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Nonlinear Optics|110 Article(s)
Analysis of the performance of optical frequency comb based on recirculating frequency shifter influenced by an Er-doped fiber amplifier
Hao Tu, Lixia Xi, Xiaoguang Zhang, Xia Zhang, Jiachuan Lin, and Wan Meng
The factors that influence the generation of a high-quality optical frequency comb (OFC) based on a recirculating frequency shifter (RFS) due to the maximum output power and noise figure of Er-doped fiber amplifier (EDFA) are studied theoretically and experimentally. Based on the theoretical analysis, numerical simulations and experiments under different EDFA parameters have been carried out. The results show that the performance of the OFC based on a RFS can be improved effectively by optimizing the maximum output power and the noise figure of the EDFA. The factors that influence the generation of a high-quality optical frequency comb (OFC) based on a recirculating frequency shifter (RFS) due to the maximum output power and noise figure of Er-doped fiber amplifier (EDFA) are studied theoretically and experimentally. Based on the theoretical analysis, numerical simulations and experiments under different EDFA parameters have been carried out. The results show that the performance of the OFC based on a RFS can be improved effectively by optimizing the maximum output power and the noise figure of the EDFA.
Photonics Research
- Publication Date: Jul. 19, 2013
- Vol. 1, Issue 2, 02000088 (2013)
Imaging in focusing Kerr media using reverse propagation [Invited]
Alexandre Goy, and Demetri Psaltis
We present imaging experiments in focusing Kerr media using digital holography and digital reverse propagation (DRP) of the wave. For moderate power, the nonlinear DRP algorithm can be used to improve the quality of images over the linear DRP. We discuss the limits of the method at high power, the role of small-scale filaments, and the problem of time-dependent self-phase modulation. We present imaging experiments in focusing Kerr media using digital holography and digital reverse propagation (DRP) of the wave. For moderate power, the nonlinear DRP algorithm can be used to improve the quality of images over the linear DRP. We discuss the limits of the method at high power, the role of small-scale filaments, and the problem of time-dependent self-phase modulation.
Photonics Research
- Publication Date: Jul. 19, 2013
- Vol. 1, Issue 2, 02000096 (2013)
Modulation characteristics and microwave generation for AlGaInAs/InP microring lasers under four-wave mixing
Ling-Xiu Zou, Yong-Zhen Huang, Xiao-Meng Lv, Bo-Wen Liu, Heng Long, Yue-De Yang, Jin-Long Xiao, and and Yun Du
The dynamic characteristics are investigated for a microring laser with an external radius of 12 μm subject to external optical injection. Single-mode operation with a side mode suppression ratio of 33.4 dB is realized at a biasing current of 25 mA and a temperature of 290 K, and the corresponding small-signal modulation response is obtained with a resonance peak frequency of 7.5 GHz. Under the optical injection from a tunable laser, the improvements of the small-signal modulation response induced by four-wave mixing are observed for the microring laser, which shows an additional resonance peak around the frequency of the beat frequency between the lasing mode and the injecting light. Furthermore, optical generation of a microwave signal is realized by the light beating between the lasing mode and the injecting light measured by a high-speed photodetector and a spectrum analyzer. The dynamic characteristics are investigated for a microring laser with an external radius of 12 μm subject to external optical injection. Single-mode operation with a side mode suppression ratio of 33.4 dB is realized at a biasing current of 25 mA and a temperature of 290 K, and the corresponding small-signal modulation response is obtained with a resonance peak frequency of 7.5 GHz. Under the optical injection from a tunable laser, the improvements of the small-signal modulation response induced by four-wave mixing are observed for the microring laser, which shows an additional resonance peak around the frequency of the beat frequency between the lasing mode and the injecting light. Furthermore, optical generation of a microwave signal is realized by the light beating between the lasing mode and the injecting light measured by a high-speed photodetector and a spectrum analyzer.
Photonics Research
- Publication Date: Nov. 15, 2014
- Vol. 2, Issue 6, 06000177 (2014)
Conversion of out-of-phase to in-phase order in coupled laser arrays with second harmonics
Chene Tradonsky, Micha Nixon, Eitan Ronen, Vishwa Pal, Ronen Chriki, Asher A. Friesem, and Nir Davidson
A novel method for converting an array of out-of-phase lasers into one of in-phase lasers that can be tightly focused is presented. The method exploits second-harmonic generation and can be adapted for different laser arrays geometries. Experimental and calculated results, presented for negatively coupled lasers formed in a square, honeycomb, and triangular geometries are in good agreement. A novel method for converting an array of out-of-phase lasers into one of in-phase lasers that can be tightly focused is presented. The method exploits second-harmonic generation and can be adapted for different laser arrays geometries. Experimental and calculated results, presented for negatively coupled lasers formed in a square, honeycomb, and triangular geometries are in good agreement.
Photonics Research
- Publication Date: Apr. 10, 2015
- Vol. 3, Issue 3, 03000077 (2015)
False nonlinear effect in z-scan measurement based on semiconductor laser devices: theory and experiments
Hui Yan, and and Jingsong Wei
With the development of semiconductor technology, semiconductor laser devices and semiconductor laser pump solid-state laser devices have been widely applied in z-scan experiments. However, the feedback light-induced output instability of semiconductor laser devices can negatively affect the accurate testing of the nonlinear index. In this work, the influence of feedback light on z-scan measurement is analyzed. Then the calculated formula of feedback light-induced false nonlinear z-scan curves is theoretically derived and experimentally verified. Two methods are proposed to reduce or eliminate the feedback light-induced false nonlinear effect. One is the addition of an attenuator to the z-scan optical path, and the other is the addition of an opto-isolator unit to the z-scan setup. The experimental and theoretical results indicate that the feedback light-induced false nonlinear effect is markedly reduced and can even be ignored if appropriate parameters are chosen. Thus, theoretical and experimental methods of eliminating the negative effect of feedback light on z-scan measurement are useful for accurately obtaining the nonlinear index of a sample. With the development of semiconductor technology, semiconductor laser devices and semiconductor laser pump solid-state laser devices have been widely applied in z-scan experiments. However, the feedback light-induced output instability of semiconductor laser devices can negatively affect the accurate testing of the nonlinear index. In this work, the influence of feedback light on z-scan measurement is analyzed. Then the calculated formula of feedback light-induced false nonlinear z-scan curves is theoretically derived and experimentally verified. Two methods are proposed to reduce or eliminate the feedback light-induced false nonlinear effect. One is the addition of an attenuator to the z-scan optical path, and the other is the addition of an opto-isolator unit to the z-scan setup. The experimental and theoretical results indicate that the feedback light-induced false nonlinear effect is markedly reduced and can even be ignored if appropriate parameters are chosen. Thus, theoretical and experimental methods of eliminating the negative effect of feedback light on z-scan measurement are useful for accurately obtaining the nonlinear index of a sample.
Photonics Research
- Publication Date: Mar. 15, 2014
- Vol. 2, Issue 2, 02000051 (2014)
Direct detection of the transient superresolution effect of nonlinear saturation absorption thin films
Xinghao Zhang, and Jingsong Wei
Using a strong nonlinear saturation absorption effect is one technique for breaking through the diffraction limit. In this technique, formation of a dynamic and reversible optical pinhole channel and transient superresolution is critical. In this work, a pump–probe transient detection and observation–experimental setup is constructed to explore the formation process directly. A Ge2Sb2Te5 thin film with strong nonlinear saturation absorption is investigated. The dynamic evolution of the optical pinhole channel is detected and imaged, and the transient superresolution spot is directly captured experimentally. Results verify that the superresolution effect originates from the generation of an optical pinhole channel and that the formation of the optical pinhole channel is dynamic and reversible. A good method is provided for direct detection and observation of the transient process of the superresolution effect of nonlinear thin films. Using a strong nonlinear saturation absorption effect is one technique for breaking through the diffraction limit. In this technique, formation of a dynamic and reversible optical pinhole channel and transient superresolution is critical. In this work, a pump–probe transient detection and observation–experimental setup is constructed to explore the formation process directly. A Ge2Sb2Te5 thin film with strong nonlinear saturation absorption is investigated. The dynamic evolution of the optical pinhole channel is detected and imaged, and the transient superresolution spot is directly captured experimentally. Results verify that the superresolution effect originates from the generation of an optical pinhole channel and that the formation of the optical pinhole channel is dynamic and reversible. A good method is provided for direct detection and observation of the transient process of the superresolution effect of nonlinear thin films.
Photonics Research
- Publication Date: Apr. 29, 2015
- Vol. 3, Issue 4, 04000100 (2015)
Canonical logic units using bidirectional four-wave mixing in highly nonlinear fiber
W. C. Dong, J. Hou, Y. S. Kadhim, S. K. Tawfeeq, and X. L. Zhang
All-optical canonical logic units at 40 Gb/s using bidirectional four-wave mixing (FWM) in highly nonlinear fiber are proposed and experimentally demonstrated. Clear temporal waveforms and correct pattern streams are successfully observed in the experiment. This scheme can reduce the amount of nonlinear devices and enlarge the computing capacity compared with general ones. The numerical simulations are made to analyze the relationship between the FWM efficiency and the position of two interactional signals. All-optical canonical logic units at 40 Gb/s using bidirectional four-wave mixing (FWM) in highly nonlinear fiber are proposed and experimentally demonstrated. Clear temporal waveforms and correct pattern streams are successfully observed in the experiment. This scheme can reduce the amount of nonlinear devices and enlarge the computing capacity compared with general ones. The numerical simulations are made to analyze the relationship between the FWM efficiency and the position of two interactional signals.
Photonics Research
- Publication Date: Jun. 15, 2015
- Vol. 3, Issue 4, 04000164 (2015)
Hybrid silicon slotted photonic crystal waveguides: how does third order nonlinear performance scale with slow light
Junfei Xia, Samuel Serna, Weiwei Zhang, Laurent Vivien, and éric Cassan
We investigate in this paper the influence of slow light on the balance between the Kerr and two-photon absorption (TPA) processes in silicon slotted hybrid nonlinear waveguides. Three typical silicon photonic waveguide geometries are studied to estimate the influence of the light slow-down factor on the mode field overlap with the silicon region, as well as on the complex effective nonlinear susceptibility. It is found that slotted photonic crystal modes tend to focalize in their hollow core with increasing group index (nG) values. Considering a hybrid integration of nonlinear polymers in such slotted waveguides, a relative decrease of the TPA process by more factor of 2 is predicted from nG 10 to nG 50. As a whole, this work shows that the relative influence of TPA decreases for slotted waveguides operating in the slow light regime, making them a suitable platform for third-order nonlinear optics. We investigate in this paper the influence of slow light on the balance between the Kerr and two-photon absorption (TPA) processes in silicon slotted hybrid nonlinear waveguides. Three typical silicon photonic waveguide geometries are studied to estimate the influence of the light slow-down factor on the mode field overlap with the silicon region, as well as on the complex effective nonlinear susceptibility. It is found that slotted photonic crystal modes tend to focalize in their hollow core with increasing group index (nG) values. Considering a hybrid integration of nonlinear polymers in such slotted waveguides, a relative decrease of the TPA process by more factor of 2 is predicted from nG 10 to nG 50. As a whole, this work shows that the relative influence of TPA decreases for slotted waveguides operating in the slow light regime, making them a suitable platform for third-order nonlinear optics.
Photonics Research
- Publication Date: Nov. 15, 2016
- Vol. 4, Issue 6, 06000257 (2016)
Enhanced Kerr electro-optic nonlinearity and its application in controlling second-harmonic generation
Guang-Zhen Li, Yu-Ping Chen, Hao-Wei Jiang, and Xian-Feng Chen
We proposed a new scheme of controlling second-harmonic generation by enhanced Kerr electro-optic nonlinearity. We designed a structure that can implement the cascaded Pockels effect and second-harmonic generation simultaneously. The energy coupling between the fundamental lights of different polarizations led to a large nonlinear phase shift and, thus, an effective electro-optic nonlinear refractive index. The effective nonlinearity can be either positive or negative, causing the second-harmonic spectra to move toward the coupling center, which, in turn, offered us a way to measure the effective electro-optic nonlinear refractive index. The corresponding enhanced Kerr electro-optic nonlinearity is more than three orders of magnitude higher than the intrinsic value. These results open a door to manipulate the nonlinear phase by applying an external electric field instead of light intensity in noncentrosymmetric crystals. We proposed a new scheme of controlling second-harmonic generation by enhanced Kerr electro-optic nonlinearity. We designed a structure that can implement the cascaded Pockels effect and second-harmonic generation simultaneously. The energy coupling between the fundamental lights of different polarizations led to a large nonlinear phase shift and, thus, an effective electro-optic nonlinear refractive index. The effective nonlinearity can be either positive or negative, causing the second-harmonic spectra to move toward the coupling center, which, in turn, offered us a way to measure the effective electro-optic nonlinear refractive index. The corresponding enhanced Kerr electro-optic nonlinearity is more than three orders of magnitude higher than the intrinsic value. These results open a door to manipulate the nonlinear phase by applying an external electric field instead of light intensity in noncentrosymmetric crystals.
Photonics Research
- Publication Date: Jun. 18, 2015
- Vol. 3, Issue 4, 04000168 (2015)
Enhanced optical Kerr nonlinearity of MoS2 on silicon waveguides
Linghai Liu, Ke Xu, Xi Wan, Jianbin Xu, Chi Yan Wong, and Hon Ki Tsang
A quasi-two-dimensional layer of MoS2 was placed on top of a silicon optical waveguide to form a MoS2–silicon hybrid structure. Chirped pulse self-phase modulation measurements were carried out to determine the optical Kerr nonlinearity of the structure. The observed increase in the spectral broadening of the optical pulses in the MoS2–silicon waveguide compared with the silicon waveguides indicated that the third-order nonlinear effect in MoS2 is about 2 orders of magnitude larger than that in silicon. The measurements show that MoS2 has an effective optical Kerr coefficient of about 1.1 × 10?16 m2∕W. This work reveals the potential application of MoS2 to enhance the nonlinearity of hybrid silicon optical devices. A quasi-two-dimensional layer of MoS2 was placed on top of a silicon optical waveguide to form a MoS2–silicon hybrid structure. Chirped pulse self-phase modulation measurements were carried out to determine the optical Kerr nonlinearity of the structure. The observed increase in the spectral broadening of the optical pulses in the MoS2–silicon waveguide compared with the silicon waveguides indicated that the third-order nonlinear effect in MoS2 is about 2 orders of magnitude larger than that in silicon. The measurements show that MoS2 has an effective optical Kerr coefficient of about 1.1 × 10?16 m2∕W. This work reveals the potential application of MoS2 to enhance the nonlinearity of hybrid silicon optical devices.
Photonics Research
- Publication Date: Aug. 07, 2015
- Vol. 3, Issue 5, 05000206 (2015)
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