We present a novel mechanism,which is formed by periodically changing the radii of dielectric rods in the middle row of a photonic crystal, to control and stop light. Using the Bloch theory and coupled-mode theoryl th...We present a novel mechanism,which is formed by periodically changing the radii of dielectric rods in the middle row of a photonic crystal, to control and stop light. Using the Bloch theory and coupled-mode theoryl the dispersion characteristic of such a photonic crystal coupled cavity optical waveguide is obtained. We also theoretically demonstrate that the group velocity of a light pulse in this system can be modulated by dynamically changing the refractive index or radii of the selected dielectric rods, and the light stopping can be achieved.展开更多
A novel scheme was proposed to generate a millimeter-wave （MMW） optical pulse by combining pulse repetition rate multiplication （PRRM） technology and temporal Talbot effect （TTE）. A cascaded Mach- Zehnder interf...A novel scheme was proposed to generate a millimeter-wave （MMW） optical pulse by combining pulse repetition rate multiplication （PRRM） technology and temporal Talbot effect （TTE）. A cascaded Mach- Zehnder interferometer （MZI） lattice was used for PRRM, and a linearly chirped fiber grating （LCFG） was used as TTE. The basic principle was analyzed by using a Gaussian input short pulse and its characteristics were discussed by numerical simulation. It is shown that the proposed scheme is feasible for MMW signal generation and has potential merits for practical application of radio over fiber （ROF） technology.展开更多
An actively mode-locked laser with tunable repetition rate is proposed and experimentally demonstrated based on a programmable electrical pattern generator. By changing the repetition rate of the electrical patterns a...An actively mode-locked laser with tunable repetition rate is proposed and experimentally demonstrated based on a programmable electrical pattern generator. By changing the repetition rate of the electrical patterns applied on the in-cavity modulator, the repetition rate of the output optical pulse sequences changes accordingly while the pulse width of the optical pulse train remains almost constant. In other words, the output ultra-short pulse train has a tunable duty cycle. In a proof-of-principle experiment, optical pulses with repetition rates of 10, 5, 2.5 and 1.25 GHz are obtained by adjusting the electrical pattern applied on the in-cavity modulator while their pulse widths remain almost unchanged.展开更多
In two-dimensional （2D） time-spreading/wavelength-hopping optical code division multiple access （OCDMA） systems, employing less coherent broadband optical pulse sources allows lower electrical operating rate and b...In two-dimensional （2D） time-spreading/wavelength-hopping optical code division multiple access （OCDMA） systems, employing less coherent broadband optical pulse sources allows lower electrical operating rate and better system performance. An optical gate based scheme for generating weakly coherent （approximately incoherent） broadband optical pulses was proposed and experimentally demonstrated. In this scheme, the terahertz optical asymmetric demultiplexer, together with a coherent narrowband control pulse source, turns an incoherent broadband continuous-wave （CW） light source into the required pulse source.展开更多
A novel scheme is proposed to transform an ultra-short optical pulse to a millimeter-wave frequencymodulated pulse by using the cascaded all-pass cavities （APCs）. The envelope waveform of the generated pulse train i...A novel scheme is proposed to transform an ultra-short optical pulse to a millimeter-wave frequencymodulated pulse by using the cascaded all-pass cavities （APCs）. The envelope waveform of the generated pulse train is calculated, showing effective improvement by APC cascading. The extinction ratio is analyzed with different input pulses, different cavity reflectivities, and different cascading numbers. It is shown that the cascading does not introduce much effect on the extinction ratio. Two designs by using Gires-Tournois cavity and waveguide ring resonators are proposed to realize the cascaded APC.展开更多
基金supported by the National Natural Science Foundation of China(No.10874128)
文摘We present a novel mechanism,which is formed by periodically changing the radii of dielectric rods in the middle row of a photonic crystal, to control and stop light. Using the Bloch theory and coupled-mode theoryl the dispersion characteristic of such a photonic crystal coupled cavity optical waveguide is obtained. We also theoretically demonstrate that the group velocity of a light pulse in this system can be modulated by dynamically changing the refractive index or radii of the selected dielectric rods, and the light stopping can be achieved.
文摘A novel scheme was proposed to generate a millimeter-wave （MMW） optical pulse by combining pulse repetition rate multiplication （PRRM） technology and temporal Talbot effect （TTE）. A cascaded Mach- Zehnder interferometer （MZI） lattice was used for PRRM, and a linearly chirped fiber grating （LCFG） was used as TTE. The basic principle was analyzed by using a Gaussian input short pulse and its characteristics were discussed by numerical simulation. It is shown that the proposed scheme is feasible for MMW signal generation and has potential merits for practical application of radio over fiber （ROF） technology.
基金supported by the National Natural Science Foundation of China (No.60607008)the National "863" Program of China (No.2007AA01Z271)
文摘An actively mode-locked laser with tunable repetition rate is proposed and experimentally demonstrated based on a programmable electrical pattern generator. By changing the repetition rate of the electrical patterns applied on the in-cavity modulator, the repetition rate of the output optical pulse sequences changes accordingly while the pulse width of the optical pulse train remains almost constant. In other words, the output ultra-short pulse train has a tunable duty cycle. In a proof-of-principle experiment, optical pulses with repetition rates of 10, 5, 2.5 and 1.25 GHz are obtained by adjusting the electrical pattern applied on the in-cavity modulator while their pulse widths remain almost unchanged.
文摘In two-dimensional （2D） time-spreading/wavelength-hopping optical code division multiple access （OCDMA） systems, employing less coherent broadband optical pulse sources allows lower electrical operating rate and better system performance. An optical gate based scheme for generating weakly coherent （approximately incoherent） broadband optical pulses was proposed and experimentally demonstrated. In this scheme, the terahertz optical asymmetric demultiplexer, together with a coherent narrowband control pulse source, turns an incoherent broadband continuous-wave （CW） light source into the required pulse source.
基金supported by the National Natural Science Foundation of China under Grant No.60871067
文摘A novel scheme is proposed to transform an ultra-short optical pulse to a millimeter-wave frequencymodulated pulse by using the cascaded all-pass cavities （APCs）. The envelope waveform of the generated pulse train is calculated, showing effective improvement by APC cascading. The extinction ratio is analyzed with different input pulses, different cavity reflectivities, and different cascading numbers. It is shown that the cascading does not introduce much effect on the extinction ratio. Two designs by using Gires-Tournois cavity and waveguide ring resonators are proposed to realize the cascaded APC.
