Development of Polarization Diversity Sampling Head Unit using Organic AANP Crystals and 160 Gb/s Far-end Waveform Measurement

Abstract

It was reported that 2-adamantylamino-5-nitropyridine (AANP ) crystal, which is a new developed organic crystal, could be applied to the high sensitive optical sampling head over C-band (1530 to 1565 nm). But the precious characteristics of the AANP was not well known.So we studied the precious characteristics of AANP crystal and the expanding thechnology for wavelength range of the optical sampling head unit using this crystal. Futhermore we developed the assembling technique of a polarization diversity sampling head unit for polarization indpendent mesuring waveforms based on this studies.This paper reports the cheracteristics of an AANP crystal for OSO, a developed configuration of a polarization diversity sampling head unit. we will demonstrate 160 Gb/s far-end measurement using a polarization-independent optical sampling head unit.We evaluated the relationship between the normalized conversion efficiency and polarization state for incident light. The result confirms that the conversion efficiency range of the AANP crystal can be expanded by setting the optimimum polarization. Then we evaluated the conversion efficiency for three different incident angles of +1°, 0°, -1° around an incident angle of 90°. The result confirms that the wavelength with peak efficiency can be adjusted to the C-L bands using the AANP surface incident light angle, because the peak efficiency shifted to the long wavelength range at a -1° incident angle, and to the short wavelength range at a +1° incident angle.These results show that we can build a high-sensitivity optical sampling head unit covering the C-L bands using the above assembly technique and an AANP crystal. Figure 1 shows the characteristics of the AANP conversion efficiency of the prototype polarization diversity sampling head unit and the KTP conversion efficiency of a traditional polarization dependent sampling head unit. The SFG conversion efficiency of the AANP in the developed polarization diversity head unit is 20 times higher than the traditional sampling head using KTP over the C-L bands, and the 3 dB wavelength bandwidth is two times wider. Figure 2 shows the result of far-end measurement of a 160 Gb/s waveform after 5 km transmission using this head. It confirms that the OSO with prototype polarization diversity head can measure post-transmission signal waveforms stably in spite of changing polarization state in an optical transmission fiber frequently. Because an eye diagram waveform for RZ signal is opened clearly. We have previously developed a turn-key-ready OSO (optical sampling oscilloscope) system with a jitter of 0.2 ps rms and a resolution of 1 ps. Recently, we studied the characteristics of an AANP (2-adamantylamino-5-nitropyridine) crystal, which is the newest organic crystal for achieving a high-sensitivity optical sampling head unit for the OSO system. We developed a polarization-independent sampling head with a high sum-frequency conversion efficiency over the C-L bands using the AANP crystals.This paper reports the characteristics of the AANP cry...

Consideration of direct bit‐rate measuring method based on extracting envelope signal

“…The waveform measurement system includes (1) a sampling clock generator, (2) an optical sampling pulse generator that generates the sampling light (pulse width about 500 fs, repetition frequency about 10 MHz) synchronously to the clock of the sampling clock generator, (3) a polarization-diversity optical sampling head [6] that generates the cross-correlation signal between (6) (7) (8) Fig. 3.…”