<title>Fiber grating stabilized WDM laser source with hermetically sealed package</title>

Abstract

Fiber grating stabilized single-mode diode laser is developed in a highly reliable hermetically sealed package for dense WDM applications. It provides a very stable laser output with an output power stability of dB over 12 hours. Output wavelength accuracy of the laser is precisely controlled by a fiber grating with a fabrication tolerance of 1 nm. The laser has a lmewidth of 50 kHz, an output power larger than 6 mW and a 2.2 nm quasi-continuous tuning.Multi-Gb/s lightwave systems and dense WDM networks require a narrow linewidth laser source with precise wavelength selectivity, constant power output and excellent wavelength stability. However, the widely used DFB diode lasers have wavelength selection difficulties. A fiber Bragg grating stabilized laser source with a linewidth of 50KHz and 2.2nm wavelength tunability in a hermetically sealed package is reported in this paper. The stabilized single-mode laser also has a 45dB side lobe suppression. Figure 1. Schematic structure of fiber grating laser . . AR: Antireflection coatingThe schematic structure of dense WDM laser source is shown in Figure 1. A laser chip is mounted in the center ofthe hermetically sealed package. One facet of the laser chip is AR-coated with a reflectivity of less than 0.1%. The lasing emission output from the AR-coated facet is coupled into a fiber Bragg grating of high reflectivity. The output from the cleaved facet is collimated by a miniature lens set followed by an optical isolator into a single-mode fiber. The lasing wavelength is determined by the peak reflection of the fiber grating. The high reflection fiber grating is fabricated by an excimer laser using side-writing phase mask technique. The grating has a larger than 90% reflectivity and a less than 0.4 nm of 3 dB bandwidth.The peak wavelength of the fiber grating is controlled by a high reproducible fabrication technique with an accuracy of 0. mm. The built-in isolator ensures a stable laser output with immunity to back reflection. All parts of the laser are precisely welded in a hermetically _____________________________ sealed butterfly package by multi-beam Nd:YAG laser system. O-8194-2294-O/96/$6.OO SPIE Vol. 2893 /573 Laser output__________ isolator LD chip10 0 ---t 1--4--i -20 -30 --!WWvWvJVVWVWWwvwv 1540 1545 1550 1555 Wavelength (nm) Figure 2 A typical output spectrum with sidelobe suppresion >45 dB Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/25/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx