We report optimal phase modulation based on enhanced electro–optic effects in a Mach–Zehnder(MZ) modulator constructed by AlGaAs/GaAs coupled double quantum well(CDQW) waveguides with optical gain. The net chang...We report optimal phase modulation based on enhanced electro–optic effects in a Mach–Zehnder(MZ) modulator constructed by AlGaAs/GaAs coupled double quantum well(CDQW) waveguides with optical gain. The net change of refractive indexes between two arms of the CDQW MZ modulator is derived by both the electronic polarization method and the normal-surface method. The numerical results show that very large refractive index change over 10^(-1) can be obtained, making the phase modulation in the CDQW MZ modulator very highly efficient. It is desirable and important that a very small voltage-length product for π phase shift, V_π× L_0= 0.0226 V · mm, is obtained by optimizing bias electric field and CDQW structural parameters, which is about seven times smaller than that in single quantum-well MZ modulators.These properties open an avenue for CDQW nanostructures in device applications such as electro–optical switches and phase modulators.展开更多
We theoretically analyze and experimentally demonstrate a method of generating equal-amplitude optical comb exploiting multi-frequency phase modulation. The theoretical analysis shows that 4n-1 equalamplitude spectral...We theoretically analyze and experimentally demonstrate a method of generating equal-amplitude optical comb exploiting multi-frequency phase modulation. The theoretical analysis shows that 4n-1 equalamplitude spectral lines can be obtained when the modulation signal comprises n frequency components including the fundamental frequency and the odd harmonic frequencies, and 2n+1 equal-amplitude spectral lines can be obtained when the modulation signal comprises n frequency components including the fundamental frequency and the even harmonic frequencies. Then, we numerically simulate the spectra of 5, 7, 9, and 11 equal-amplitude spectral lines, respectively, which are also obtained in experiments with frequency separation of 30 MHz and flatness of better than 0.3 dB.展开更多
This paper introduces a new modulation and direct detection scheme of optical phase shift keying (PSK) which is simple and practical in fiber optical communication. A phase modulator is used to modulate a continuous w...This paper introduces a new modulation and direct detection scheme of optical phase shift keying (PSK) which is simple and practical in fiber optical communication. A phase modulator is used to modulate a continuous wave (CW) laser source and return-to-zero (RZ) signal that is changed from the initial transmitting information is used to control a phase modulator to form a optical PSK signal. In the receiver terminal, just add a signal delayed a half of one bit to itself so that the initial information can be restored.展开更多
The cross gain modulation, the cross phase modulation and their recovery time in the SOAs with the various lengths were experimentally investigated. It was found that these values strongly depended on the device length.
We propose a novel silicon optical phase shifter structure based on heterogeneous strip-loaded waveguides on a photonic silicon on insulator(SOI) platform. The features of an etchless SOI layer and loaded strip would ...We propose a novel silicon optical phase shifter structure based on heterogeneous strip-loaded waveguides on a photonic silicon on insulator(SOI) platform. The features of an etchless SOI layer and loaded strip would enhance the performance and uniformity of silicon optical modulators on a large-scale wafer. We implemented the phase shifter by loading an amorphous silicon strip onto an SOI layer with a vertical PN diode structure. Compared to the conventional lateral PN phase shifter based on half-etched rib waveguides, this phase shifter shows a >1.5 times enhancement of modulation efficiency and provides >20 GHz high-speed operation.展开更多
We report all-optical mid-infrared phase and intensity modulators based on the photo-thermal effect in an acetylene-filled anti-resonant hollow-core fiber.Optical absorption of the control beam promotes the gas molecu...We report all-optical mid-infrared phase and intensity modulators based on the photo-thermal effect in an acetylene-filled anti-resonant hollow-core fiber.Optical absorption of the control beam promotes the gas molecules to a higher energy level,which induces localized heating through non-radiative relaxation and modulates the refractive index of the gas material and hence the accumulated phase of the signal beam propagating through the hollow-core fiber.By modulating the intensity of the control beam,the phase of the signal beam is modulated accordingly.By use of a 1.53μm near-infrared control beam,all-optical phase modulation up to 2.2πrad is experimentally demonstrated at the signal wavelength of 3.35μm.With the phase modulator placed in one arm of a Mach-Zehnder interferometer,intensity modulation with on-off ratio of 25 dB is achieved.The gas-filled hollow-core-fiber modulators could operate over an ultra-broad wavelength band from near-to mid-infrared and have promising application in mid-infrared photonic systems.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11474106)the Natural Science Foundation of Guangdong Province,China(Grant No.2016A030313439)the Science and Technology Program of Guangzhou City,China(Grant No.201707010403)
文摘We report optimal phase modulation based on enhanced electro–optic effects in a Mach–Zehnder(MZ) modulator constructed by AlGaAs/GaAs coupled double quantum well(CDQW) waveguides with optical gain. The net change of refractive indexes between two arms of the CDQW MZ modulator is derived by both the electronic polarization method and the normal-surface method. The numerical results show that very large refractive index change over 10^(-1) can be obtained, making the phase modulation in the CDQW MZ modulator very highly efficient. It is desirable and important that a very small voltage-length product for π phase shift, V_π× L_0= 0.0226 V · mm, is obtained by optimizing bias electric field and CDQW structural parameters, which is about seven times smaller than that in single quantum-well MZ modulators.These properties open an avenue for CDQW nanostructures in device applications such as electro–optical switches and phase modulators.
基金supported by the China Postdoctoral Science Foundation(No.20060400230)the Foundation for Innovation Talents by the Technology Ministry of Harbin(No.2006RFQXG025)
文摘We theoretically analyze and experimentally demonstrate a method of generating equal-amplitude optical comb exploiting multi-frequency phase modulation. The theoretical analysis shows that 4n-1 equalamplitude spectral lines can be obtained when the modulation signal comprises n frequency components including the fundamental frequency and the odd harmonic frequencies, and 2n+1 equal-amplitude spectral lines can be obtained when the modulation signal comprises n frequency components including the fundamental frequency and the even harmonic frequencies. Then, we numerically simulate the spectra of 5, 7, 9, and 11 equal-amplitude spectral lines, respectively, which are also obtained in experiments with frequency separation of 30 MHz and flatness of better than 0.3 dB.
文摘This paper introduces a new modulation and direct detection scheme of optical phase shift keying (PSK) which is simple and practical in fiber optical communication. A phase modulator is used to modulate a continuous wave (CW) laser source and return-to-zero (RZ) signal that is changed from the initial transmitting information is used to control a phase modulator to form a optical PSK signal. In the receiver terminal, just add a signal delayed a half of one bit to itself so that the initial information can be restored.
文摘The cross gain modulation, the cross phase modulation and their recovery time in the SOAs with the various lengths were experimentally investigated. It was found that these values strongly depended on the device length.
文摘We propose a novel silicon optical phase shifter structure based on heterogeneous strip-loaded waveguides on a photonic silicon on insulator(SOI) platform. The features of an etchless SOI layer and loaded strip would enhance the performance and uniformity of silicon optical modulators on a large-scale wafer. We implemented the phase shifter by loading an amorphous silicon strip onto an SOI layer with a vertical PN diode structure. Compared to the conventional lateral PN phase shifter based on half-etched rib waveguides, this phase shifter shows a >1.5 times enhancement of modulation efficiency and provides >20 GHz high-speed operation.
基金supported by the National Key Research and Development Program of China(2019YFB2203904)National Natural Science Foundation of China(61827820,62005233)+1 种基金the Shenzhen STIC Funding(RCBS20200714114819032)the Local Innovative and Research Teams Project of Guangdong Pear River Talents Program(2019BT02X105).
文摘We report all-optical mid-infrared phase and intensity modulators based on the photo-thermal effect in an acetylene-filled anti-resonant hollow-core fiber.Optical absorption of the control beam promotes the gas molecules to a higher energy level,which induces localized heating through non-radiative relaxation and modulates the refractive index of the gas material and hence the accumulated phase of the signal beam propagating through the hollow-core fiber.By modulating the intensity of the control beam,the phase of the signal beam is modulated accordingly.By use of a 1.53μm near-infrared control beam,all-optical phase modulation up to 2.2πrad is experimentally demonstrated at the signal wavelength of 3.35μm.With the phase modulator placed in one arm of a Mach-Zehnder interferometer,intensity modulation with on-off ratio of 25 dB is achieved.The gas-filled hollow-core-fiber modulators could operate over an ultra-broad wavelength band from near-to mid-infrared and have promising application in mid-infrared photonic systems.