Static and dynamic characteristics of an InAs/InP quantum-dot optical amplifier operating at high temperatures

We report on high quality InAs/InP quantum dot optical amplifiers for the 1550 nm wavelength range operating over a wide temperature range of 25 to 100 °C. A temperature dependent shift of the peak gain wavelength at a rate of 0.78 nm/K is observed. Consequently, two possible modes of operation are performed for a systematic device characterization over the entire temperature range. In the first mode, the signal wavelength is tuned to always match the peak gain wavelength while in the second mode, the signal wavelength is kept constant as the gain spectrum shifts with the temperature. Static characteristics, such as gain spectra and saturation levels, as well as dynamical properties, are presented. Distortion-less amplification of a single 28 Gbit/s signal and cross-talk free amplification of two channels, detuned by 2 nm, were demonstrated over the entire temperature range.

Optical control of capacitance in a metal-insulator-semiconductor diode with embedded metal nanoparticles

This paper describes a metal-insulator-semiconductor (MIS) capacitor with flat capacitance voltage characteristics and a small quadratic voltage capacitance coefficient. The device characteristics resemble a metal-insulator-metal diode except that here the capacitance depends on illumination and exhibits a strong frequency dispersion. The device incorporates Fe nanoparticles (NPs), mixed with SrF₂, which are embedded in an insulator stack of SiO₂ and HfO₂. Positively charged Fe ions induce dipole type traps with an electronic polarization that is enhanced by photogenerated carriers injected from the substrate and/or by inter nanoparticle exchange of carriers. The obtained characteristics are compared with those of five other MIS structures: two based on Fe NPs, one with and the other without SrF₂ sublayers. Additionally, devices contain Co NPs embedded in SrF₂ sublayers, and finally, two structures have no NPs, with one based on a stack of SiO₂ and HfO₂ and the other which also includes SrF₂. Only structures containing Fe NPs, which are incorporated into SrF₂, yield a voltage independent capacitance, the level of which can be changed by illumination. These properties are essential in radio frequency/analog mixed signal applications.

Cross talk free multi channel processing of 10 Gbit/s data via four wave mixing in a 1550 nm InAs/InP quantum dash amplifier

We demonstrate multi wavelength processing in a broad band 1550 nm quantum dash optical amplifier. Two 10 Gbit/s signals, spectrally separated by 30 nm are individually wavelength converted via four wave mixing (FWM) with no cross talk. High power signal levels cause depletion of high energy and wetting layer states resulting in some homogenizing of the gain medium and generation of cross FWM components near each channel due to FWM in the other channel. These do not affect the cross-talkless multichannel processing except when the two channels use equal detuning between signal and pump.

Direct observation of the coherent spectral hole in the noise spectrum of a saturated InAs/InP quantum dash amplifier operating near 1550 nm

We demonstrate a direct observation of the coherent noise spectral hole in a saturated quantum dash amplifier. Its width 500-600 GHz is determined by the response time and is responsible for high speed regeneration properties.

Direct correlation between a highly damped modulation response and ultra low relative intensity noise in an InAs/GaAs quantum dot laser

We describe modulation responses and relative intensity noise (RIN) spectra of an InAs/GaAs quantum dot laser operating near 1300 nm. A very large nonlinear gain compression coefficient yields a highly damped modulation response with a maximum 3 dB bandwidth of ~6.5 GHz and flat RIN spectra which reach as low a level as -158/-160 dB/Hz at frequencies up to 10 GHz.