CORRIGENDUM: Parametric spectro-temporal analyzer (PASTA) for real-time optical spectrum observation.

The authors neglected to cite some of the previous studies related to Fourier Transformation in the Introduction section of this Article1234. These additional references are listed below as references 1,2,3,4, and should appear in the text as below.

“This concept was first introduced by Azana et al. for real-time Fourier transformation9, where group-velocity dispersion (GVD) directly stretched spectra in the time domain. After wavelength-to-time mapping, the spectrum can be captured by a single-pixel detector and a real-time oscilloscope.”

should read

“Earlier work on real-time Fourier transformation has been demonstrated by Tong1, Bhushan2 and Azana9 where group-velocity dispersion (GVD) directly stretched spectra in the time domain. After wavelength-to-time mapping, the spectrum can be captured by a single-pixel detector and a real-time oscilloscope. Its first demonstration in applying DFT spectroscopy3 was not as practical until the introduction of optical amplification as in ADFT4.”

In addition Table 1 is incomplete and should also include an additional reference5 listed as reference 5 below. Table 1 should read:

Table 1

Performance of PASTA versus different technologies

Specifications	OSA24 AQ6370C (Yokogawa)	FROG25 FROG Scan (MesaPhotonics)	BOSA26 (Aragon Photonics)	ADFT7	PASTA
Resolution	0.02 nm	0.2 nm	80 fm	~0.04 nm	0.03 nm
Wavelength range	100 nm	100–600 nm	37 nm	10 nm(5)	5 nm
Sensitivity	−60 dBm(1)	>30 dBm(3)	−70 dBm	>30 dBm (3)	−30 dBm(4)
Frame rate	5 Hz (1)	2 Hz	1 Hz	25 MHz	100 MHz
Input condition	Any	Short pulse (fs~ps)	Any	Short pulse (fs~ps)	Any
Observation time span	Any	30 ps	Any	~20 ms	~20 ms
Polarization	Any	Sensitive	Sensitive	Any	Sensitive(2)

(1) There is a trade-off between sensitivity and frame rate of the OSA, e. g. when sensitivity = –90 dBm, frame rate = 1/(75 sec) = 13.33 mHz. (2) It can be solved by polarization-diversity technique23. (3) Since the FROG and the ADFT systems primarily measure the short pulse, here the sensitivity refers to the peak power of the pulse. (4) PASTA sensitivity is characterized with the CW source, and there is no sensitivity improvement for the pulse source measurement, when comparing with the ADFT. (5) Here the wavelength range is only for this specified application, the DFT process can be operated over much wider wavelength range, e.g. over 100 nm5.