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The present paper is concerned with the analytical and numerical investigation of the dynamics of a broad-area vertical-cavity surface-emitting laser (VCSEL). It is shown that the adiabatic polarization elimination does not affect the modulation instability developing in the system. The efficiency of the method of external injection at different shapes of the pump current profile is verified. It is shown that for effective stabilization by optical injection beam with minimum amplitude it is necessary to use pump current profiles with smoother edges. [ABSTRACT FROM AUTHOR]

Frequency combs are powerful tools for many applications and high performances are achieved by stabilizing these lasers. For operation in the mid‐infrared, quantum cascade lasers (QCL) are ideal candidates as they present numerous advantages. However, stabilized QCL‐combs lack a detailed characterization of their noise properties due to the sensitivity limits of current analyzing techniques. To overcome these challenges, what is believed to be the first tightly locked dual QCL‐comb system is developed. Its use is twofold. First, phase noise analysis of the dual‐comb signal shows residual phase noise below 600 mrad for all comb lines, and the comb coherence as well as the performances of the repetition frequency locking mechanism is characterized. Second, coherent averaging with a 7 × 105 Hz1/2 figure‐of‐merit system is demonstrated, which is compatible with high‐precision spectroscopy. [ABSTRACT FROM AUTHOR]

A robust and compact blue optical frequency reference within blue region was designed. A 40‐mW tellurium‐stabilized single‐frequency blue diode laser in external cavity was designed with an absorption spectroscopy method based on tellurium molecular transitions. Furthermore, the uncertainty of the frequency stabilization can be pushed to 2 × 10−9 at a 10‐s integration time. In addition, the correspondence frequency instability was 1.3 MHz when the laser wavelength was 445.75 nm. This study indicates that high‐stability frequency reference within the blue region can be achieved with an external cavity diode laser as opposed to the diode‐pumped frequency‐doubled solid‐state laser. [ABSTRACT FROM AUTHOR]

The stabilization and manipulation of laser frequency by means of an external cavity are nearly ubiquitously used in fundamental research and laser applications. While most of the laser light transmits through the cavity, in the presence of some back-scattered light from the cavity to the laser, the self-injection locking effect can take place, which locks the laser emission frequency to the cavity mode of similar frequency. The self-injection locking leads to dramatic reduction of laser linewidth and noise. Using this approach, a common semiconductor laser locked to an ultrahigh-Q microresonator can obtain sub-Hertz linewidth, on par with state-of-the-art fiber lasers. Therefore it paves the way to manufacture high-performance semiconductor lasers with reduced footprint and cost. Moreover, with high laser power, the optical nonlinearity of the microresonator drastically changes the laser dynamics, offering routes for simultaneous pulse and frequency comb generation in the same microresonator. Particularly, integrated photonics technology, enabling components fabricated via semiconductor CMOS process, has brought increasing and extending interest to laser manufacturing using this method. In this article, we present a comprehensive tutorial on analytical and numerical methods of laser self-injection locking, as well a review of most recent theoretical and experimental achievements. [ABSTRACT FROM AUTHOR]

Keywords: Nanopositioning- and nanomeasuring machines; optical frequency comb; He-Ne laser; traceability; laser stabilization; Nanopositionier- und Nanomessmaschinen; Optische Frequenzkämme; He-Ne Laser; Rückführbarkeit; Laserstabilisierung EN Nanopositioning- and nanomeasuring machines optical frequency comb He-Ne laser traceability laser stabilization DE Nanopositionier- und Nanomessmaschinen Optische Frequenzkämme He-Ne Laser Rückführbarkeit Laserstabilisierung 687 703 17 09/26/22 20221001 NES 221001 1 Introduction The rapid development and increasing impact of nanotechnology in research and industry entails the application of new fabrication approaches and characterization tools that allow to manipulate, characterize and image three dimensional nanostructures with (sub)nanometer precision and increasing scanning speed over several tens to hundreds millimeters measurement range [[1]], [[2]], [[3]], [[4]], [[5]]. To lock the repetition rate HT ht to the RF-reference its fourth harmonic is mixed with the fixed frequency output of a phase-locked oscillator (PLO) [[33]]. The He-Ne lasers are part of a compact, enclosed laser module that contains three gas lasers stabilized with a two-mode-comparison technique [[22]] as well as the laser control and stabilization electronics. The iodine-stabilized He-Ne laser indicates a HT ht - dependence as described in [[47]]. [Extracted from the article]

Future space-based geodesy missions such as the Mass Change Mission and the Next Generation Gravity Mission are expected to rely on laser ranging as their primary instrument. Short-term laser frequency stability has previously been achieved on the GRACE Follow On mission by stabilizing the lasers to an optical cavity. The development of a technique to provide long-term laser frequency stability is expected to be required. We have previously demonstrated a technique to track long-term frequency changes by using measurements of the optical cavity's free spectral range. In this paper, we calibrate this technique to absolute frequency by using an atomic reference. We have also validated an approach for on-ground calibration to allow the absolute frequency to be determined whilst in orbit. [ABSTRACT FROM AUTHOR]

Integrating photonics with CMOS electronics in silicon is essential to enable chip-scale, electronic-photonic systems that will revolutionize classical and quantum communication and computing systems. However, the lack of an on-silicon isolator, capable of blocking unwanted back reflections and ensuring the stable operation of the laser, precluded many previous demonstrations from providing single-chip solutions. For most optical systems employing a laser, magneto-optic isolators have been indispensable, but such isolators are incompatible with silicon. To stabilize on-chip lasers, reflections-cancellation circuits were proposed as a way to reduce the reflections going back to the laser. Yet, a stable laser against time-varying back reflections was never demonstrated. Here we demonstrate a stable quantum well-distributed feedback (QWDFB) laser against slowly time-varying reflections using a reflections-cancellation circuit (RCC) on a foundry-produced, silicon-photonic (SiP) chip. The optical spectrum and the relative intensity noise (RIN) of the laser when the RCC was running is comparable to when an isolator was used. By accurately locking the laser in a stable optical feedback regime, the RCC further enhances the QWDFB laser performance by reducing its linewidth by a factor of 100, down to 3 kHz. Both results are enabled using novel techniques in the design, calibration, tuning, and control of the proposed SiP RCC. The optical insertion loss of the RCC is less than 1.5 dB for reflections smaller than −20 dB and can yield isolation ranges of up to 64 dB. Our device paves the way towards the mass production of fully integrated, low-cost electronic-photonic silicon chips without attaching magneto-optic isolators between the laser and the SiP chip. [ABSTRACT FROM AUTHOR]

Controlling the delivery of multi-terawatt and petawatt laser pulses to final focus, both in position and angle, is critical to many laser applications such as optical guiding, laser–plasma acceleration, and laser-produced secondary radiation. We present an online, non-destructive laser diagnostic, capable of measuring the transverse position and pointing angle at focus. The diagnostic is based on a unique double-surface-coated wedged-mirror design for the final steering optic in the laser line, producing a witness beam highly correlated with the main beam. By propagating low-power kilohertz pulses to focus, we observed spectra of focus position and pointing angle fluctuations dominated by frequencies below 70 Hz. The setup was also used to characterize the excellent position and pointing angle correlation of the 1 Hz high-power laser pulses to this low-power kilohertz pulse train, opening a promising path to fast non-perturbative feedback concepts even on few-hertz-class high-power laser systems. [ABSTRACT FROM AUTHOR]

Lasers with high spectral purity can enable a diverse application space, including precision spectroscopy, coherent high‐speed communications, physical sensing, and manipulation of quantum systems. Already, meticulous design and construction of bench Fabry–Perot cavities has made possible dramatic achievements in active laser‐linewidth reduction, predominantly for optical‐atomic clocks. Yet, there is increasing demand for miniaturized laser systems operating with high performance in ambient environments. Here, a compact and robust photonic‐atomic laser comprising a 2.5 centimeter long, 20 000 finesse, monolithic Fabry–Perot cavity integrated with a micromachined rubidium vapor cell is presented. By leveraging the short‐time frequency stability of the cavity and the long‐time frequency stability of atoms, an ultranarrow‐linewidth laser that enables integration for extended measurements is realized. Specifically, the laser supports a fractional‐frequency stability of 1×10−13 at an averaging time of 20 millisecond, 7×10−13 at 300 second, an integrated linewidth of 25 Hz that results from thermal noise, frequency noise floor as low as 0.06 Hz2 Hz−1, and a passive vibration immunity as low as 10−10g−1. The present work explores hybrid laser systems with monolithic photonic and atomic packages based on physical design. [ABSTRACT FROM AUTHOR]

The capability of optical reference cavities to resist ambient thermal fluctuations is significant in ultrastable laser systems especially applying in transportable system and space station. To reduce the deterioration of long-term laser frequency stability induced by temperature variation, the thermal response of cavities is investigated. The simulation and analysis indicate that the use of multiple enclosing thermal shields with a low emissivity allows a larger thermal time constant. The quantitative functional relationships between the thermal time constant and the heat capacity and surface emissivity of the passive thermal shields are firstly obtained using FEA simulation. Based on these results, a temperature-insensitive cavity system is designed with a thermal time constant of approximately 680 h. According to the designed system, two different methods are used to evaluate the thermal performance. And mathematical expressions for the cavity temperature over time are obtained. The calculated thermal time constant is validated by the simulated results. The thermal sensitivity of the designed system is 4.1 × 10−11 and 1.3 × 10−5 when temperature variation period is 1 h and 24 h, respectively. The fractional length instability of the cavities induced by temperature fluctuation is 8.2 × 10−16 over an average time of 1 day, which can compete theoretically with fountain clocks. [ABSTRACT FROM AUTHOR]

Semiconductor mode-locked lasers can be used in a variety of applications ranging from multi-carrier sources for wavelength-division-multiplexed communication systems to time-base references for metrology. Their packaging in compact chip- or module-level systems remains, however, burdened by their strong sensitivity to back-reflections, quickly destroying the coherence of the mode-locking. Here, we investigate the stabilization of mode-locked lasers directly edge coupled to a silicon photonic integrated circuit, with the objective of moving isolators downstream to the output of the photonic circuit. A 2.77-kHz 3-dB RF linewidth, substantially improved compared to the 15.01 kHz of the free running laser, is obtained in the best case. Even in the presence of detrimental reflections from the photonic circuit, substantial linewidth reductions from 20 to 8.82 kHz, from 572 to 14.8 kHz, and from 1.5 MHz to 40 kHz are realized. [ABSTRACT FROM AUTHOR]

We propose a modeling methodology tailored to predicting the wavelength and power output from a distributed Bragg reflector laser for use in quantum measurements. The relationship between power, wavelength, current, and temperature is acquired with a genetic algorithm (GA). The function set and termination set for GA are determined from the physical mechanisms of laser current, temperature, and output performance. To verify the validity of the method, measured data are divided into a training group and a test group. The test results show that our models can accurately predict the value of power and wavelength at the given current and temperature, with the RMSE of 13.4 μW and 6.0 × 10-5 nm, respectively. This method can help enhance the output performance of a laser. [ABSTRACT FROM AUTHOR]

We demonstrate a passive, material-based athermalization of all-fiber architectures consisting of cascaded multimode-interference (MMI) devices. Specifically, the athermal MMI filter used for in-line thermo-optic compensation consists of a no-core multimode fiber, which is spliced between two single-mode fibers, and is partly covered with a polymer coating. The design of the temperature-compensation unit is straightforward and its fabrication is simple. The applicability of our approach is experimentally verified by fabricating wavelength-locked MMI lasers with a temperature sensitivity lower than 1.0 pm/°C, which is several times smaller than that achieved with other fiber-optic devices and is comparable to that targeted in silicon photonics. [ABSTRACT FROM AUTHOR]

We present a frequency stabilized laser at 2051 nm based on a versatile all-fibered stabilization setup. A modulation sideband locking technique is implemented to lock the laser at a controlled frequency detuning from the center of the CO R(30) transition envisaged for space-borne differential absorption lidar (DIAL) applications. This method relies on the use of a compact all-fibered gas reference cell that makes the setup robust and immune to mechanically induced optical misalignments. The gas cell is fabricated using a hollow-core photonic crystal fiber filled with pure CO at a low pressure of ~20 mbar and hermetically sealed at both ends by splices to silica fibers. Different configurations of this fibered cell have been developed and are presented. With this technique, frequency stabilities below 40 kHz at 1-s integration time and <100 kHz up to 1000-s averaging time were achieved for a laser detuning by around 1 GHz from the center of the CO transition. These stabilities are compliant with typical requirements for the reference seed source for a space CO DIAL. [ABSTRACT FROM AUTHOR]

Distributed feedback laser is widely used as the pump beam and probe beam in atomic physical and quantum experiments. As the frequency stability is a vital characteristic to the laser diode in these experiments, a saturated absorption frequency stabilization method assisted with the function of current and frequency is proposed. The relationship between the current and frequency is acquired based on the genetic programming (GP) algorithm. To verify the feasibility of the method, the frequency stabilization system is comprised of two parts that are modeling the relation between the current and frequency by GP and processing the saturated absorption signal. The results of the frequency stabilization experiment proved that this method can not only narrow the frequency searching range near the atomic line center but also compensate for the phase delay between the saturated absorption peak and the zero crossing point of the differential error signal. The reduced phase delay increases the locking probability and makes the wavelength drift only 0.015 pm/h, which converted to frequency drift is 7 MHz/h after frequency locking on the Rb absorption line. [ABSTRACT FROM AUTHOR]

Two diode lasers at 698 nm are separately locked to two independent optical reference cavities with a finesse of about 128,000 by the Pound-Drever-Hall method. The more accurate coefficient between voltage and frequency of the error signal is measured, with which quantitative evaluation of the effect of many noises on the frequency stability can be made much more conveniently. A temperature-insensitive method is taken to reduce the effect of residual amplitude modulation on laser frequency stability. With an active fiber noise cancellation, the optical heterodyne beat between two independent lasers shows that the linewidth of one diode laser reaches 1 Hz. The fractional Allan deviation removed linear frequency shift less than 30 mHz/s is below 2.6 × 10-15 with 1- to 100-s average time. [ABSTRACT FROM AUTHOR]

We investigate the effect of tunable filtered optical feedback on a commercial DFB laser edge coupled to a silicon photonic planar integrated circuit in which a tunable reflector has been implemented by means of a ring resonator-based add–drop multiplexer. Controlled optical feedback allows for fine-tuning of the laser oscillation frequency. Under certain conditions, it also allows suppression of bifurcation modes triggered by reflections occurring elsewhere on the chip. A semianalytical model describing laser dynamics under combined optical feedback from the input facet of the edge coupler and from the tunable on-chip reflector fits the measurements. Compensation of detrimental effects from reflections induced elsewhere on a transceiver chip may allow moving isolators downstream in future communications systems, facilitating direct hybrid laser integration in silicon photonic chips, provided a suitable feedback signal for a control system can be identified. Moreover, the optical frequency tuning at lower feedback levels can be used to form a rapidly tunable optical oscillator as part of an optical phase-locked loop, circumventing the problem of the thermal to free carrier effect crossover in the FM response of injection current-controlled semiconductor laser diodes. [ABSTRACT FROM PUBLISHER]

Optical frequency combs generated by quantum cascade lasers have recently been demonstrated in the mid and far infrared, but a detailed analysis of the possibility of a fine control of the emission to use them for high-resolution spectroscopy and metrology applications is still missing. In this manuscript the attempt of frequency stabilizing a mid-infrared quantum cascade laser comb (QCL-comb) against a metrological mid-infrared intracavity-difference-frequency-generated comb through a single phase-locking chain acting on the driving current is presented. Following a brief derivation, simple relations between the QCL-comb frequency parameters and optical quantities such as the refractive index have been found and used to observe how the locking affects the physics of the system. The conclusion is that the current locking essentially acts on the effective refractive index to reduce the offset fluctuations (common noise), but does not sensitively affect the group refractive index and the mode spacing. Nonetheless, the overall single QCL-comb tooth linewidth is reduced from 500 kHz down to values ranging from 1 to 23 kHz on a 40 ms time scale. [ABSTRACT FROM AUTHOR]

The need for highly performing and stable methods for mid-IR molecular sensing and metrology pushes towards the development of more and more compact and robust systems. Among the innovative solutions aimed at answering the need for stable mid-IR references are crystalline microresonators, which have recently shown excellent capabilities for frequency stabilization and linewidth narrowing of quantum cascade lasers with compact setups. In this work, we report on the first system for mid-IR high-resolution spectroscopy based on a quantum cascade laser locked to a CaF2 microresonator. Electronic locking narrows the laser linewidth by one order of magnitude and guarantees good stability over long timescales, allowing, at the same time, an easy way for finely tuning the laser frequency over the molecular absorption line. Improvements in terms of resolution and frequency stability of the source are demonstrated by direct sub-Doppler recording of a molecular line. [ABSTRACT FROM AUTHOR]

Narrow-linewidth lasers are key elements in optical metrology and spectroscopy. Spectral purity of these lasers determines accuracy of the measurements and quality of collected data. Solid state and fiber lasers are stabilized to relatively large and complex external optical cavities or narrow atomic and molecular transitions to improve their spectral purity. While this stabilization technique is rather generic, its complexity increases tremendously moving to longer wavelenghts, to the infrared (IR) range. Inherent increase of losses of optical materials at longer wavelengths hinders realization of compact, room temperature, high finesse IR cavities suitable for laser stabilization. In this paper, we report on demonstration of quantum cascade lasers stabilized to high-Q crystalline mid-IR microcavities. The lasers operating at room temperature in the 4.3-4.6 μm region have a linewidth approaching 10 kHz and are promising for on-chip mid-IR and IR spectrometers. [ABSTRACT FROM AUTHOR]

We demonstrate the short- and long-term stable operation of an all-polarization-maintained Fabry–Pérot cavity passively mode-locked fiber laser. The laser operates in an all-anomalous-dispersion solitonic regime. Laser stability is studied by a variety of measurements, which confirm the high stability of the laser in the temporal and spectral–both optical and electrical-domains. Pulse durations of 540 fs, period-relative time jitters of $\sim$0.015‰, and long-term uninterrumped operation with 0.4% variation (standard deviation) in the average output power are obtained. The highly stable operation of the laser oscillator was maintained after amplifying the laser output with a conventional EDFA. Pulse durations of $\sim$244 fs, period-relative time jitters of $\sim$0.019‰,  and an average output power of 20 mW were obtained after amplification, while maintaining the 100-dB signal-to-noise ratio of the laser oscillator measured at 500-Hz offset from the fundamental harmonic frequency. The theoretical validation of our experimental results is based on solutions of the Nonlinear Schrödinger Equation. We demonstrate that wavelength and z -position dependences of the active medium gain must be taken into account for an accurate correspondence with the experimental properties of the laser. [ABSTRACT FROM PUBLISHER]

A proof-of-concept experiment for fiber-based broad-area laser stabilization is experimentally demonstrated using coupling optics and a 1-nm wide, 98% reflectivity fiber Bragg grating. The output spectrum of a 3-W, 100- \mu \textm wide, 2-mm long commercial broad-area laser was narrowed by more than $10\times $ to 0.26-nm full-width half-max. In addition, the system showed 7%–13% enhanced output power. The system also shows potential for slow-axis beam quality improvement in the desired operating regime. A pump delivery fiber scheme is proposed for integration of the diode feedback into a pump system package for enhanced-brightness fiber pumping. [ABSTRACT FROM PUBLISHER]

We study theoretically and experimentally pulse fluctuations in a passively Q-switched laser caused by the thermal lens effect and design a special thermally insensitive cavity for an end-pumped passively Qswitched laser system with a composite crystal. We show experimentally that using a suitable cavity and maintaining the laser-system operation in the fundamental mode reduce the pulse fluctuations effectively. Under a pump power of 8 W, relative fluctuations of the pulse width and the repetition rate of this system are 2.3% and 3.5%, respectively. [ABSTRACT FROM AUTHOR]

We design a low-timing-jitter, repetition-rate-tunable, stretched-pulse passively mode-locked fiber laser by using a nonlinear amplifying loop mirror (NALM), a semiconductor saturable absorber mirror (SESAM), and a tunable optical delay line in the laser configuration. Low-timing-jitter optical pulses are stably produced when a SESAM and a 0.16 m dispersion compensation fiber are employed in the laser cavity. By inserting a tunable optical delay line between NALM and SESAM, the variable repetition-rate operation of a self-starting, passively mode-locked fiber laser is successfully demonstrated over a range from 49.65 to 50.47 MHz. The experimental results show that the newly designed fiber laser can maintain the mode locking at the pumping power of 160 mW to stably generate periodic optical pulses with width less than 170 fs and timing jitter lower than 75 fs in the 1.55 µm wavelength region, when the fundamental repetition rate of the laser is continuously tuned between 49.65 and 50.47 MHz. Moreover, this fiber laser has a feature of turn-key operation with high repeatability of its fundamental repetition rate in practice. [ABSTRACT FROM AUTHOR]

In this review we discuss the progress of the past decade in testing for a possible temporal variation of the fine structure constant α. Advances in atomic sample preparation, laser spectroscopy and optical frequency measurements led to rapid reduction of measurement uncertainties. Eventually laboratory tests became the most sensitive tool to detect a possible variation of α at the present epoch. We explain the methods and technologies that helped to make this possible. [ABSTRACT FROM AUTHOR]

The trapping and laser cooling of 40Ca+ ion on the way toward optical frequency standards have been developed. A single 40Ca+ ion is trapped in the miniature Paul trap and laser cooled by two frequency-stabilized diode lasers. A commercial Ti:Sapphire laser system at 729 nm is referenced to a high-finesse cavity to meet the requirements of ultra narrow linewidth of the 4s2S1/2-3d2D5/2 electric quadrupole transition. Its center frequency is preliminarily measured to be 411 042 129 686.1 (2.6) kHz. The attempt to finally lock the 729-nm laser system to atomic transition is made. Further work to improve the accuracy of measurement and the stabilization of system locking is in consideration and preparation. [ABSTRACT FROM AUTHOR]

The authors present a compact high-performance laser-pumped Rubidium atomic frequency standard exploiting the advantages of laser optical pumping for improved stability. The clock is based on an industrial Rb clock with the lamp assembly removed and optically pumped by light from a compact frequency-stabilized laser head. The modification of the buffer gas filling in the clock resonance cell reduces instabilities on medium-term timescales arising from the ac Stark effect and temperature variations. The frequency stability of the demonstrator clock was measured to be better than 4 × 10-1203C4-⅛up to 104 s, limited by the local oscillator (LO) quartz and RF loop electronics. Long-term drifts under atmosphere amount to 2-6 × 10-3/day only, comparable to or lower than that for lamp-pumped clocks under similar conditions. Typical signal contrasts lie at around 20%, corresponding to a shot-noise limit for the short-term stability of 2 × 10-1303C4-⅛. The results clearly demonstrate the feasibility of a laser-pumped Rb clock reaching < 1 × 10-1203C4-⅛ in a compact device (< 2 L, 2 kg, 20 W), given the optimization of the implemented techniques. Compact high-performance clocks of this kind are of high interest for space applications such as telecommunications, science missions, and future generations of satellite navigation systems [GPS, global orbiting navigation satellite system (GLONASS), European satellite navigation system (GALILEO)]. [ABSTRACT FROM AUTHOR]

The potential of optical fiber ring resonators for radio frequency (RF) or microwave signals filtering on optical carriers is demonstrated on a short length high Q resonator. The problem of the frequency shift due to the resonator self heating with the optical power is solved thanks to a Pound-Drever feedback loop. A multifrequency RF filter is obtained, with a frequency step of 205 MHz between resonances, and a 3-dB bandwidth of 2.4 MHz. This corresponds to the computed optical resonator 3-dB bandwidth, and thus represents an efficient technique for the measurement of ultrahigh Q optical resonators. In the field of microwave applications, the equivalent Q -factor obtained is particularly interesting in the upper microwave range. [ABSTRACT FROM PUBLISHER]

We realized the repetition rate multiplication in a phase-modulated soliton fiber laser with the rational harmonic mode-locking method. A modified pulse phase-locking method is used to stabilize the fiber laser at 10-GHz repetition rate with the rational harmonic order up to five (limited by the component performance). The laser showed an excellent stabilization performance in a long-term bit-error-rate test [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

In this paper, the carrier‐envelope‐offset (CEO) frequency stabilization of a Kerr‐lens mode‐locked femtosecond oscillator with average power 105 W is presented. Intra‐cavity Kerr lensing is realized in a quartz crystal that simultaneously serves as an acousto‐optic loss modulator. This novel method results in a CEO frequency stable laser with high average power and a residual in‐loop phase noise below 90 mrad. Furthermore, an all‐solid‐state bulk broadening stage is presented. The compressed, CEO frequency‐stabilized output has a peak power exceeding 67 MW at a pulse duration of 40 fs and a repetition rate of 15.6 MHz. The intra‐cavity peak power of the CEO frequency‐stabilized oscillator is around 200 MW. These results pave the way toward compact, transportable all‐solid‐state drivers with high repetition rates for deep UV and XUV frequency combs and other nonlinear processes. Carrier‐envelope‐offset (CEO) frequency stabilization of a Kerr‐lens mode‐locked thin‐disk oscillator by realizing Kerr‐lensing in a quartz crystal that simultaneously serves as an acousto‐optic loss‐modulator is presented. The novel method results in a high peak power CEO‐frequency stable laser, paving the way toward compact all‐solid‐state drivers with high repetition rates for deep UV and XUV frequency combs and other nonlinear processes. [ABSTRACT FROM AUTHOR]

The power of a HF laser versus cavity frequency is measured in the presence of saturable HF gas. A resonant power maximum is observed which is relevant to laser frequency stabilization and molecular line broadening measurement. [ABSTRACT FROM AUTHOR]