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Wide-bandwidth mode-hop-free tuning of extended-cavity GaN diode lasers

Hult J, Burns IS, Kaminski CF (2005) "Wide bandwidth mode-hop free tuning of extended cavity GaN diode lasers" Applied Optics 44:3675-3685, DOI:10.1364/AO.44.003675, | pdf


We present a new approach for extended-cavity diode-laser tuning to achieve wide mode-hop-free tuning ranges. By using a multiple piezoactuated grating mount, the cavity length and grating angle in the laser can be adjusted independently, allowing mode-hop-free tuning without the need for a mechanically optimized pivot-point mount. Furthermore, synchronized diode injection-current tuning allows diode lasers without antireflection coatings to be employed. In combination these two techniques make the construction of a cheap, efficient, and easily optimized extended-cavity diode laser possible. A theoretical analysis is presented for optimal control of piezoactuator displacements and injection current to achieve the widest possible mode-hop-free tuning ranges, and a comparison is made with measurements. The scheme is demonstrated for blue and violet GaN lasers operating at ∼450 nm and ∼410 nm, for which continuous tuning ranges exceeding 90 GHz have been achieved. Examples of applications of these lasers are also given.