Au-Mg improved ohmic contacts to p-GaAs

Optics Express, 2012

We investigate the effects of different phase noise processes of SGDBR laser on coherent systems. The SGDBR device operated well with QPSK modulation at 5 Gbaud, while the performance of 16-QAM was significantly degraded due to excess noise. The white FM noise mainly defines the ultimate performance of coherent reception, but the low frequency excess noise can potentially degrade the performance of systems that employ 16-QAM format at 5 Gbaud.

IEEE Journal of Quantum Electronics, 2000

Quantum-dot (QD) lasers exhibit many useful properties such as low threshold current, temperature and feedback insensitivity, chirpless behavior, and low linewidth enhancement factor ( H -factor). Although many breakthroughs have been demonstrated, the maximum modulation bandwidth remains limited in QD devices, and a strong damping of the modulation response is usually observed pointing out the role of gain compression. This paper investigates the influence of the gain compression in a 1.3-m InAs-GaAs QD laser and its consequences on the

Applied Optics, 1989

If authors will state in their covering communications whether they expect their institutions to pay the publication charge, publication time should be shortened {for those who do).

2013

The objectives of this thesis are to measure the frequency noise of a widely tunable semiconductor laser, determine the main causes for the frequency uctuations and investigate the requirements for laser frequency noise for mQAM modulation formats by means of simulations. The following theoretical aspects are covered: the derivation of the frequency noise spectrum and the detuned loading effect from the rate equations; the shape and the causes of the frequency noise power spectral density; the derivation of the linewidth spectrum from white and 1/f frequency noise; the functionality of the laser and feedback loop used for the measurements. Measurements using the feedback loop showed substantial improvements in the -3 dB laser line width, but further investigation is needed in order to obtain a laser that is suitable both as a transmitter and as a local oscillator in coherent communication. Simulations outlined the dependence of linewidth, constellation diagrams and symbol error rate...

Optics express, 2010

By using a 200GHz AWG channelized ASE source in connection with a saturable semiconductor optical amplifier (SOA) based noise blocker as the injecting source at the remote node in front of the local optical network units (ONUs), we demonstrate the spectrum-sliced ASE transmitter with greatly suppressed intensity noise performance in WDM-PON network. Such channelized SOA filtering technique effectively reduces the relative intensity noise of the ASE source by at least 4.5 dB. The low-noise WRC-FPLD transmitter improves its extinction-ratio (ER) from 8.9 to 9.6 dB and signal-to-noise ratio (SNR) from 5.9 to 6.3 dB. In comparison with broad-band ASE injection-locked WRC-FPLD transmitter at same power, there is an improvement on receiving power penalty (∆P Receiver ) by 2 dB at BER 10 −9 in back-to-back case, and the receiving power of BER 10 −9 can achieve −24 dBm even after 25km fiber transmission. With additional AWG filtering, the intraband crosstalk effect between the upstream transmitted data and the reflected ASE signal is significantly reduced by 6.3dB. The compromised effects of ER and SNR on BER performance are also elucidated via the modified SNR model for the WRC-FPLD under ASE injection induced gain-saturation condition. The ∆P Receiver /∆SNR of 8.89 at same ER condition is more pronounced than the ∆P Receiver /∆ER of 3.17 obtained under same SNR condition, indicating that the SNR plays a more important role than the ER on enhancing the BER performance.

IEEE Journal of Quantum Electronics, 1991

IEEE Journal of Quantum Electronics, 2000

Four different theoretical formulations for AM and FM quantum noise properties in semiconductor lasers are compared with each other for AlGaAs lasers. These formulations are based on van der Pol, Fokker-Planck, rate, and photon density matrix equations. Experimental results with AM noise spectra, FM noise spectra, and spectral linewidths for four different types of AlGaAs lasers are also delineated and compared with the theoretical predictions. The spontaneous emission coefficient p and population inversion parameter nsp, which are basic parameters for determining the quantum noise properties of semiconductor lasers, were calculated by the density of states with Kane function interpolated to Halperin-Lax bandtail and the Stern's improved matrix element. Experimental AM and FM quantum noise properties show good agreement with the theoretical predictions derived through use of estimated p and nsp values.

IEEE Photonics Technology Letters, 2000

Abstruct-We present experimental results on the highfrequency electrical impedance of In0 35 Gao 6 5 As-GaAs multiquantum-well lasers with varied p-doping levels in the active region. The analysis of the data, using a simple three rate equation model, provides information about the dynamical time constants (the carrier lifetime, the effective carrier capture and escape times) under the laser operation conditions. The addition of p-doping increases the carrier escape time at threshold from 0.7 ns, extracted for the undoped devices, up to a value higher than 2 ns for the p-doped lasers. The effective capture time is estimated to be between 2 and 5 ps.