Editorial

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4 pages, 188 KiB

Open AccessEditorial

Special Issue “Semiconductor Laser Dynamics: Fundamentals and Applications”

by

Daan Lenstra

Photonics 2020, 7(2), 40; https://doi.org/10.3390/photonics7020040 - 11 Jun 2020

Cited by 1 | Viewed by 2650

Abstract

With the advent of integrated photonics, a crucial role is played by semiconductor diode lasers (SDLs) as coherent light sources. Old paradigms of semiconductor laser dynamics, like optical injection, external feedback and the coupling of lasers, regained relevance when SDLs were integrated on [...] Read more.

With the advent of integrated photonics, a crucial role is played by semiconductor diode lasers (SDLs) as coherent light sources. Old paradigms of semiconductor laser dynamics, like optical injection, external feedback and the coupling of lasers, regained relevance when SDLs were integrated on photonic chips. This Special Issue presents a collection of seven invited feature papers and 11 contributed papers reporting on recent advances in semiconductor laser dynamics. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

Research

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15 pages, 2049 KiB

Open AccessArticle

Orbital Instability of Chaotic Laser Diode with Optical Injection and Electronically Applied Chaotic Signal

by

Satoshi Ebisawa

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Shinichi Komatsu

Photonics 2020, 7(2), 25; https://doi.org/10.3390/photonics7020025 - 30 Mar 2020

Cited by 4 | Viewed by 2420

Abstract

We numerically studied the chaotic dynamics of a laser diode (LD) system with optical injection, where a chaotic signal, which is generated by an LD with optical feedback, is applied to the drive current of the master LD. To quantify the orbital instability [...] Read more.

We numerically studied the chaotic dynamics of a laser diode (LD) system with optical injection, where a chaotic signal, which is generated by an LD with optical feedback, is applied to the drive current of the master LD. To quantify the orbital instability of the slave LD, the Lyapunov exponent was calculated as a function of the optical injection ratio between the master and slave LDs and the optical feedback ratio of the applied signal. We found that the Lyapunov exponent was increased and the orbital instability was enhanced by applying a chaotic signal when the inherent system without the applied signal was in a “window”. Next, we investigated the orbital instability of the slave LD in terms of statistical and dynamical quantities of the applied chaotic signal. The maximal value of the Lyapunov exponent for a certain range of the injection ratio was calculated and we showed that a chaotic pulsation is suitable for enhancing the orbital instability of the LD system. We then investigated chaos synchronization between the LDs. It is concluded that the orbital instability of an LD with optical injection can be enhanced by applying chaotic pulsation without chaos synchronization. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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10 pages, 1373 KiB

Open AccessEditor’s ChoiceArticle

Equivalent Circuit Model of High-Performance VCSELs

by

Marwan Bou Sanayeh

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Wissam Hamad

and

Werner Hofmann

Photonics 2020, 7(1), 13; https://doi.org/10.3390/photonics7010013 - 18 Jan 2020

Cited by 4 | Viewed by 5118

Abstract

In this work, a general equivalent circuit model based on the carrier reservoir splitting approach in high-performance multi-mode vertical-cavity surface-emitting lasers (VCSELs) is presented. This model accurately describes the intrinsic dynamic behavior of these VCSELs for the case where the lasing modes do [...] Read more.

In this work, a general equivalent circuit model based on the carrier reservoir splitting approach in high-performance multi-mode vertical-cavity surface-emitting lasers (VCSELs) is presented. This model accurately describes the intrinsic dynamic behavior of these VCSELs for the case where the lasing modes do not share a common carrier reservoir. Moreover, this circuit model is derived from advanced multi-mode rate equations that take into account the effect of spatial hole-burning, gain compression, and inhomogeneity in the carrier distribution between the lasing mode ensembles. The validity of the model is confirmed through simulation of the intrinsic modulation response of these lasers. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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12 pages, 3199 KiB

Open AccessArticle

Development of an Interference Filter-Stabilized External-Cavity Diode Laser for Space Applications

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Photonics 2020, 7(1), 12; https://doi.org/10.3390/photonics7010012 - 18 Jan 2020

Cited by 17 | Viewed by 5646

Abstract

The National Time Service Center of China is developing a compact, highly stable, 698 nm external-cavity diode laser (ECDL) for dedicated use in a space strontium optical clock. This article presents the optical design, structural design, and preliminary performance of this ECDL. The [...] Read more.

The National Time Service Center of China is developing a compact, highly stable, 698 nm external-cavity diode laser (ECDL) for dedicated use in a space strontium optical clock. This article presents the optical design, structural design, and preliminary performance of this ECDL. The ECDL uses a narrow-bandwidth interference filter for spectral selection and a cat’s-eye reflector for light feedback. To ensure long-term stable laser operation suitable for space applications, the connections among all the components are rigid and the design avoids any spring-loaded adjustment. The frequency of the first lateral rocking eigenmode is 2316 Hz. The ECDL operates near 698.45 nm, and it has a current-controlled tuning range over 40 GHz and a PZT-controlled tuning range of 3 GHz. The linewidth measured by the heterodyne beating between the ECDL and an ultra-stable laser with 1 Hz linewidth is about 180 kHz. At present, the ECDL has been applied to the principle prototype of the space ultra-stable laser system. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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14 pages, 791 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Synchronization of Mutually Delay-Coupled Quantum Cascade Lasers with Distinct Pump Strengths

by

Thomas Erneux

and

Daan Lenstra

Photonics 2019, 6(4), 125; https://doi.org/10.3390/photonics6040125 - 10 Dec 2019

Cited by 14 | Viewed by 2499

Abstract

The rate equations for two delay-coupled quantum cascade lasers are investigated analytically in the limit of weak coupling and small frequency detuning. We mathematically derive two coupled Adler delay differential equations for the phases of the two electrical fields and show that these [...] Read more.

The rate equations for two delay-coupled quantum cascade lasers are investigated analytically in the limit of weak coupling and small frequency detuning. We mathematically derive two coupled Adler delay differential equations for the phases of the two electrical fields and show that these equations are no longer valid if the ratio of the two pump parameters is below a critical power of the coupling constant. We analyze this particular case and derive new equations for a single optically injected laser where the delay is no longer present in the arguments of the dependent variables. Our analysis is motivated by the observations of Bogris et al. (IEEE J. Sel. Top. Quant. El. 23, 1500107 (2017)), who found better sensing performance using two coupled quantum cascade lasers when one laser was operating close to the threshold. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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11 pages, 943 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Task-Independent Computational Abilities of Semiconductor Lasers with Delayed Optical Feedback for Reservoir Computing

by

Krishan Harkhoe

and

Guy Van der Sande

Photonics 2019, 6(4), 124; https://doi.org/10.3390/photonics6040124 - 02 Dec 2019

Cited by 20 | Viewed by 3274

Abstract

Reservoir computing has rekindled neuromorphic computing in photonics. One of the simplest technological implementations of reservoir computing consists of a semiconductor laser with delayed optical feedback. In this delay-based scheme, virtual nodes are distributed in time with a certain node distance and form [...] Read more.

Reservoir computing has rekindled neuromorphic computing in photonics. One of the simplest technological implementations of reservoir computing consists of a semiconductor laser with delayed optical feedback. In this delay-based scheme, virtual nodes are distributed in time with a certain node distance and form a time-multiplexed network. The information processing performance of a semiconductor laser-based reservoir computing (RC) system is usually analysed by way of testing the laser-based reservoir computer on specific benchmark tasks. In this work, we will illustrate the optimal performance of the system on a chaotic time-series prediction benchmark. However, the goal is to analyse the reservoir’s performance in a task-independent way. This is done by calculating the computational capacity, a measure for the total number of independent calculations that the system can handle. We focus on the dependence of the computational capacity on the specifics of the masking procedure. We find that the computational capacity depends strongly on the virtual node distance with an optimal node spacing of 30 ps. In addition, we show that the computational capacity can be further increased by allowing for a well chosen mismatch between delay and input data sample time. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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9 pages, 1965 KiB

Open AccessArticle

Parity–Time Symmetry in Bidirectionally Coupled Semiconductor Lasers

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Photonics 2019, 6(4), 122; https://doi.org/10.3390/photonics6040122 - 27 Nov 2019

Cited by 7 | Viewed by 2746

Abstract

We report on the numerical analysis of intensity dynamics of a pair of mutually coupled, single-mode semiconductor lasers that are operated in a configuration that leads to features reminiscent of parity–time symmetry. Starting from the rate equations for the intracavity electric fields of [...] Read more.

We report on the numerical analysis of intensity dynamics of a pair of mutually coupled, single-mode semiconductor lasers that are operated in a configuration that leads to features reminiscent of parity–time symmetry. Starting from the rate equations for the intracavity electric fields of the two lasers and the rate equations for carrier inversions, we show how these equations reduce to a simple 2 × 2 effective Hamiltonian that is identical to that of a typical parity–time (PT)-symmetric dimer. After establishing that a pair of coupled semiconductor lasers could be PT-symmetric, we solve the full set of rate equations and show that despite complicating factors like gain saturation and nonlinearities, the rate equation model predicts intensity dynamics that are akin to those in a PT-symmetric system. The article describes some of the advantages of using semiconductor lasers to realize a PT-symmetric system and concludes with some possible directions for future work on this system. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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11 pages, 4447 KiB

Open AccessArticle

Optical Feedback Sensitivity of a Semiconductor Ring Laser with Tunable Directionality

by

Guy Verschaffelt

,

Mulham Khoder

and

Guy Van der Sande

Photonics 2019, 6(4), 112; https://doi.org/10.3390/photonics6040112 - 28 Oct 2019

Cited by 6 | Viewed by 2741

Abstract

We discuss the sensitivity to optical feedback of a semiconductor ring laser that is made to emit in a single-longitudinal mode by applying on-chip filtered optical feedback in one of the directional modes. The device is fabricated on a generic photonics integration platform [...] Read more.

We discuss the sensitivity to optical feedback of a semiconductor ring laser that is made to emit in a single-longitudinal mode by applying on-chip filtered optical feedback in one of the directional modes. The device is fabricated on a generic photonics integration platform using standard components. By varying the filtered feedback strength, we can tune the wavelength and directionality of the laser. Beside this, filtered optical feedback results in a limited reduction of the sensitivity for optical feedback from an off-chip optical reflection when the laser is operating in the unidirectional regime. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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14 pages, 5918 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

A Comparison between off and On-Chip Injection Locking in a Photonic Integrated Circuit

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Photonics 2019, 6(4), 103; https://doi.org/10.3390/photonics6040103 - 01 Oct 2019

Cited by 7 | Viewed by 3030

Abstract

The mutual and injection locking characteristics of two integrated lasers are compared, both on and off-chip. In this study, two integrated single facet slotted Fabry–Pérot lasers are utilised to develop the measurement technique used to examine the different operational regimes arising from optically [...] Read more.

The mutual and injection locking characteristics of two integrated lasers are compared, both on and off-chip. In this study, two integrated single facet slotted Fabry–Pérot lasers are utilised to develop the measurement technique used to examine the different operational regimes arising from optically locking a semiconductor diode laser. The technique employed used an optical spectrum analyser (OSA), an electrical spectrum analyser (ESA) and a high speed oscilloscope (HSO). The wavelengths of the lasers are measured on the OSA and the selected optical mode for locking is identified. The region of injection locking and various other regions of dynamical behaviour between the lasers are observed on the ESA. The time trace information of the system is obtained from the HSO and performing the FFT (Fast Fourier Transform) of the time traces returns the power spectra. Using these tools, the similarities and differences between off-chip injection locking with an isolator, and on-chip mutual locking are examined. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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9 pages, 2488 KiB

Open AccessArticle

A Monolithically Integrated Laser-Photodetector Chip for On-Chip Photonic and Microwave Signal Generation

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Photonics 2019, 6(4), 102; https://doi.org/10.3390/photonics6040102 - 30 Sep 2019

Cited by 5 | Viewed by 3258

Abstract

An Indium-phosphide-based monolithically integrated photonic chip comprising of an amplified feedback laser (AFL) and a photodetector was designed and fabricated for on-chip photonic and microwave generation. Various waveforms including single tone, multi-tone, and chaotic signal generation were demonstrated by simply adjusting the injection [...] Read more.

An Indium-phosphide-based monolithically integrated photonic chip comprising of an amplified feedback laser (AFL) and a photodetector was designed and fabricated for on-chip photonic and microwave generation. Various waveforms including single tone, multi-tone, and chaotic signal generation were demonstrated by simply adjusting the injection currents applied to the controlling electrodes. The evolution dynamics of the photonic chip was characterized. Photonic microwave with frequency separation tunable from 26.3 GHz to 34 GHz, chaotic signal with standard bandwidth of 12 GHz were obtained. An optoelectronic oscillator (OEO) based on the integrated photonic chip was demonstrated without using any external electrical filter and photodetector. Tunable microwave outputs ranging from 25.5 to 26.4 GHz with single sideband (SSB) phase noise less than −90 dBc/Hz at a 10-kHz offset from the carrier frequency were realized. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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10 pages, 19287 KiB

Open AccessArticle

Optical Sideband Injection Locking Using Waveguide Based External Cavity Semiconductor Lasers for Narrow-Line, Tunable Microwave Generation

by

Md. Rezaul Hoque Khan

and

Md. Ashraful Hoque

Photonics 2019, 6(3), 81; https://doi.org/10.3390/photonics6030081 - 20 Jul 2019

Cited by 2 | Viewed by 3497

Abstract

The generation by optical injection locking of spectrally unadulterated microwave signals using waveguide based external cavity semiconductor lasers (WECSL) is demonstrated. A tunable frequency of 2–11 GHz, limited by the modulator’s bandwidth and the photodetector (PD), was created as proof-of-experiment by the injection [...] Read more.

The generation by optical injection locking of spectrally unadulterated microwave signals using waveguide based external cavity semiconductor lasers (WECSL) is demonstrated. A tunable frequency of 2–11 GHz, limited by the modulator’s bandwidth and the photodetector (PD), was created as proof-of-experiment by the injection locking of the two WESCLs. A single sideband (SSB) phase noise of −75 dBc/Hz from the generated carrier at 10 kHz offset and a phase noise variance at an optimum injection ratio region was 0.03 rad², corresponding to 1.7°, were observed. The main feature of this approach is the consolidation of the upsides of microwave generation at low phase noise with a broad tuning range and the capacity of hybrid photonic integration. In addition, the injection locking characteristics were used to determine the Q factor of the complicated optical cavities with unknown inner losses. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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10 pages, 1584 KiB

Open AccessFeature PaperArticle

Stability Boundaries in Laterally-Coupled Pairs of Semiconductor Lasers

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Photonics 2019, 6(2), 74; https://doi.org/10.3390/photonics6020074 - 25 Jun 2019

Cited by 6 | Viewed by 3344

Abstract

The dynamic behaviour of coupled pairs of semiconductor lasers is studied using normal-mode theory, applied to one-dimensional (slab) and two-dimensional (circular cylindrical) real index confined structures. It is shown that regions of stable behaviour depend not only on pumping rate and laser separation, [...] Read more.

The dynamic behaviour of coupled pairs of semiconductor lasers is studied using normal-mode theory, applied to one-dimensional (slab) and two-dimensional (circular cylindrical) real index confined structures. It is shown that regions of stable behaviour depend not only on pumping rate and laser separation, but also on the degree of guidance in the structures. Comparison of results between normal-mode and coupled-mode theories for these structures leads to the tentative conclusion that the accuracy of the latter is determined by the strength of self-overlap and cross-overlap of the symmetric and antisymmetric normal modes in the two lasers. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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8 pages, 1391 KiB

Open AccessArticle

Bias Current of Semiconductor Laser: An Unsafe Key for Secure Chaos Communication

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Photonics 2019, 6(2), 59; https://doi.org/10.3390/photonics6020059 - 29 May 2019

Cited by 8 | Viewed by 2809

Abstract

In this study, we have proposed and numerically demonstrated that the bias current of a semiconductor laser cannot be used as a key for optical chaos communication, using external-cavity lasers. This is because the chaotic carrier has a signature of relaxation oscillation, whose [...] Read more.

In this study, we have proposed and numerically demonstrated that the bias current of a semiconductor laser cannot be used as a key for optical chaos communication, using external-cavity lasers. This is because the chaotic carrier has a signature of relaxation oscillation, whose period can be extracted by the first side peak of the carrier’s autocorrelation function. Then, the bias current can be approximately cracked, according to the well-known relationship between the bias current and relaxation period of a solitary laser. Our simulated results have shown that the cracked current eavesdropper could successfully crack an encrypted message, by means of a unidirectional locking injection or a bidirectional coupling. In addition, the cracked bias current was closer to the real value as the bias current increased, meaning that a large bias current brought a big risk to the security. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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11 pages, 2625 KiB

Open AccessArticle

Nonlinear Dynamics of Exclusive Excited-State Emission Quantum Dot Lasers Under Optical Injection

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Photonics 2019, 6(2), 58; https://doi.org/10.3390/photonics6020058 - 27 May 2019

Cited by 11 | Viewed by 2943

Abstract

We numerically investigate the nonlinear dynamic properties of an exclusive excited-state (ES) emission quantum dot (QD) laser under optical injection. The results show that, under suitable injection parameters, the ES-QD laser can exhibit rich nonlinear dynamical behaviors, such as injection locking (IL), period [...] Read more.

We numerically investigate the nonlinear dynamic properties of an exclusive excited-state (ES) emission quantum dot (QD) laser under optical injection. The results show that, under suitable injection parameters, the ES-QD laser can exhibit rich nonlinear dynamical behaviors, such as injection locking (IL), period one (P1), period two (P2), multi-period (MP), and chaotic pulsation (CP). Through mapping these dynamic states in the parameter space of the frequency detuning and the injection coefficient, it can be found that the IL occupies a wide region and the dynamic evolution routes appear in multiple forms. Via permutation entropy (PE) calculation to quantify the complexity of the CP state, the parameter range for acquiring the chaos with high complexity can be determined. Moreover, the influence of the linewidth enhancement factor (LEF) on the dynamical state of the ES-QD laser is analyzed. With the increase of the LEF value, the chaotic area shrinks (expands) in the negative (positive) frequency detuning region, and the IL region gradually shifts towards the negative frequency detuning. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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14 pages, 1744 KiB

Open AccessArticle

Investigation of the Effect of Intra-Cavity Propagation Delay in Secure Optical Communication Using Chaotic Semiconductor Lasers

by

Elumalai Jayaprasath

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Zheng-Mao Wu

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Sivaraman Sivaprakasam

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Photonics 2019, 6(2), 49; https://doi.org/10.3390/photonics6020049 - 09 May 2019

Cited by 5 | Viewed by 2805

Abstract

The influence of intra-cavity propagation delay in message encoding and decoding using chaotic semiconductor lasers is numerically investigated. A message is encoded at the transmitter laser by a chaos shift keying scheme and is decoded at the receiver by comparing its output with [...] Read more.

The influence of intra-cavity propagation delay in message encoding and decoding using chaotic semiconductor lasers is numerically investigated. A message is encoded at the transmitter laser by a chaos shift keying scheme and is decoded at the receiver by comparing its output with the transmitter laser. The requisite intra-cavity propagation delay in achieving synchronization of optical chaos is estimated by cross-correlation analysis between the transmitter and receiver lasers’ output. The effect of intra-cavity propagation delay on the message recovery has been analyzed from the bit error rate performance. It is found that despite the intra-cavity propagation delay magnitude being less, it has an impact on the quality of message recovery. We also examine the dependency of injection rate, frequency detuning, modulation depth and bit rate on intra-cavity propagation delay and associated message recovery quality. We found that the communication performance has been adequately improved after incorporating intra-cavity propagation delay correction in the synchronization system. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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7 pages, 2622 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Exploiting the Nonlinear Dynamics of Optically Injected Semiconductor Lasers for Optical Sensing

by

Maria S. Torre

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Cristina Masoller

Photonics 2019, 6(2), 45; https://doi.org/10.3390/photonics6020045 - 24 Apr 2019

Cited by 4 | Viewed by 3162

Abstract

Optically injected semiconductor lasers are known to display a rich variety of dynamic behaviours, including the emission of excitable pulses, and of rare giant pulses (often referred to as optical rogue waves). Here, we use a well-known rate equation model to explore the [...] Read more.

Optically injected semiconductor lasers are known to display a rich variety of dynamic behaviours, including the emission of excitable pulses, and of rare giant pulses (often referred to as optical rogue waves). Here, we use a well-known rate equation model to explore the combined effect of excitability and extreme pulse emission, for the detection of variations in the strength of the injected field. We find parameter regions where the laser always responds to a perturbation by emitting an optical pulse whose amplitude is above a pre-defined detection threshold. We characterize the sensing capability of the laser in terms of the amplitude and the duration of the perturbation. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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12 pages, 2397 KiB

Open AccessArticle

Mode Suppression in Injection Locked Multi-Mode and Single-Mode Lasers for Optical Demultiplexing

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Photonics 2019, 6(1), 27; https://doi.org/10.3390/photonics6010027 - 08 Mar 2019

Cited by 13 | Viewed by 3431

Abstract

Optical injection locking has been demonstrated as an effective filter for optical communications. These optical filters have advantages over conventional passive filters, as they can be used on active material, allowing them to be monolithically integrated onto an optical circuit. We present an [...] Read more.

Optical injection locking has been demonstrated as an effective filter for optical communications. These optical filters have advantages over conventional passive filters, as they can be used on active material, allowing them to be monolithically integrated onto an optical circuit. We present an experimental and theoretical study of the optical suppression in injection locked Fabry–Pérot and slotted Fabry–Pérot lasers. We consider both single frequency and optical comb injection. Our model is then used to demonstrate that improving the Q factor of devices increases the suppression obtained when injecting optical combs. We show that increasing the Q factor while fixing the device pump rate relative to threshold causes the locking range of these demultiplexers to asymptotically approach a constant value. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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Review

Jump to: Editorial, Research

10 pages, 1767 KiB

Open AccessReview

Routes to Chaos of a Semiconductor Laser Subjected to External Optical Feedback: A Review

by

Alexandre Locquet

Photonics 2020, 7(1), 22; https://doi.org/10.3390/photonics7010022 - 05 Mar 2020

Cited by 11 | Viewed by 3228

Abstract

This paper reviews experimental investigations of the route to chaos of a semiconductor laser subjected to optical feedback from a distant reflector. When the laser is biased close to threshold, as the feedback strength is increased, an alternation between stable continuous wave (CW) [...] Read more.

This paper reviews experimental investigations of the route to chaos of a semiconductor laser subjected to optical feedback from a distant reflector. When the laser is biased close to threshold, as the feedback strength is increased, an alternation between stable continuous wave (CW) behavior and irregular, chaotic fluctuations, involving numerous external-cavity modes, is observed. CW operation occurs on an external-cavity mode whose optical frequency is significantly lower than that of the solitary laser. The scenario is significantly different for larger currents as the feedback level is increased. At low feedback, the laser displays periodic or quasiperiodic behavior, mostly around external-cavity modes whose frequency is slightly larger than that of the solitary laser. As the feedback level increases, the RF and optical frequencies involved progressively lock until complete locking is achieved in a mixed external-cavity mode state. In this regime, the optical intensity and voltage oscillate at a frequency that is also equal to the optical frequency spacing between the modes participating in the dynamics. For even higher feedback, the locking cannot be maintained and the laser displays fully developed coherence collapse. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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33 pages, 11871 KiB

Open AccessEditor’s ChoiceReview

Hybrid Integrated Semiconductor Lasers with Silicon Nitride Feedback Circuits

Photonics 2020, 7(1), 4; https://doi.org/10.3390/photonics7010004 - 21 Dec 2019

Cited by 82 | Viewed by 14432

Abstract

Hybrid integrated semiconductor laser sources offering extremely narrow spectral linewidth, as well as compatibility for embedding into integrated photonic circuits, are of high importance for a wide range of applications. We present an overview on our recently developed hybrid-integrated diode lasers with feedback [...] Read more.

Hybrid integrated semiconductor laser sources offering extremely narrow spectral linewidth, as well as compatibility for embedding into integrated photonic circuits, are of high importance for a wide range of applications. We present an overview on our recently developed hybrid-integrated diode lasers with feedback from low-loss silicon nitride (Si

_{3}

N

_{4}

in SiO

_{2}

) circuits, to provide sub-100-Hz-level intrinsic linewidths, up to 120 nm spectral coverage around a 1.55

μ

m wavelength, and an output power above 100 mW. We show dual-wavelength operation, dual-gain operation, laser frequency comb generation, and present work towards realizing a visible-light hybrid integrated diode laser. Full article

(This article belongs to the Special Issue Semiconductor Laser Dynamics: Fundamentals and Applications)

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