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9 pages, 2556 KiB

Open AccessArticle

Development of a High-Power Surface Grating Tunable Distributed-Feedback Bragg Semiconductor Laser Based on Gain-Coupling Effect

by Xin Li, Lei Liang, Li Qin, Yuxin Lei, Peng Jia, Hui Tang, Changjin Yang, Yongyi Chen, Yubing Wang, Yu Song, Cheng Qiu, Chuantao Zheng and Lijun Wang

Appl. Sci. 2022, 12(9), 4498; https://doi.org/10.3390/app12094498 - 29 Apr 2022

Cited by 4 | Viewed by 2379

Abstract

Lasers used for space communication, lidar, and laser detection in space-air-ground integration applications typically use a traditional 1550 nm band tunable distributed-feedback Bragg (DFB) semiconductor laser. This has low output power, complex fabrication process, and high fabrication cost. In this paper, we present [...] Read more.

Lasers used for space communication, lidar, and laser detection in space-air-ground integration applications typically use a traditional 1550 nm band tunable distributed-feedback Bragg (DFB) semiconductor laser. This has low output power, complex fabrication process, and high fabrication cost. In this paper, we present a gain-coupled surface grating-based 1550 nm DFB semiconductor laser that can be fabricated without the use of secondary epitaxial growth techniques or high-precision lithography. The periodic electrical injection is used to achieve a gain coupling effect. A tapered waveguide is added to achieve a high output power, and the use of AlGaInAs multiple quantum wells in the active region reduces the linewidth of the laser. A continuous-wave (CW)output power of 401.5 mW is achieved at 20 °C, the maximum side mode rejection ratio exceeds 55 dB, the measured 3 dB linewidth is 18.86 MHz, and the stable single-mode output with a quasi-continuous tuning range of 6.156 nm near 1550 nm from 10 °C to 50 °C. This simple preparation method, low cost, excellent performance, and stable tunable laser have extremely high commercial value in applications such as space communication, lidar, and laser detection. Full article

(This article belongs to the Special Issue Research and Application of Semiconductor Lasers)

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11 pages, 4385 KiB

Open AccessArticle

Degree of Polarization of High-Power Laser Diodes: Modeling and Statistical Experimental Investigation

by Alberto Maina, Claudio Coriasso, Simone Codato and Roberto Paoletti

Appl. Sci. 2022, 12(7), 3253; https://doi.org/10.3390/app12073253 - 23 Mar 2022

Cited by 5 | Viewed by 2350

Abstract

A statistical experimental investigation of the characteristic changes associated with the degree-of-polarization reduction of high-power laser diodes is reported. A simple model accounting for the stress-induced degree-of-polarization changes through the photoelastic effect is introduced to qualitatively support the experimental results. Functional characteristics addressed [...] Read more.

A statistical experimental investigation of the characteristic changes associated with the degree-of-polarization reduction of high-power laser diodes is reported. A simple model accounting for the stress-induced degree-of-polarization changes through the photoelastic effect is introduced to qualitatively support the experimental results. Functional characteristics addressed in the investigation are the threshold current, the slope efficiency, the polarization-resolved far field and near field, and the beam parameter product. Model outcomes and measured parameters related to different degree-of-polarization values have proven very useful for device optimization aimed to polarization multiplexing applications. Full article

(This article belongs to the Special Issue Research and Application of Semiconductor Lasers)

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12 pages, 793 KiB

Open AccessArticle

Effects of Timing Noise on Square-Wave Optoelectronic Oscillators

by David S. Citrin

Appl. Sci. 2021, 11(24), 12038; https://doi.org/10.3390/app112412038 - 17 Dec 2021

Cited by 1 | Viewed by 2095

Abstract

Optoelectronic oscillators produce microwave-modulated optical beams without external modulation. The most commonly studied types produces narrow-band output, i.e., optical output modulated by a sinusoid, in which case phase noise determines key figures of merit that limit device performance. Nonetheless, other types of modulated [...] Read more.

Optoelectronic oscillators produce microwave-modulated optical beams without external modulation. The most commonly studied types produces narrow-band output, i.e., optical output modulated by a sinusoid, in which case phase noise determines key figures of merit that limit device performance. Nonetheless, other types of modulated signals have been exhibited by optoelectronic oscillators, including square waves. In this work we provide a theoretical treatment of the power spectral density of a microwave self-modulated optical periodic, but non-sinusoidal, oscillator in the presence of timing noise (as phase noise is only defined for a single sinusoid) and focus on the case of square waves. We consider the effects of timing noise on the power spectral density and autocorrelation function of the modulation signal. Full article

(This article belongs to the Special Issue Research and Application of Semiconductor Lasers)

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10 pages, 2882 KiB

Open AccessArticle

16.3 W Peak-Power Pulsed All-Diode Laser Based Multi-Wavelength Master-Oscillator Power-Amplifier System at 964 nm

by Thi Nghiem Vu, Tran Quoc Tien, Bernd Sumpf, Andreas Klehr, Jörg Fricke, Hans Wenzel and Günther Tränkle

Appl. Sci. 2021, 11(18), 8608; https://doi.org/10.3390/app11188608 - 16 Sep 2021

Cited by 2 | Viewed by 2553

Abstract

An all-diode laser-based master oscillator power amplifier (MOPA) configuration for the generation of ns-pulses with high peak power, stable wavelength and small spectral line width is presented. The MOPA emits alternating at two wavelengths in the spectral range between 964 nm and 968 [...] Read more.

An all-diode laser-based master oscillator power amplifier (MOPA) configuration for the generation of ns-pulses with high peak power, stable wavelength and small spectral line width is presented. The MOPA emits alternating at two wavelengths in the spectral range between 964 nm and 968 nm, suitable for the detection of water vapor by absorption spectroscopy. The monolithic master oscillator (MO) consists of two slightly detuned distributed feedback laser branches, whose emission is combined in a Y-coupler. The two emission wavelengths can be adjusted by varying the current or temperature to an absorption line and to a non-absorbing region. The power amplifier (PA) consists of a ridge-waveguide (RW) section and a tapered section, monolithically integrated within one chip. The RW section of the PA acts as an optical gate and converts the continuous wave input beam emitted by the MO into a sequence of short optical pulses, which are subsequently amplified by the tapered section to boost the output power. For a pulse width of 8 ns, a peak power of 16.3 W and a side mode suppression ratio of more than 37 dB are achieved at a repetition rate of 25 kHz. The measured spectral width of 10 pm, i.e., 0.1 cm⁻¹, is limited by the resolution of the optical spectrum analyzer. The generated pulses emitting alternating at two wavelengths can be utilized in a differential absorption light detection and ranging system. Full article

(This article belongs to the Special Issue Research and Application of Semiconductor Lasers)

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8 pages, 1570 KiB

Open AccessArticle

Locking Phenomena in Semiconductor Lasers near Threshold with Optical Feedback and Sinusoidal Current Modulation

by Jordi Tiana-Alsina and Cristina Masoller

Appl. Sci. 2021, 11(17), 7871; https://doi.org/10.3390/app11177871 - 26 Aug 2021

Cited by 4 | Viewed by 2056

Abstract

The dynamics of semiconductor lasers with optical feedback and current modulation has been extensively studied, and it is, by now, well known that the interplay of modulation and feedback can produce a rich variety of nonlinear phenomena. Near threshold, in the so-called low [...] Read more.

The dynamics of semiconductor lasers with optical feedback and current modulation has been extensively studied, and it is, by now, well known that the interplay of modulation and feedback can produce a rich variety of nonlinear phenomena. Near threshold, in the so-called low frequency fluctuations regime, the intensity emitted by the laser, without modulation, exhibits feedback-induced spikes, which occur at irregular times. When the laser current is sinusoidally modulated, under appropriate conditions, the spikes lock to the modulation and become periodic. In previous works, we studied experimentally the locked behavior and found sub-harmonic locking (regular spike timing such that a spike is emitted every two or three modulation cycles), but we did not find spikes with regular timing, emitted every modulation cycle. To understand why 1:1 regular locking was not observed, here, we perform simulations of the well-known Lang–Kobayashi model. We find a good qualitative agreement with the experiments: with small modulation amplitudes, we find wide parameter regions in which the spikes are sub-harmonically locked to the modulation, while 1:1 locking occurs at much higher modulation amplitudes. Full article

(This article belongs to the Special Issue Research and Application of Semiconductor Lasers)

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12 pages, 2048 KiB

Open AccessArticle

Optical Frequency Comb Expansion Using Mutually Injection-Locked Gain-Switched Lasers

by Prajwal D. Lakshmijayasimha, Prince M. Anandarajah, Pascal Landais and Aleksandra Kaszubowska-Anandarajah

Appl. Sci. 2021, 11(15), 7108; https://doi.org/10.3390/app11157108 - 31 Jul 2021

Cited by 8 | Viewed by 2780

Abstract

We propose a novel scheme for the expansion and comb densification of gain-switched optical frequency combs (GS-OFC). The technique entails mutual injection locking of two gain-switched lasers with a common master to generate a wider bandwidth OFC. Subsequently, the OFC is further expanded [...] Read more.

We propose a novel scheme for the expansion and comb densification of gain-switched optical frequency combs (GS-OFC). The technique entails mutual injection locking of two gain-switched lasers with a common master to generate a wider bandwidth OFC. Subsequently, the OFC is further expanded and/or densified using a phase modulator with optimum drive conditions. We experimentally demonstrate the generation of an OFC with 45 highly correlated lines separated by 6.25 GHz with an expansion factor ~3. In addition, operating in comb densification mode, the channel spacing of the OFC is tuned from 6.25 GHz to 390.625 MHz. Finally, a detailed characterization of the lines, across the entire expanded comb, is reported highlighting the excellent spectral purity with linewidths of ~40 kHz, a relative intensity noise better than −152 dB/Hz, and a high degree of phase correlation between the comb lines. The proposed method is simple, highly flexible and the architecture is suitable for photonic integration, all of which make such an OFC extremely attractive for the employment in a multitude of applications. Full article

(This article belongs to the Special Issue Research and Application of Semiconductor Lasers)

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14 pages, 571 KiB

Open AccessFeature PaperArticle

Reduced Dimensionality Multiphysics Model for Efficient VCSEL Optimization

by Alberto Gullino, Alberto Tibaldi, Francesco Bertazzi, Michele Goano and Pierluigi Debernardi

Appl. Sci. 2021, 11(15), 6908; https://doi.org/10.3390/app11156908 - 27 Jul 2021

Cited by 7 | Viewed by 2157

Abstract

The ICT scene is dominated by short-range intra-datacenter interconnects and networking, requiring high speed and stable operations at high temperatures. GaAs/AlGaAs vertical-cavity surface-emitting lasers (VCSELs) emitting at 850–980 nm have arisen as the main actors in this framework. Starting from our in-house 3D [...] Read more.

The ICT scene is dominated by short-range intra-datacenter interconnects and networking, requiring high speed and stable operations at high temperatures. GaAs/AlGaAs vertical-cavity surface-emitting lasers (VCSELs) emitting at 850–980 nm have arisen as the main actors in this framework. Starting from our in-house 3D fully comprehensive VCSEL solver VENUS, in this work we present the possibility of downscaling the dimensionality of the simulation, ending up with a multiphysics 1D solver (D1ANA), which is shown to be capable of reproducing the experimental data very well. D1ANA is then extensively applied to optimize high-temperature operation, by modifying cavity detuning and distributed Bragg’s reflector lengths. Full article

(This article belongs to the Special Issue Research and Application of Semiconductor Lasers)

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Review

Jump to: Research

29 pages, 2267 KiB

Open AccessReview

Semiconductor Laser Linewidth Theory Revisited

by Hans Wenzel, Markus Kantner, Mindaugas Radziunas and Uwe Bandelow

Appl. Sci. 2021, 11(13), 6004; https://doi.org/10.3390/app11136004 - 28 Jun 2021

Cited by 19 | Viewed by 4104

Abstract

More and more applications require semiconductor lasers distinguished not only by large modulation bandwidths or high output powers, but also by small spectral linewidths. The theoretical understanding of the root causes limiting the linewidth is therefore of great practical relevance. In this paper, [...] Read more.

More and more applications require semiconductor lasers distinguished not only by large modulation bandwidths or high output powers, but also by small spectral linewidths. The theoretical understanding of the root causes limiting the linewidth is therefore of great practical relevance. In this paper, we derive a general expression for the calculation of the spectral linewidth step by step in a self-contained manner. We build on the linewidth theory developed in the 1980s and 1990s but look from a modern perspective, in the sense that we choose as our starting points the time-dependent coupled-wave equations for the forward and backward propagating fields and an expansion of the fields in terms of the stationary longitudinal modes of the open cavity. As a result, we obtain rather general expressions for the longitudinal excess factor of spontaneous emission (K-factor) and the effective

α

-factor including the effects of nonlinear gain (gain compression) and refractive index (Kerr effect), gain dispersion, and longitudinal spatial hole burning in multi-section cavity structures. The effect of linewidth narrowing due to feedback from an external cavity often described by the so-called chirp reduction factor is also automatically included. We propose a new analytical formula for the dependence of the spontaneous emission on the carrier density avoiding the use of the population inversion factor. The presented theoretical framework is applied to a numerical study of a two-section distributed Bragg reflector laser. Full article

(This article belongs to the Special Issue Research and Application of Semiconductor Lasers)

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