Automatic classification of the frequency chirp in directly modulated lasers using cross-correlation

Abstract

An automatic method to discriminate between adiabatic and transient-chirp dominated directly modulated semiconductor lasers (DML), useful to classify telecommunications transmitters, is presented. It is based on calculating the crosscorrelation between the optical power and chirp waveforms of the device under test and the use of a decision threshold. The accuracy of the algorithm is demonstrated using simulated signals obtained from a well-tested laser model complemented with experimentally-derived parameters for several real lasers. By modifying the confinement factor, the laser chirp behavior can gradually be transformed from transient to adiabatic, thus enabling the validation of the proposed algorithm. Correct classification results are reported. Due to its flexibility, ease of implementation, simplicity and accuracy, the classification algorithm here put forward, represents a practical tool for testing and fabrication of DMLs.

Review on the Millimeter-Wave Generation Techniques Based on Photon Assisted for the RoF Network System

“…Leading to the broadening of the optical pulse, the pulse will overlap with the next pulse which is called intersymbol interference (ISI) [20]. In addition, as the current change would affect the active region refractive index of the semiguided laser and lead to the change of resonant wavelength, additional phase modulation and frequency chirp will be introduced which will affect the modulation performance [21,22]. Generally, direct modulation is not suitable for high-frequency RoF network systems.…”

Photonic generation of frequency 12‐tupling millimeter‐wave based on three cascaded‐MZMs and polarization multiplexing

“…The mm-wave signal generation integrated with radio-over-fiber (RoF) technology has been considered as a predominant candidate to provide unrestricted access and remote signal delivery in next-generation broadband wireless transmission. The generation of mm-wave carriers in optical domain can be achieved using several approaches like a dual-mode laser, 6 optical injection locking, 7 direct modulation, 8,9 external modulation, [10][11][12][13] and optical heterodyning. 14 In comparison with other methodologies, mm-wave generation employing external modulation has attracted considerable attention due to better stability, high spectral purity, and large tunability range.…”