Ultra-narrow linewidth full C-band tunable single-frequency linear-polarization fiber laser

Abstract

An ultra-narrow linewidth full C-band tunable single-frequency linear-polarization fiber laser based on self-injection locking has been demonstrated. By the use of a tunable narrow-band fiber Fabry-Perot interferometer, the laser wavelength could be flexibly tuned from 1527 to 1563 nm with linewidths of < 700 Hz. The laser frequency noise is less than 40 dB re Hz/Hz^1/2 at low frequencies (< 100 Hz) and reaches -5 dB re Hz/Hz^1/2 at around 25 kHz. The measured relative intensity noise (RIN) is less than -130 dB/Hz with regard to frequencies of over 3 MHz, while the obtained linear polarization extinction ratio (LPER) is higher than 28 dB. This ultra-narrow linewidth low-noise tunable single-frequency linear-polarization fiber laser provides a promising candidate for high-order quadrature amplitude modulation (QAM) optical communication system.

Acousto-Optic–Based Wavelength-Comb-Swept Laser for Extended Displacement Measurements

“…Because the proposed WCSL, which is based on an AOTF, has no mechanical moving parts for the selection of the wavelength and is solely driven by an electro-optic signal, it has some advantages in comparison to other types of WCSLs using an FFP-TF, such as high environmental stability, wavenumber linearity, and adaptability to various types of driving functions [5,6,7,8]. Figure 5 shows the linear relationships between the applied RF signal and the output wavenumber [14] for both WSL and WCSL, which have a high wavenumber linearity of R 2 = 0.9999.…”

“…Recently, optical-domain sub-sampled OCT has been proposed to measure larger depth ranges and reduce the data acquisition bandwidth simultaneously [4,5,6,7,8,9,10]. There has been a limitation in reducing the linewidth in the conventional continuous-spectrum broadband light source of spectral-domain optical coherence tomography (SD-OCT) and the continuous wavelength-swept laser source of SS-OCT.…”

“…There has been a limitation in reducing the linewidth in the conventional continuous-spectrum broadband light source of spectral-domain optical coherence tomography (SD-OCT) and the continuous wavelength-swept laser source of SS-OCT. Therefore, a spectrally sampled broadband light source for SD-OCT and a wavelength-comb-swept laser (WCSL) source for SS-OCT can be used to reduce optical interference fringe decay and extend the interferometric displacement measurement range because of their discretely distributed comb-like spectral information with fixed k -space periodicity [4,5,6,7,8,9,10]. …”

“…Most WCSLs use two intra-cavity filters, a tunable wavelength-selection filter (TWSF) and a Fabry-Pérot etalon filter [5,6,7,8,9,10]. The TWSF is employed for the tunable selection of the output wavelength along repeated time and the etalon filter for the narrowing of the spectral linewidth at each wavelength with fixed k -space periodicity.…”

“…The TWSF is employed for the tunable selection of the output wavelength along repeated time and the etalon filter for the narrowing of the spectral linewidth at each wavelength with fixed k -space periodicity. In general, the wavelength sweeping of WCSL can be simply achieved by mechanical moving components, such as a fiber Fabry-Pérot tunable filter (FFP-TF) [5,6,7] and a polygon mirror scanner [8]. These mechanically sweeping parts are known to suffer from the disadvantages of non-linear tuning of the wavenumber and environmental instability.…”