Phase-predictable tuning of single-frequency optical synthesizers

Rohde, Felix; Benkler, E.; Puppe, Thomas; Unterreitmayer, Reinhard; Zach, Armin; Telle, H.R.

doi:10.1364/ol.39.004080

Cited by 15 publications

(13 citation statements)

References 11 publications

(19 reference statements)

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“…(a) A continuously-tunable laser (CTL) is phase-locked to a self-referenced Er:fiber comb whose frequency is repeatedly shifted over a given range by phase modulation (see Ref. 34 for technical details). A trigger signal marks the instants when the laser hits a grid of frequencies that is predefined within the swept range, with a mesh size down to f rep /64 in our case.…”

Section: Spectroscopic Resultsmentioning

confidence: 99%

“…In this work we are overcoming these issues by applying the endless frequency concept of OFC lines proposed by Benkler et al 33 , which enables coherence transfer together with removal of any ambiguity problem by a continuous shifting of the comb lines themselves, while the cw laser follows the shift thanks to a phase lock with a fixed offset to the same comb mode. The proof of principle of the shifter and the characterization of two identical systems were performed a few years ago with the demonstration of mutual coherence of two lasers independently locked to a comb shifting over 28 GHz 34 . Here we propose a substantial leap forward, with an integrated system that offers 100 times larger spectral coverage and 30 times faster tuning speed.…”

Section: Schematic Illustration and Technical Implementationmentioning

confidence: 99%

“…This ensures an endless frequency shifting of the comb and in turn of the cw laser that is locked to one of the comb lines. Phase and frequency deviation of the cw laser has been investigated in detail in Rohde et al 34 . In particular it has been shown to be insensitive to variations of the 2π voltage by a few percent.…”

Section: Schematic Illustration and Technical Implementationmentioning

confidence: 99%

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Comb-locked frequency-swept synthesizer for high precision broadband spectroscopy

Gotti

Puppe

Mayzlin

et al. 2020

Sci Rep

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frequency combs have made optical metrology accessible to hundreds of laboratories worldwide and they have set new benchmarks in multi-species trace gas sensing for environmental, industrial and medical applications. However, current comb spectrometers privilege either frequency precision and sensitivity through interposition of a cw probe laser with limited tuning range, or spectral coverage and measurement time using the comb itself as an ultra-broadband probe. We overcome this restriction by introducing a comb-locked frequency-swept optical synthesizer that allows a continuous-wave laser to be swept in seconds over spectral ranges of several terahertz while remaining phase locked to an underlying frequency comb. This offers a unique degree of versatility, as the synthesizer can be either repeatedly scanned over a single absorption line to achieve ultimate precision and sensitivity, or swept in seconds over an entire rovibrational band to capture multiple species. the spectrometer enables us to determine line center frequencies with an absolute uncertainty of 30 kHz and at the same time to collect absorption spectra over more than 3 THz with state-of-the-art sensitivity of a few 10 −10 cm −1. Beyond precision broadband spectroscopy, the proposed synthesizer is an extremely promising tool to force a breakthrough in terahertz metrology and coherent laser ranging.

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Section: Spectroscopic Resultsmentioning

confidence: 99%

Section: Schematic Illustration and Technical Implementationmentioning

confidence: 99%

Section: Schematic Illustration and Technical Implementationmentioning

confidence: 99%

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Comb-locked frequency-swept synthesizer for high precision broadband spectroscopy

Gotti

Puppe

Mayzlin

et al. 2020

Sci Rep

Self Cite

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“…Use of an external frequency tuning apparatus, such as an electro-optic modulator (EOM), provides a potential cure to this problem. Although the typical tuning range attained by an EOM is limited to a few hundred MHz or less [78], scanning ranges of tens of GHz are potentially possible with modern EOMs or with an innovative new method called "endless frequency scanning", which is not limited by the tuning range of the EOM [220,221].…”

Section: Mid-infrared Frequency-comb Spectroscopymentioning

confidence: 99%

Mid-infrared optical parametric oscillators and frequency combs for molecular spectroscopy

Vainio

Halonen

2016

Phys. Chem. Chem. Phys.

124

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Nonlinear optical frequency conversion is one of the most versatile methods to generate wavelength-tunable laser light in the mid-infrared region. This spectral region is particularly important for trace gas detection and other applications of molecular spectroscopy, because it accommodates the fundamental vibrational bands of several interesting molecules. In this article, we review the progress of the most significant nonlinear optics instruments for widely tunable, high-resolution mid-infrared spectroscopy: continuous-wave optical parametric oscillators and difference frequency generators. We extend our discussion to mid-infrared optical frequency combs, which are becoming increasingly important spectroscopic tools, owing to their capability of highly sensitive and selective parallel detection of several molecular species. To illustrate the potential and limitations of mid-infrared sources based on nonlinear optics, we also review typical uses of these instruments in both applied and fundamental spectroscopy.

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“…In both situations, special techniques that allow jumping over the "dead zones" are required [17][18][19]. Continuous frequency shifting has been demonstrated in [20,21] where a part of the comb light is split off and is then sent into an electro-optic modulator used to shift the carrier frequency (f CEO ) of the OFC by changing the optical phase of the light during the time between subsequent pulses of the mode-locked laser generating the comb. Possibly the easiest to implement methods belonging to this class rely on the change of the locked laser's frequency using an acousto-optic modulator (AOM) either before or after it is compared by optical heterodyne to the OFC [22].…”

mentioning

confidence: 99%

Method for independent and continuous tuning of N lasers phase-locked to the same frequency comb

2015

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We present a method of phase-locking any number of continuous-wave lasers to an optical frequency comb (OFC) that enables independent frequency positioning and control of each laser while still maintaining lock to the OFC. The scheme employs an acousto-optic modulator (AOM) in a double pass configuration added to each laser before its light is compared by optical heterodyne with the comb. The only requirement is that the tuning bandwidth of the double pass AOM setup be larger than half the OFC repetition rate. We demonstrate this scheme and achieve an arbitrary frequency tuning precision, a tuning rate of 200 MHz/s and a readout precision at the 1 kHz level.Modern experiments often require multiple lasers, differing in frequencies by tens of THz and referenced to atomic transitions or stable cavities. For example, optical clocks based on 88 Sr + utilize stabilized coherent sources at 422 nm, 674 nm, 1033 nm and 1092 nm [1,2]. For applications in spectroscopy and related experiments aiming at production of ultracold ground state molecules [3][4][5][6][7], an additional technical difficulty arises from the need to vary the frequency of these stabilized lasers over hundreds to thousands of MHz to characterize a priori unknown molecular levels.Since the development of the self-referenced optical frequency combs (OFC) [8,9] it has been possible to frequency stabilize lasers to the resulting "frequency ruler" by stabilizing the heterodyne beatnote between the laser and the OFC. Using the broadened spectrum of the OFC provides a wide bandwidth for locking, typically corresponding to the 500 -1100 nm range for titanium sapphire based systems [8]. Moreover, non-linear optical processes (including frequency doubling the OFC output when the CW frequency is higher or frequency mixing the OFC output with the CW source itself when the CW frequency is lower) can be used to reliably lock the CW laser even when its frequency has no overlap with the OFC's output spectrum [10,11]. It is worth noting that coherent sources at wavelengths below 500 nm are often based on frequency doubling [13] or frequency sum generation [14], and therefore their stabilization can be done by referencing the seed lasers before nonlinear mixing.The frequency f L of a laser frequency locked to an OFC by stabilizing the beatnote produced in an optical heterodyne with the OFC can be expressed as f L = f CEO + n × f rep ± f beat , where f CEO is the carrier envelope frequency, f rep is the repetition rate of the comb and ±f beat refers to the heterodyne beatnote between the laser frequency and the comb tooth to which the laser is locked.The most straightforward method to simultaneously achieve absolute frequency stability and wide tunability of a CW laser referenced to an OFC relies on the change of f rep [11,15,16], which is multiplied by the mode number n (on the order of 10 6 ) of the comb element to which the laser is referenced. This allows for scanning ranges of many GHz, typically limited by the mode-hop-free tuning range of a laser. This method, ho...

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Phase-predictable tuning of single-frequency optical synthesizers

Cited by 15 publications

References 11 publications

Comb-locked frequency-swept synthesizer for high precision broadband spectroscopy

Comb-locked frequency-swept synthesizer for high precision broadband spectroscopy

Mid-infrared optical parametric oscillators and frequency combs for molecular spectroscopy

Method for independent and continuous tuning of N lasers phase-locked to the same frequency comb

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