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Abstract A coupled class‐B laser system is presented to obtain a nonlinear emitter. Its bistability was theoretically predicted, and numerically illustrated to demonstrate by a typical bistable curve diagram. The bistable system exhibits some typical nonlinear dynamic behaviours, such as hyperchaos, quasi‐period as well as coexistent scenarios, and shows a route to a single‐period away from hyperchaos. The hyperchaotic states are diagnosed to find by Lyapunov exponent. The hyperchaotic four‐scroll strange attractor was illustrated to be characterized by ergodicity, complexity, and randomness. The result has a reference value for a bistable optical device, a hyperchaotic emitter, and their applications.

The laser frequency stabilization technology is very important in the development of laser applications, and the improvement of this technology has tend to further expectations for portability and low cost, in addition to the realization of strict frequency control. In this context, we construct a dual-cavity laser frequency stabilization system based on an intracavity dual-mode self-reference mechanism. With this approach, we achieve remarkable results with a laser frequency drift of about 6.6 kHz and an Allen deviation (ADEV) of 10−13 levels over an integration time scale from 0.01 s to 1000 s. Notably, the solution achieves one of the best results without the need for an external reference structure. This work provides a way to realize wavelength-stabilized laser sources by interlocking two DFB lasers. This approach is distinguished by its simplicity and cost-effectiveness, making it a promising option for a variety of applications outside of the laboratory environment.

This work presents a stable and reliable turnkey continuous-wave laser system for a Yb/Ba multispecies trapped-ion quantum computer. The compact and rack-mountable optics system exhibits high robustness, operating over a year without realignment, regardless of temperature changes in the laboratory. The overall optical system is divided into a few isolated modules interconnected by optical fibers for easy maintenance. The light sources are frequency-stabilized by comparing their frequencies with two complementary references: 1) a commercial Fizeau wavelength meter and 2) a high-finesse optical cavity. This scheme enables automatic frequency stabilization for days with a sub-MHz precision.

Laser diodes are widely used in research and industrial applications in areas such as measurements, communications and health. In most of these applications, stability in the emitted light power is required. This can be realized by modifying the internal parameters, such as the current supply, by using an analog automatic power control (APC). This research presents the design and analysis of a feedback laser driver (digital APC system) based on a proportionall–integral (PI) controller. The controller’s theoretical design acting on the supply current in a laser was obtained by algebraically solving the general equations of a PI controller over a laser described as a steady-state system. The required steady-state model can be determined from the lightl–current curve obtained either from the laser data sheet or experimentally. A posterior numerical analysis shows that the proportional gain of the PI controller is only limited numerically by the reciprocal of the slope efficiency of the laser when the characteristic time of the system is greater than the sampling period. Finally, the APC model was tested in an experimental setting using a laser diode ADL-65052TL at several temperatures. The results show that the proposed relations for the proportional gain and the integral time are valid, achieving the desired power stability with a drift of less than 0.1%.

To increase the spectral efficiency of coherent communication systems, lasers with ever-narrower linewidths are required as they enable higher-order modulation formats with lower bit-error rates. In particular, semiconductor lasers are a key component due to their compactness, low power consumption, and potential for mass production. In field-testing scenarios their output is coupled to a fiber, making them susceptible to external optical feedback (EOF). This has a detrimental effect on its stability, thus it is traditionally countered by employing, for example, optical isolators and angled output waveguides. In this work, EOF is explored in a novel way with the aim to reduce and stabilize the laser linewidth. EOF has been traditionally studied in the case where it is applied to only one side of the laser cavity. In contrast, this work gives a generalization to the case of feedback on both sides. It is implemented using photonic components available via generic foundry platforms, thus creating a path towards devices with high technology-readiness level. Numerical results shows an improvement in performance of the double-feedback case with respect to the single-feedback case. In particularly, by appropriately selecting the phase of the feedback from both sides, a broad stability regime is discovered. This work paves the way towards low-cost, integrated and stable narrow-linewidth integrated lasers.

We present a detailed frequency noise characterization of an ultrafast diode-pumped solid-state laser operating at 25-GHz repetition rate. The laser is based on the gain material Er:Yb:glass and operates at a wavelength of 1.55 μm. Using a beating measurement with an ultralow-noise continuous-wave laser in combination with a dedicated electrical scheme, we measured the frequency noise properties of an optical mode of the 25-GHz laser, of its repetition rate and indirectly of its carrier-envelope offset (CEO) signal without detecting the CEO frequency by the standard approach of nonlinear interferometry. We observed a strong anticorrelation between the frequency noise of the indirect CEO signal and of the repetition rate in our laser, leading to optical modes with a linewidth below 300 kHz in the free-running laser (at 100-ms integration time), much narrower than the individual contributions of the carrier envelope offset and repetition rate. We explain this behavior by the presence of a fixed point located close to the optical carrier in the laser spectrum for the dominant noise source.

In this paper, we propose our observation, analysis, and alleviation method of the beat frequency fluctuation in short-cavity dual-polarization distributed Bragg reflector (DBR) fiber grating laser sensor in time and frequency domain. According to our observation, beat frequency fluctuation varies from 8 to 800 kHz under different pump power. Research shows frequency domain beat signal linewidth broadening aggravates beat frequency fluctuation due to time domain irregular self-pulsation effect. By introducing self-injection into laser cavity as an auxiliary pump laser with a circulator, self-pulsation effect in DBR fiber laser sensor can be greatly suppressed, resulting in the compression of frequency domain beat signal linewidth as well as the stabilization of beat frequency fluctuation. Experimental results demonstrate that beat frequency fluctuation can be greatly reduced from 800 to 8 kHz within 1 h through self-injection, which is significant for high-accurate sensing.

Absolute distance measurement is a field of research with a large variety of applications. Laser triangulation is a well-tested and developed technique using geometric relations to calculate the absolute distance to an object. The advantages of laser triangulation include its simple and cost-effective setup with yet a high achievable accuracy and resolution in short distances. A main problem of the technology is that even small changes of the optomechanical setup, e.g., due to thermal expansion, lead to significant measurement errors. Therefore, in this work, we introduce an optical setup containing only a beam splitter and a mirror, which splits the laser into a measurement beam and a reference beam. The reference beam can then be used to compensate for different error sources, such as laser beam dithering or shifts of the measurement setup due to the thermal expansion of the components. The effectiveness of this setup is proven by extensive simulations and measurements. The compensation setup improves the deviation in static measurements by up to 75%, whereas the measurement uncertainty at a distance of 1 m can be reduced to 85 μm. Consequently, this compensation setup can improve the accuracy of classical laser triangulation devices and make them more robust against changes in environmental conditions.

In the present work, the effect of gamma radiation on the performance of different types of erbium-doped fibers (EDFs) when they are used in a fiber ring cavity (FRC) configuration is studied. Several pieces of commercial EDF are gamma-ray irradiated with different doses to evaluate the output power variations over time. The influence of different doses, from 150 Gy to 1000 Gy, over the output power level measurement and their amplified spontaneous emission (ASE) are experimentally evaluated both in the C and L bands. By using an FRC configuration we can detect the presence of gamma radiation. We can also estimate the irradiation doses applied to EDFs by measuring the slope of the short-term emission power.

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.

Continuous-wave (CW) broadband in the C- and L-band wavelength regions is demonstrated by introducing a highly nonlinear fiber (HNLF) in an erbium-doped fiber ring laser (EDFRL). A broadband spectrum of ~ 39 nm in the L-band and ~ 21 nm in the C-band were obtained at pump powers as low as ~ 200 mW with appropriate optimizations. Demultiplexed output from the broadband generated in the C-band region is tested for wavelength and power stability for consideration as a suitable source for various applications. The wavelength and power fluctuations have been observed to be at most ~ 0.02 nm and ~ 0.3 dBm, respectively.