A. Sapia

Polarization switching in semiconductor lasers driven via injection from an external radiation

Switching between transverse electric (TE) and transverse magnetic (TM) polarization states in the output from a semiconductor laser is experimentally obtained through injection locking from an external TM polarized radiation. Switching, which is connected to the loss reduction of the TM modes caused by the injection‐locking mechanism, is faster than a few nanoseconds, the resolution limit of our apparatus.

Transient multimode dynamics in nearly single-mode lasers

The transient dynamics of nearly single-mode semiconductor lasers is studied analytically and numerically for lasers biased below threshold. The side-mode excitation probability is evaluated by solving a Fokker-Planck equation approximately. The validity of the approximate solution is verified through Monte Carlo simulations of the corresponding Langevin equations. The results show the relevance of the carrier-density overshoot during laser turn-on in determining the side-mode excitation probability. They also indicate the dependence of this probability on various device parameters such as the gain margin between the main and side modes. The experiments performed by using distributed feedback (DFB) semiconductor lasers show qualitative agreement with theory. >

Pattern effects in time jitter of semiconductor lasers

The effect of fast repetitive pulse modulation on the value of time jitter affecting the optical pulses emitted by semiconductor lasers is studied both experimentally and by numerical simulations. The results show that the modulation also induces pattern effects that increase the value of time jitter to non‐negligible values for bias above threshold.

Quasi-deterministic theory of semiconductor-laser gain switching

The anomalous enhancement of fluctuations during gain switching of semiconductor lasers is considered. An extension of the quasi-deterministic theory is performed to account for the nonlinear dynamics of the process. The results are in quantitative agreement with those of a computer simulation of the Langevin rate equations describing the process.

Absolute Frequency Stabilization of a Tunable Tm:Ho:YAG Laser to the HBr P(12) Line at 2097 nm

We demonstrate absolute frequency stabilization of a widely tunable Tm:Ho:YAG laser by locking the oscillator to the P(12) absorption line of the H(79)Br molecule at 2097.222 nm, using the fringe side-locking technique. We perform time and spectral analysis of open- and closed-loop error signals to evaluate the frequency noise. In closed-loop operation a long-term frequency stability of better than 2 MHz with rms frequency fluctuations of approximately 112 kHz is obtained over an observation time of 10(3) s.

Nonlinearity difference in the two passbands of a distributed-feedback semiconductor laser amplifier.

The nonlinearity difference in the two passbands of a distributed-feedback semiconductor laser amplifier was studied experimentally. A theoretical explanation was given by using the transmission matrix approach. The difference of nonlinearity in the two passbands was found to be enhanced greatly by the mechanism of asymmetric facet reflection.

Statistical distribution of frequency fluctuations in semiconductor lasers

We present experimental results showing a departure from the usually assumed Gaussian statistics of the fluctuations of the instantaneous emission frequency in single-mode semiconductor lasers operating under the influence of an external optical feedback. The amount of this departure is studied and analyzed under various operating conditions.

Non-Gaussian statistics of frequency fluctuations in line-narrowed semiconductor lasers

The statistics of the instantaneous frequency fluctuations of CW narrowed-linewidth single-mode semiconductor lasers are studied under the most general conditions. In the case in which the rate equations describing the evolution of the system cannot be linearized the statistics are found to deviate appreciably from a Gaussian distribution. A Monte Carlo simulation is shown to give results in good agreement with previous experimental measurements. >

Analytical results of the switch on statistics in distributed feedback laser diodes by short triangular pulses

The results of a theoretical analysis of the first passage time statistics in single mode diode lasers are reported. A fast triangular current pulse is used to drive a semiconductor laser in order to approximate working conditions close to those obtained when the transmission rate is limited by the parasitics of the driving circuit. The results show a very good agreement with numerical simulations of the nonlinear evolution of the dynamical system demonstrating the accuracy of the approximations involved in our theory.

Connection between linewidth saturation and power increase of transverse magnetic mode in ridge distributed feedback lasers

We present some experimental results of ridge distributed feedback semiconductor lasers showing a linewidth broadening at high emission power which is due to the growth of transverse magnetic polarized radiation. We also show how the linewidth saturation can be ascribed to an increase in the low‐frequency content of the phase noise spectrum. This increase at low frequency is also linked to a deformation in the probability distribution of the instantaneous optical emission frequency.