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1.
By applying the microring resonator to the Mach-Zehnder (MZ) optical modulator and employing the super-linear phase change characteristic of the all-pass filter, the sublinear modulation curve of the conventional MZ modulator is highly linearized. With properly controlled power coupling between the microring and the arm of the MZ modulator, the third-order distortion can be suppressed. If the transmission coefficient is set between 0.25 and 0.42, the linearity range larger than 90% can be easily achieved. The maximum linearity range is even up to 99.5%.  相似文献   

2.
<正>On the silicon-on-insulator platform,an ultra compact temperature-insensitive modulator based on a cascaded microring assistant Mach-Zehnder interferometer is proposed and demonstrated with numerical simulation.According to the calculated results,the tolerated variation of ambient temperature can be as high as 134℃while the footprint of such a silicon modulator is only 340μm~2.  相似文献   

3.
We present a mechanically tunable broadband terahertz(THz) modulator based on the high-aligned Ni nanowire(NW)arrays. The modulator is a sandwich structure consisting of two polydimethylsiloxane layers and a central layer of highaligned Ni NW arrays. Our experimental measurements reveal the transmittance of THz wave can be effectively modulated by mechanical stretching. The NW density in arrays increases with the strain increasing, which induced an enhancement in the absorption of THz wave. When the strain increases from 0 to 6.5%, a linear relationship is observed for the variation of modulation depth(MD) of THz wave regarding the strain, and the modulated range is from 0 to 85% in a frequency range from 0.3 THz to 1.8 THz. Moreover, the detectable MD is about 15% regarding the 1% strain change resolution. This flexible Ni NW-based modulator can be promised many applications, such as remote strain sensing, and wearable devices.  相似文献   

4.
A complex-coefficient microwave photonic filter with continuous tunability is proposed and demonstrated,which has a compact structure and stable performance without splitting the optical path and tuning the polarization state. By only controlling the DC biases of the modulator, the amplitudes and the phases of the filter taps can both be tuned. The phase difference between the two filter taps covers a full 360° range from 10 GHz to 32 GHz. Frequency responses of the proposed filter are measured within 10–20 GHz with different center frequencies.  相似文献   

5.
An all-optical intensity modulator based on an optical microfiber coupler(OMC) is presented. The modulator works at 1550 nm wavelength and is modulated directly by heating the coupling region with 980 nm pump light injected through the coupling port of the OMC. The OMC is controlled to have at least a 30 mm long coupling region with diameter smaller than 8 μm, and the uniform waist region diameter is about 3 μm. This is helpful to ensure the optical modulation function based on the light induced thermal effect in the coupling region, while pump light is injected. The modulation response is measured to show good linearity when the 980 nm pump light has a lower intensity(with power below 2.5 mW), which proves that the OMC acts as an all-optical modulator.The bandwidth of the modulator can be at 0.2–50 kHz with the average power of the intensity-modulated pump light about 2 mW, which can be further improved by optimizing the design of the coupler. The demonstrated modulator may have potential value for the application in an all-optical integration system.  相似文献   

6.
The influence of applied electric fields on the absorption coefficient and subband distances in asymmetrical AlN/GaN coupled double quantum wells(CDQWs) has been investigated by solving Schrdinger and Poisson equations self-consistently.It is found that the absorption coefficient of the intersubband transition(ISBT) between the ground state and the third excited state(1odd 2even) can be equal to zero when the electric fields are applied in asymmetrical AlN/GaN CDQWs,which is related to applied electric fields induced symmetry recovery of these states.Meanwhile,the energy distances between 1odd 2even and 1even 2even subbands have different relationships from each other with the increase of applied electric fields due to the different polarization-induced potential drops between the left and the right wells.The results indicate that an electrical-optical modulator operated within the opto-communication wavelength range can be realized in spite of the strong polarization-induced electric fields in asymmetrical AlN/GaN CDQWs.  相似文献   

7.
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.  相似文献   

8.
When a high frequency tone is amplitude-modulated by another sine wave of low frequency,a distinctand predominating pitch corresponding to the frequency of modulating wave can be heard and it changeswhen the frequency of modulator is in turn modulated by a rectangula pulse.Thresholds of frequencydiscrimination of such an amplitude-modulator(f_(am))can be measured in guinea pigs by recording the slowcortical respones evoked by frequency-modulation of the modulator.f_(am)in relation to frequencies of thecarrier and modulator,to the depth of amplitude modulation,to the duration of the rectangular pulse and tosound intensity are systematically studied.The ability of guinea pig for discrimating the modulator seemsrather good.At optimal conditions the f_(am)of guinea pig amounts to 3—4 Hz,quite close to its frequencydifferential thresholds for pure tones.f_(am)in guinea pig and in human(measured by psychophysical method)are compared and mechanism of perception and discrimination of the modulator pitch is disc  相似文献   

9.
Optical microring resonators are extensively employed in a wide range of physical studies and applications due to the resonance enhancement property.Incorporating coupling control of a microring resonator is necessary in many scenarios,but modifications are essentially added to the resonator and impair the capability of optical enhancement.Here,we propose a flexible coupling structure based on adiabatic elimination that allows low-loss active coupling control without any modifications to the resonators.The self-coupling coefficient can be monotonically or non-monotonically controllable by the proposed coupler,potentially at a high speed.The characteristic of the coupler when implemented in silicon microring resonators is investigated in detail using substantiated analytical theory and experiments.This work provides a general method in coupling control while ensuring the resonance enhancement property,making active coupling control in a resonator-waveguide system feasible.  相似文献   

10.
The tracking precision of laser tracking system is affected by the angular resolution of quadrant avalanche photodiode. According to the detecting principle of quadrant avalanche photodiode, the light spot area, the optical intensity distribution, the non-uniformity of response, and the signal-to-noise ratio (SNR) that affect the linearity of the detector are studied. The light optical spot area and the optical intensity distribution can be adjusted through software. The non-uniformity of response and the SNR are influenced by the noise of the detector. Because the noise is affected by the optical intensity of the incident laser, it is difficult to obtain the law of the linearity caused by noise. When the light spot area and the optical intensity distribution are fixed, the other factors can be measured. With the detector scanned in raster scanning mode, the non-uniformity of response is measured at different SNRs. The linearity of detector is measured by a moving target that can reflect the illuminating laser to the detector in diffuse reflection mode. The nonlinear error of the linearity of detector can be minimized by increasing the SNR.  相似文献   

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