Theory of noise in a kilo-Hz cascaded high-energy Yb-doped nanosecond pulsed fiber amplifier

A theoretical analysis of noise in a high-power cascaded fiber amplifier is presented. Unlike the noise theory in low power communication, the noise of a high power system is redefined as the leaked output energy between pulses with coherent beat noise uncounted. This definition is more appropriate for high power usage in which the pulse energy receives more attention than the pulse shape integrity. Then the low power pre-amplifying stages are considered as linear amplification and analyzed by linear theory. In the high-power amplification stages, the inversion is assumed to recover linearly in the time interval between pulses. The time shape of the output pulse is different from that of the input signal because of different gains at the front and back ends of the pulse. Then, a criterion is provided to distinguish the nonlinear and linear amplifications based on the signal-to-noise ratio （SNR） analysis. Then, an experiment that shows that the output SNR actually drops off in nonlinear amplification is performed. The change in the noise factor can be well evaluated by pulse shape distortion.

Low-Threshold Broadband Spectrum Generation by Amplification of Cascaded Stimulated Raman Scattering in an Ytterbium-Doped Fiber Amplifier

We present an experimental study on low-threshold broadband spectrum generation mainly due to the amplirfication of the cascaded stimulated Raman scattering （SRS） effect in a four-stage fiber master oscillator power amplifier system. The cascaded SRS is achieved by using a long passive fiber pumped by a pulsed fiber laser cen： tered at wavelength 1064 nm. The amplified spontaneous emission during the amplification process is efficiently suppressed by cutting the length of the passive fiber and by using a double-clad ytterbium-doped fiber amplifier. The generated broadband spectrum spans from 960nm to 1700nm with maximum average output 13.6 W and average spectral power density approximately 17. 7 mW/nm.

Bimetallic nanoparticles as cascade sensitizing amplifiers for low-dose and robust cancer radio-immunotherapy

Radiotherapy(RT)is one of the most feasible and routinely used therapeutic modalities for treating malignant tumors.In particular,immune responses triggered by RT,known as radio-immunotherapy,can partially inhibit the growth of distantly spreading tumors and recurrent tumors.How-ever,the safety and efficacy of radio-immunotherapy is impeded by the radio-resistance and poor immu-nogenicity of tumor.Herein,we report oxaliplatin(IV)-iron bimetallic nanoparticles(OXA/Fe NPs)as cascade sensitizing amplifiers for low-dose and robust radio-immunotherapy.The OXA/Fe NPs exhibit tumor-specific accumulation and activation of OXA(I)and Fe^(2+)in response to the reductive and acidic microenvironment within tumor cells.The cascade reactions of the released metallic drugs can sensitize RT by inducing DNA damage,increasing ROS and O_(2) levels,and amplifying the immunogenic cell death(ICD)effect after RT to facilitate potent immune activation.As a result,OXA/Fe NPs-based low-dose RT triggered a robust immune response and inhibited the distant and metastatic tumors effectively by a strong abscopal effect.Moreover,a long-term immunological memory effect to protect mice from tumor rechal-lenging is observed.Overall,the bimetallic NPs-based cascade sensitizing amplifier system offers an effi-cient radio-immunotherapy regimen that addresses the key challenges.

Optical Nonlinearity in a Novel Optical Signal Regeneration System Based on Cross-Gain Modulation Using Cascaded Semiconductor Optical Amplifiers

We propose a novel optical signal regeneration system based on wavelength converters by use of cross gain modulation in cascaded semiconductor optical amplifiers. The nonlinearity in optical input/output characteristics and eye opening using NRZ signal were archived.

750Mb/s monochromatic LED-based real-time visible light communication system employing a low-complexity cascaded post-equalizer

We experimentally demonstrate a 750 Mb/s real-time visible light communication（VLC） system based on non-return-to-zero on–off keying modulation by employing single commercially available monochromatic lightemitting diodes. To enhance the 3-d B bandwidth of the VLC link, we propose a low-complexity cascaded post-equalizer based on NPN transistors. With two different frequency-selecting networks in our post-equalizer,the highest achieved 3-d B bandwidth of the VLC link is 370 MHz. The highest achieved data rate is 750 Mb/s at a communication distance of 170 cm with a bit error rate below 1 × 10^（-6）, which is far below the forward error correction limit（3.8 × 10^（-3））. Based on our monochromatic VLC system, a wavelength-division multiplexing VLC system could be designed with a higher data rate.

A 30-dB 1-16-GHz low noise IF amplifier in 90-nm CMOS

This paper presents a high-gain wideband low-noise IF amplifier aimed for the ALMA front end system using 90-nm LP CMOS technology.A topology of three optimized cascading stages is proposed to achieve a flat and wideband gain.Incorporating an input inductor and a gate-inductive gain-peaking inductor,the active shunt feedback technique is employed to extend the matching bandwidth and optimize the noise figure.The circuit achieves a flat gain of 30.5 dB with 3 dB bandwidth of 1-16 GHz and a minimum noise figure of 3.76 dB.Under 1.2 V supply voltage,the proposed IF amplifier consumes 42 mW DC power.The chip die including pads takes up 0.53 mm~2,while the active area is only 0.022 mm~2.