Tapered amplifier laser with frequency-shifted feedback

In the last paragraph of Sec. 1, we changed "we demonstrate for the first time an FSF laser that" to "we demonstrate an FSF laser that" and added "In mutually independent work, a similar system was developed for broadband laser cooling, as indicated by conference abstract [19].".

At the end of Sec. 2.3 we added "The comb can be stabilized in frequency by locking the seed laser to a desired frequency, e.g. a Rb spectroscopy line. In previous work such stabilization required an additional lock of a comb line to a reference laser, see [13, 22] and references therein."

In Sec. 4 we added "In contrast to other frequency combs [23, 8] our comb has a narrower spectrum. It covers 0.7 nm, which is a fraction of the 3dB gain bandwidth of our TA (11 nm). We observe that the spectrum can be broadened by increasing the AOM frequency, although less than proportional to that frequency. Broadening the comb width would be valuable to increase the range of application of our scheme and could be a topic for further research. Still, a comb spanning hundreds of GHz is relevant to many applications and we plan to use the frequency comb of our FSF laser as frequency reference for photoassociation spectroscopy of RbSr molecules [24]."

"a linewidth below 1MHz."->"a linewidth below 1MHz on a timescale of 5us."

- P3 344.25 => 384.25THz

- P3 replaced groves with grooves

- P5 "by orders of magnitude" => "by four orders of magnitude"
done

- P7 "For comparison we also show the spectrum obtained by the grating spectrometer as blue curve in Fig. 4."->"For comparison we also show the spectrum obtained by the grating spectrometer in Fig. 4 (solid blue)."

- Fig 5: We now integrated the signals over frequency. The vertical label is changed to "Relative peak power " and in the caption we added "The relative peak power is obtained by integrating peaks such as the ones shown in Fig. 3a2 and 3b2 over frequency and comparing them to the noise floor.".

P4: "The full width half maximum of the spectrum is 120 GHz."->"The full width half maximum of the spectrum is 120 GHz independent of the center frequency. The spectrum can be broadened by increasing the AOM frequency, as shown in Sec. 3.2."

P6: "The power of the seed laser at the TA input
facet was 80uW."

"The FSF laser exhibits
coherent modeless broadband radiation"->"The FSF laser emits
coherent modeless broadband radiation"

"A. Bayerle1*, S. Tzanova2,3, P. Vlaar1 B. Pasquiou1 F. Schreck1,y"->"A. Bayerle1*, S. Tzanova2,3, P. Vlaar1, B. Pasquiou1, and F. Schreck1,y"

P5: "an arm length difference of 26.0(4) cm."->"an arm length difference of 26.00(4) cm."

P5: "Each sub-system
will be now described in detail."->"Each sub-system
will now be described in detail."

P3: "used to resolve the mode structure of the FSF laser, is
shown in Fig. 1c."->"used to resolve the mode structure of the FSF laser, is shown in the lower part of Fig. 1c."

P6: "contains additional sharp lines at integer multiples
of f_{AOM}."->"contains additional sharp lines at integer multiples
of fAOM. contains additional sharp lines at integer multiples
of f_{/rm AOM}."

P7: "is present in the spectrum for all
seed intensities presented here."->"is present in the spectrum for all
seed intensities explored here."

P5: "Fig. 3a and 3b"->"Fig. 3a2 and 3b2"

P8: "Fig. 6" -> "Fig. 5"