Showing papers by "Luis Pesquera published in 2019"

Numerical and experimental analysis of optical frequency comb generation in gain-switched semiconductor lasers

Abstract: This work was funded by the Ministerio de Economia y Competitividad of Spain (COMBINA, TEC201565212-C3-1-P and TEC201565212-C3-2-P). A. Rosado, A. Perez-Serrano, J. M. G. Tijero and I. Esquivias also acknowledge support from Comunidad de Madrid and European Structural Funds under program SINFOTON2-CM (P2018/NMT-4326). A. Perez-Serrano acknowledges support from the Programa Propio of the Universidad Politecnica de Madrid.

Enhanced optical frequency comb generation by pulsed gain-switching of optically injected semiconductor lasers.

Abstract: We report on the experimental generation of broad and flat optical frequency combs (OFC) in a 1550 nm laser diode using gain switching with pulsed electrical excitation together with optical injection. The combination of both techniques allows the generation of high-quality OFCs at a repetition frequency of 500 MHz, showing a low-noise optical spectrum with unprecedent features in terms of width (108 tones within 10 dB) and flatness (56 tones within 3 dB) in comparison with those previously reported for this modulation frequency. The influence of the injection conditions on the OFC quality is studied. Using these two techniques, it has been possible to reduce the separation between tones, generating high spectral performance OFCs with a repetition rateof 100 MHz.

Tackling the Trade-Off Between Information Processing Capacity and Rate in Delay-Based Reservoir Computers

Abstract: We study the role of the system response time in the computational capacity of delay-based reservoir computers. Photonic hardware implementation of these systems offers high processing speed. However, delay-based reservoir computers have a trade-off between computational capacity and processing speed %an intrinsic speed limitation due to the non-zero response time of the nonlinear node. The reservoir state is obtained from the sampled output of the nonlinear node. We show that the computational capacity is degraded when the sampling output rate is higher than the inverse of the system response time. We find that the computational capacity depends not only on the sampling output rate but also on the misalignment between the delay time of the nonlinear node and the data injection time. We show that the capacity degradation due to the high sampling output rate can be reduced when the delay time is greater than the data injection time. We find that this mismatch gives an improvement of the performance of delay-based reservoir computers for several benchmarking tasks. Our results show that the processing speed of delay-based reservoir computers can be increased while keeping a good computational capacity by using a mismatch between delay and data injection times. It is also shown that computational capacity for high sampling output rates can be further increased by using an extra feedback line and delay times greater than the data injection time.

Analysis of Optical Frequency Comb Generation in Gain-Switched Semiconductor Lasers

Abstract: An Optical Frequency Comb (OFC) Generator is a laser source emitting an equally spaced group of optical tones. These types of optical sources have found application in different fields, such as spectroscopy [1] and optical communications [2]. Among the three main techniques for generating OFCs from semiconductor lasers, namely gain switching, electro-optic modulation and mode-locking, gain switching (GS) has attracted attention due to the simple selection of the repetition frequency and its easy implementation and low cost.

Optical Frequency Comb Generation from Semiconductor Lasers using Optical Injection and Pulsed Gain Switching

Abstract: An Optical Frequency Comb (OFC) Generator is a laser source emitting a coherent radiation with an equally spaced group of optical frequencies. OFCs have been used in numerous fields, such as optical communications [1], RF photonics [2] and infrared spectroscopy [3]. Relatively low repetition rate OFCs (100–1000 MHz) are especially suited for dual comb spectroscopic applications. Low repetition rate OFCs from Gain-Switched (GS) semiconductor lasers using sinusoidal excitation have been reported for spectroscopic applications [4]. On the other hand, the generation of ultra-short optical pulses by pulsed excitation GS has been demonstrated [5], but as far as we know, it has not been used for OFC generation.