Abstract

Tunable diode lasers utilizing an external cavity laser (ECL) design can provide many attractive features needed for WDM application such as a very narrow linewidth, wide continuous tuning range, high output power and considerable inventory reduction.¹ The use of tilted or angle waveguide gain chips²⁻⁴ for ECL fabrication eliminates the need for very accurate thickness and refractive index material deposition on one or more of the emitting facets. The elimination of this very low-reflective coating (R < 10⁻⁴) deposition procedure makes possible mass production of low-cost gain chips. Our modeling shows that tilted waveguide chips even with an as-deaved facet can have effective reflective coefficient as low as 6×10⁻⁴if waveguide axis is tilted only by 6° relative to chip facet (Fig. 1(a)). Effective reflective coefficient in Fig. 1(a) was estimated as an overlap of the ridge waveguide mode with the mode reflected from the tilted chip facet. The ridge mode near-field used for this calculation was derived in Gauss approximation from experimental data on the chip far field.

© 2002 Optical Society of America