We have found a non-destructive method of using simple optical metrology for precisely estimating the grating height of distributed-feedback laser diodes (DFB-LDs). An InGaAsP/InP grating with a period of 0.2 pin and height from 15 to 45 nm was grown using metal-organic vapor-phase epitaxy (MOVPE), it was successfully evaluated using un-polarized simple optical metrology. Spectroscopic scatterometry, an optical-wavelength light-diffraction technique is emerging as a fast, accurate and non-destructive grating height monitor. A precise grating profile evaluation technique with nanometer scale accuracy enables obtaining an accurate coupling coefficient (kappa L) for DFB-LDs. DFB-LDs with well-controlled kappa L show grate promise of high-performance and high-yield characteristics. (c) 2006 Elsevier B.V. All rights reserved.