High-resolution radio frequency spectral analysis with photon echo chirp transform in an Er:YSO crystal

Photon echo chirp transform using a stabilized frequency agile laser

“…More generally, when the readout field is modulated by a signal sðtÞ, the detection of the total PE signal directly yields the power spectrum of the modulation signal jsðf Þj 2 . This spectrum is displayed in the time domain with a linear time-to-frequency relation f ¼ r:t. Depending on the minimum delay set between the engraving chirps, one can display a double or a single sided spectrum [7]. This excitation scheme corresponds to a CTA [10].…”

“…On the one hand, such crystals exhibit potential bandwidths up to 270 GHz and resolutions down to 70 Hz [2] when cooled down to a few kelvin. On the other hand, PEs give access to a wide range of coherent linear filtering operations [3][4][5][6][7]. Frequency agile lasers, i.e., capable to ramp fast over the crystal bandwidth with an excellent precision, are the enabling tools.…”

“…The scientific community promoting PE processing is developing dedicated devices and systems such as Doppler correlators [4], true-time delay lines [5], and RF signals spectral analyzers [6][7][8][9]. Nowadays, the more advanced PE demonstrators have surpassed conventional technologies (electronics, acousto-optics) in terms of analog bandwidth [4,6,8,9].…”

“…We recently proposed [10] and demonstrated [7] a spectral analyzer architecture based on the chirp transform algorithm (CTA). The experimental results were limited to a narrow bandwidth of 20 MHz because of the lack of a frequency agile laser source.…”

Experimental observation of spectral diffusion in an optically pumped crystal

“…During the last decades, optical coherent transients have been extensively studied for wideband signal processing, including radiofrequency-signal spectral analysis [1,2] correlation [3] and range-Doppler processing [4]. Although most experiments have been performed in Tm:YAG at 793 nm, Er-doped materials are of great interest in order to take advantage of off-the-shelf, low cost and high performance optical components developed at the telecommunication wavelength.…”