SBIR-STTR Award

Eotron’s advanced diode laser packaging technology allows construction of an efficient and compact line-narrowed diode stack combined with Volume Brag Grading (VBG) for pumping a Diode Pumped Alkali Laser (DPAL). A single laser diode bar with a 20pm spectral line-width demonstrated more than 30W of cw output power at 780nm pumping a rubidium vapor laser. However, current diode laser stacks have failed to narrow spectral line-widths below 0.05nm due to pointing inaccuracies with the individual diode bars and thermal instability of a large VBG. Eotron’s technology places all laser diode bars in near perfect alignment to the VBG, narrowing spectral line-width. Lowering thermal resistance of the silicon diode package improves electrical-to-optical efficiency, stabilizes turn-on time and wavelength drift of the DPAL system. Also, the cooling technology of Eotron’s Silicon Macro-Channel (SMC) design will be applied to the VBG element to stabilize wavelength drift and local thermal effect. Eotron’s SMC and silicon packaging implemented in diode laser stacking along with VBG cooling, will demonstrate improved performance and spectral line-width narrowing due to its’ accurate micron-level assembly of the diode stack, overcoming the limitations of current diode laser technologies to allow the delivery of a cost effective pumping module for DPAL systems.

Keywords:
diode laser, laser diode bar, narrow band, DPAL, DPSS, Line-Narrowed, external cavity, 780 nm

Advanced laser diode technology developed using silicon MEMS packaging enables the construction of an efficient and compact line-narrowed diode stack combined with a Volume Brag Grading (VBG) to create a Diode Pumped Alkali Laser (DPAL). A single laser diode bar, with 20pm spectral line-width, has demonstrated more than 30W of CW output power at 780nm pumping a rubidium vapor laser. However, current methods used to assemble laser diode stacks prevent narrowing the spectral line-width below 0.05 nm due to pointing inaccuracy of the individual laser diode bars and thermal stability issues with a large VBG. A new 3D silicon based laser diode technology enables all laser diode bars to be packaged in near perfect alignment to the VBG for narrowing down spectral line-width. In addition, the lower thermal resistance of the silicon laser diode package improves electrical-to-optical efficiency and stabilizes both turn-on time of the DPAL system and wavelength drift. The Silicon Macro-Channel (SMC) cooling technology will also be applied to the VBG element to stabilize wavelength drift and minimize any thermal gradient in order to maintain narrow line-width. The SMC and silicon MEMS packaging implemented in the new laser diode technology and VBG cooling has demonstrated improved laser diode performance and spectral line-width narrowing due to the accurate micron-level assembly of the laser diode bar. This technology will overcome the limitations of current diode approaches and prove the feasibly of a high performance and cost-effective pumping source for DPAL systems. Approved for Public Release 14-MDA-7739 (18 March 14).

Keywords:
Laser Diode Arrays (LDA), Line-Narrowed, Volume Bragg Grating (VGB), Diode Pumped Alkali Laser (DPAL), 780nm