Fiber grating feedback device for external-cavity semiconductor

Abstract

The invention discloses a fiber grating feedback device for an external-cavity semiconductor, comprising a fiber grating packaging die, a polarization maintaining fiber grating and a protection sleeve; the inner part of the fiber grating packaging die is provided with a through V-shaped groove in the length direction of the fiber grating packaging die, the polarization maintaining fiber grating ispackaged on a V-shaped groove of the fiber grating packaging die, a fiber lens is arranged at the front end of the polarization maintaining fiber grating, and a tail fiber coated with a coating layeris arranged at the tail end of the polarization maintaining fiber grating; the fiber grating packaging die is fixed inside the protection sleeve, the end face of the protection sleeve is fixed with the end face of the fiber grating packaging die, and the side face of the fiber grating packaging die is fixed with the protection sleeve. According to the fiber grating feedback device in the invention, the grating region of the fiber grating is adhered to the V-shaped groove of the fiber grating packaging die for integrated packaging, the V-shaped groove provides symmetric support for the polarization maintaining fiber grating, so that the stress caused by silica gel in the bonding process can be effectively reduced, and the reflection spectrum characteristic and the polarization characteristic of the fiber grating are kept unchanged.

Description

technical field [0001] The invention belongs to the technical field of optical fiber gratings, and in particular relates to an optical fiber grating feedback device for external cavity semiconductors. Background technique [0002] The phase frequency noise of external cavity semiconductor laser can be suppressed by external cavity feedback technology to obtain narrow linewidth laser output, and it has obvious advantages in wavelength range, luminous efficiency, reliability, stability and cost, and integrated design It can make it have a more compact and stable cavity structure and extremely low intensity noise, so it has a wide range of high-precision laser applications such as fiber optic sensing, space coherent laser communication, gravitational wave detection, high-precision time-frequency transmission, and synthetic aperture radar. application prospects. At present, the commonly used feedback devices for external cavity semiconductor lasers mainly include silicon-based ...

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Problems solved by technology

However, the early literature reports of this type of laser used Bragg gratings written in single-mode fiber as the feedback element, and the line width generally stayed at the level of tens to hundreds of kilohertz. The narrow linewidth laser output of <10 kHz has been realized on the basis of the laser output, but its polarization characteristics cannot be guaranteed [Pan Biwei, Yu Liqiang, Lu Dan, Li Linsen, Zhang Limeng, Li Zhaosong, Su Hui, Zhao Lingjuan. 20 kHz narrow linewidth Fiber Bragg Grating External Cavity Semiconductor Laser[J]. China Laser, 2015, 42(5): 502007.]; In addition, the University of Southampton in the UK wrote Bragg gratings on a new type of large numerical aperture photosensitive fiber, and the flame hydrolysis deposition process It is integrated on a silicon-based flat substrate for integrated packaging, which greatly improves the stability of the fiber grating, and uses this as a feedback element to achieve a 14 kHz narrow linewidth laser output, which is realized after butt coupling with a polarization-maintaining single-mode fiber Polarization-maintaining laser output, two different types of fiber in [Stephen G. Lynch, Christopher Holmes, Sam A. Berry, James C.Gates, Alexander Jantzen, Teresa I. Ferreiro, Peter G. R. Smith. Externalcavity diode laser based upon an FBG in an integrated optical fiber platform[J]. Optics Express, 2016, 24(8): 8391-8398.】

It can be seen that the existing schemes cannot meet the application requirements in realizing single-linear polarization of lasers

[0004] Using the polarization-maintaining fiber grating written on the polarization-maintaining fiber as the feedback element, the fast axis or the slow axis of the polarization-maintaining fiber is aligned with the polarization direction of the output light of the semiconductor gain chip after rotating, which can provide effective optical feedback and flexible wavelength selection. High-quality polarization-maintaining laser output can be obtained at the same time, but the polarization-maintaining fiber grating is very fragile, and the stress generated by fiber bending, displacement, temperature change, etc. will cause the degradation of the spectral characteristics and polarization-maintaining properties of the grating, affecting the output laser. performance

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