Carrier suppression in quadruple frequency modulation by cascaded optical external modulators for millimeter-wave generation

The optical carrier suppression in optical quadruple frequency modulation by cascaded external modulators is investigated theoretically and experimentally. Theoretical analysis demonstrates that the optical carrier suppression ratio is related with not only the initial phase difference of electrical signals applied on the two modulators, but also the optical phase shift between the two modulators. The maximum suppression ratio can be achieved when the total phase difference is equal to nπ＋π/2 （n = 1, 2,…）, which is verified by experiments. By properly controlling the total phase shift, 40-GHz millimeter-wave is generated by using a 10-GHz radio frequency （RF） source and the modulators.     

A coherent beam combination system based on double PZT phase modulators

A novel coherent beam combination system based on double piezoelectric ceramics transducer (PZT) phase modulators is presented and demonstrated for the first time. In this system, two different PZT phase modulators are used for high frequency phase modulation and low frequency phase control, respectively, while in previous demonstrated system, LiNbO₃ phase modulators are often employed. The inherent low insert loss and high laser-induced damage threshold of the PZT phase modulator makes the new proposed system more compact and stable. By the way, the experiment of coherent beam combination of two 5-W fiber laser beams based on double PZT phase modulators is done. In the experiment, the PZT phase modulator with 500-kHz frequency response point made in home is used for high frequency phase modulating and another one with 0～30-kHz linear frequency response range for phase controlling. When the phase control system is in the closed loop, the fringe contrast of far-field intensity pattern is improved to be more than 90 % from 5 % in open loop.     

极性反转结构电光波导调制器的频域响应分析

本文详细分析了具有极性反转电极结构电光调制器的响应特性，推导出器件输出端振幅和相位的频率响应的解析表达式，并给出相应的数值计算结果．     

偏置M-Z调制器构建2-bits电光模数转换相位编码方法的分析与模拟

为了降低电光相位编码器功率消耗和解决内部M Z调制器一致性要求高的问题,利用2个偏置M Z调制器构成了用于电光模数转换的2 bits电光相位编码器。理论分析了偏置M Z调制器实现2 bits电光相位编码的方法、特点和性能。仿真结果验证了采用偏置M Z调制器构成的2 bits相位编码方法可行性,并实现了对1 GHz模拟电信号的采样速率12 GSa/s模数转换。分析和仿真结果表明,采用该方法对调制器一致性要求低,对输入信号功率要求低于0.32 W。分析结果表明,调制器直流漂移不影响最低位量化结果,引起最高位量化结果的判决模糊低于3.8%。     

The generation of optical duobinary signal using electroabsorption modulator for optical access networks

We generate the duobinary signal by utilizing the intensity modulation characteristic of the electroabsorption modulator and the phase characteristic of phase shifter for the high-speed transmission system. In addition, compared to those commercial 10 Gbps OOK modulators, lower cost, better performances and easier integration can be achieved by using these duobinary modulators.     

Sequence of phase correction in multiconjugate adaptive optics

The way in which the sequence of phase correction impinges on performance in multiconjugate adaptive optics systems is described. When multiple phase modulators with different conjugate ranges are used, the conjugate images of the phase modulators in the atmosphere must be reimaged in the reverse order post focus, and adaptive phase correction applied in this sequence for perfect amplitude and phase cancellation. Performing the correction without relay optics results in residual amplitude and phase aberrations. It is shown, by Monte Carlo simulations of Fresnel propagation, that the effects of wave optical propagation become nonnegligible at visible wavelengths and for large air masses.     

Comparison of Volume and Integrated P-I-N Modulators in Millimeter Wave Range

Volume and based on surface oriented integrated p-i-n-structures modulators have demonstrated high efficiency in millimeter wave range as quasi-optical modulators and phase shifters. These structures possess high modulation and high-speed properties; sustain great EM powers. However, the modulation characteristics of p-i-n modulators of both mentioned types in millimeter wave range have not been investigated yet. Here, a comparison and criteria of volume and integrated based on Si surface oriented structure modulators in millimeter wave range are presented.     

Wideband optical phase modulator half-wave voltage measurement technique based on phase modulation optical link

We measured the half-wave voltage V_π of LiNbO₃ phase modulators in the broadband frequency range by analyzing the gain of phase modulation interference demodulation optical link. This is a new high practical value measurement method for half-wave voltage of LiNbO₃ phase modulators in wideband frequency range, and can accurately predict the nonlinear frequency characteristics of phase modulation optical link.     

采用接触式极化法研制有机聚合物电光光波导调制器

结合器件的整体结构考虑，对接触式极化方法和工艺进行了研究，基于接触式极化法，设计并制作了聚合物电光光波导相位和偏振调制器。通过测量器件的偏振调制特性，在1550nm光波波长下，获得了最大电光系数为llpm／V，电光相位调制器的半波电压为45V。     

Optical isolator using two tandem phase modulators

We propose and demonstrate an integrated optical isolator in InP using two phase modulators in series. The phase modulators are driven with a single-frequency signal in quadrature. Theoretically there is no effect on the forward signal, and the carrier of the backward signal can be eliminated, the energy distributed to other frequencies. We achieve a carrier isolation of 11?dB and an excess insertion loss of 2.3?dB. Such an isolator can be monolithically integrated with a laser without extra materials or magnetic fields.     

Tunable and reconfigurable microwave photonic filter based on cascaded modulation for multi-taps generation

In this paper, a theoretical analysis and experiment to obtain the tunable and reconfigurable microwave photonic filter is proposed. The sidebands generated by cascaded modulation serve as the multi-taps, and then the reconfigurability and tunability can be realized by adjusting the operating condition of intensity modulators and the optical phase shifting between modulators.     

Analyses for various doping structures of SOI-based optical phase modulator using free carrier dispersion effect

This paper highlights the study on various structure of silicon-on-insulator (SOI) optical phase modulators based on free carrier dispersion effect. The proposed modulators employ the forward biased P-I-N diode structure integrated in the waveguide and will be working at 1.55 μm optical telecommunications wavelength. Three kinds of structure are compared systematically where the p+ and n+ doping positions are varied. The modeling and characterization of the SOI phase modulators was carried out by 3D numerical simulation package. Our results show that the position of doping regions have a great influences to the device performance. It was discovered that the best structure in this work demonstrated modulation efficiency of 0.015 V cm with a length of 155 μm.     

Modulation masking produced by beating modulators.

This study examined whether "modulation masking" could be produced by temporal similarity of the probe and masker envelopes, even when the masker envelope did not contain a spectral component close to the probe frequency. Both masker and probe amplitude modulation were applied to a single 4-kHz sinusoidal or narrow-band noise carrier with a level of 70 dB SPL. The threshold for detecting 5-Hz probe modulation was affected by the presence of a pair of masker modulators beating at a 5-Hz rate (40 and 45 Hz, 50 and 55 Hz, or 60 and 65 Hz). The threshold was dependent on the phase of the probe modulation relative to the beat cycle of the masker modulators; the threshold elevation was greatest (12-15 dB for the sinusoidal carrier and 9-11 dB for the noise carrier, expressed as 20 log m) when the peak amplitude of the probe modulation coincided with a peak in the beat cycle. The maximum threshold elevation of the 5-Hz probe produced by the beating masker modulators was 7-12 dB greater than that produced by the individual components of the masker modulators. The threshold elevation produced by the beating masker modulators was 2-10 dB greater for 5-Hz probe modulation than for 3- or 7-Hz probe modulation. These results cannot be explained in terms of the spectra of the envelopes of the stimuli, as the beating masker modulators did not produce a 5-Hz component in the spectra of the envelopes. The threshold for detecting 5-Hz probe modulation in the presence of 5-Hz masker modulation varied with the relative phase of the probe and masker modulation. The pattern of results was similar to that found with the beating two-component modulators, except that thresholds were highest when the masker and probe were 180 degrees out of phase. The results are consistent with the idea that nonlinearities within the auditory system introduce distortion in the internal representation of the envelopes of the stimuli. In the case of two-component beating modulators, a weak component is introduced at the beat rate, and it has an amplitude minimum when the beat cycle is at its maximum. The results could be fitted well using two models, one based on the concept of a sliding temporal integrator and one based on the concept of a modulation filter bank.     

高局域性的可调硅基混合表面等离子体光相位调制器

设计和分析了一种可调硅基混合表面等离子体相位调制器.表面等离子体的引入打破了衍射极限的限制,使光场局域在一个纳米尺寸范围.该调制器的实现采用了两种原理:硅材料的等离子体色散效应以及聚合物的电光效应.由于器件结构的电容和寄生电阻较小,RC响应时间为3.77 ps,调制带宽大约100 GHz.当外加2.5V的驱动电压时,该...     

Silicon microring-based signal modulation for chip-scale optical interconnection

Electro-optic modulation plays a critical role in implementing space-, power- and spectrally efficient optical interconnection for high-capacity computing systems. Microring resonators exhibit a great potential to achieve compact, low power-consumption and high-speed modulators. In this paper, we briefly review our efforts on designing and analyzing the microring modulators. Three types of single-ring modulators are discussed, from device behavior to possible system impact. We then present two novel double-ring modulators in which a passive ring resonator is added, enabling higher operation speed and lower power consumption. We also describe an opportunity of introducing phase modulation data formats into the on-chip communication environment. In this paper, our emphasis is placed on linking the devices’ physics to their system performance and providing potential technical solutions to physical-layer challenges of optical interconnection.     

Effects of crystallographic orientation on electrooptic spatial light modulator amplitude and phase responses

The effects of crystallographic orientation on output amplitude and signal-dependent phase distortions in electrooptic spatial light modulators such as the PROM and PRIZ are described.     

Phase-locked laser coherent interference

A method of locking the relative phase to provide stable constructive or destructive interference between the phase-modulated sidebands from a pair of phase modulators is demonstrated. It is discussed theoretically for optimal fringe visibility related to the phase noise from faulty system. After phase locking using the phase modulating and lock-in technique,the drift of the relative phase is focalized around ±0.0016 rad and the fringe visibility is restricted to 2×10-4 .     

High-repetitive frequency millimeter-wave signal generation using multi-cascaded external modulators based on carrier suppression technique

We have numerically and experimentally investigated how to generate high-repetitive frequency millimeter (mm)-wave using multi-cascaded intensity modulators based on optical carrier suppression (OCS) scheme. We have found the rule how to generate the high-repetitive frequency mm-wave by adjusting the repetitive frequency of the radio-frequency (RF) signals and the phase relation between the RF signals on the intensity modulators. Based on this rule, we have experimentally demonstrated to generate over 80 GHz optical mm-wave.     

A simple image-reject mixer based on two parallel phase modulators

A simple photonic microwave image-reject mixer (IRM) using two parallel phase modulators is proposed. First, a photonic microwave mixer with phase shift ability is achieved using two parallel phase modulators (PMs), an optical bandpass filter, three polarization controllers, three polarization beam splitters and two balanced photodetectors. At the output of the mixer, two frequency downconverted signals with tunable frequency difference can be obtained. By adjusting the phase difference as 90° and utilizing an electrical 90° hybrid, the useless components can be eliminated, and the image reject operation is realized. The key advantage of the proposed scheme is the usage of PM, which avoid the DC bias shifting problem and make the system simple and stable. A simulation is performed to verify the proposed scheme, a relative ??90° or 90° phase shift can be obtained between the two output ports of the photonic microwave mixer, at the output of the IRM, 60 dB image-reject ratio is obtained.     

Analysis and optimization of integrated-optic travelling-wave modulators using periodic and non-periodic phase reversals

An analysis is given of phase-reversal electrode structures used for phase matching in travelling-wave integrated-optic phase modulators. Both modulus and argument of the phase shift are obtained; both are required for applications involving broadband excitation. Periodic and non-periodic lossy structures are treated and the advantage of non-periodic structures for wide-band operation is demonstrated. Optimum structure arrangements and upper bounds to phase shift and figure of merit are derived.