of performance modeling of a diode-pumped solid-state HiLASE laser designed for use in inertial fusion energy power plants. The main amplifier concept is based on a He-gas-cooled multi-slab architecture similar to that employed in Mercury laser system. Our modeling quantifies the reduction of thermally induced phase aberrations and average depolarization in Yb3+:YAG slabs by a combination of helium cryogenic cooling and properly designed(doping/width) cladding materials.
