Influence of Size of ZnO Nanorods on Light Extraction Enhancement of GaN-Based Light-Emitting Diodes

We investigate the influence of size of ZnO nanorods on the light extraction efficiency(LEE)enhancement of GaN-based light-emitting diodes(GaN-LEDs).ZnO nanorods with different sizes are hydrothermally grown on patterned indium-doped tin oxide(ITO)electrodes of the GaN-LEDs in zinc acetate aqueous solutions of different concentrations.Measurements are conducted for the LEE enhancement of the LEDs with ZnO nanorods,compared to these without ZnO nanorods.The results suggest that the LEE of the LEDs with ZnO nanorods increases with the increasing size of ZnO nanorods.However,a saturation trend for the LEE improvement is also observed,which is attributed to the maximum limitation of light coupled into ZnO nanorods from GaN-based LEDs,and the reflection is increased by the increasing top surface of the ZnO nanorods.

Characteristics measurement of gain and refractive index of traveling-wave semiconductor optical amplifier

A novel method to measure the gain and refractive index characteristics of traveling-wave semiconductor optical amplifier（TMA） is presented. In-out fiber ends of TWA are used to construct an external cavity resonator to produce big ripple on amplified spontaneous emission（ASE） spectrum. By this means,Hakki-Paoli method is adepted to obtain the gain spectra of TWA over a wide spectral range. From measured longitudinal mode spacing and peak wavelength shift due to increased bias current, we further calculate the effective refractive index and the refractive index change. Special feature of refractive index change above lasing threshold is revealed and explained.

Design and experimental study of compensation fitting on the angle-tuned filters

For a 100 GHz DWDM angle-tuned filter with low polarization dependent loss,the insertion loss and the Gaussian-transformation tendency of the transmission spectrum will become more serious as the incident angle is increased. It is because of that the optical path and the transmission modes of the thin film filter will change when the incident angle is varied. According to the thin film matrix theory,the analysis model is established,the displacement change of the transmission field is simulated,and a dynamic compensation fitting is also designed and fabricated in the paper. The experimental results show that it can effectively reduce the insertion loss and the phenomenon of Gaussian process. Using the compensation fitting,the tunable range of the filter is at about 20 nm which coincides with the theoretical design.

A 40-Gbit/s 1-to-2 Photonic Data Distributor Employing a Single Semiconductor Optical Amplifier

A simple design of 1-to-2 photonic data distributor is proposed.A proof-of-concept experiment is performed at 40 Gbit/s employing four-wave mixing and cross gain modulation in a single semiconductor optical amplifier.Correct output logic signals with high extinction ratios(over 11 dB)and clear open eyes are obtained,without using any additional input light beam.The scheme would be a promising candidate for future ultrafast all-optical signal processing applications.

All-Optical Temporal Differentiator Using a High Resolution Optical Arbitrary Waveform Shaper

We experimentally demonstrate an all-optical temporal differentiator using a high resolution optical arbitrary waveform shaper,which is based on liquid crystal on silicon switching elements,and both amplitude and phase of the spectrum are programmable.By designing specific transfer functions with the optical waveform shaper,we obtain first-,second-,and third-order differentiators for periodic pulses with small average errors.We also theoretically analyze the bandwidth limitation of optical waveform shaper on the differentiator.

Effects of an InGaAs Cap Layer on the Optical Properties of InAs Quantum Dot Molecules

Self-assembled InAs quantum dot molecules are grown on GaAs substrates without following any special protocols by using metal-organic chemical vapor deposition.The effects of indium composition and the thickness of the InGaAs cap layer on the optical properties of InAs quantum dot molecules are investigated by photoluminescence.With increasing indium composition and thickness of the InGaAs cap layer,the ground-state wavelength of the emission spectrum redshifts and the peak intensity decreases.In addition,the structural and optical properties of quantum dots and quantum dot molecules are comparatively studied,and the results show that when quantum dots turn into quantum dot molecules,the emission wavelength red shifts.