Optimization of multiple exposure gratings for widely tunable lasers

Abstract

Abstract-A theoretical study of the reflection spectra of multiple holographic exposure distributed Bragg reflector gratings is presented. We will show that such a grating can exhibit a uniform reflection comb if the relative phases of the superimposed gratings are well chosen. The tolerances on the optimal phases are of the order of 0.09 radians for six superimposed gratings to 0.04 radians for ten gratings.

Monolithic DBR-type fullband tunable lasers

“…By the correct choice of the number and positions of the phase shifts the response of the grating can be tailored to produce a top-hat comb of reflection peaks of arbitrary number and of equal height and spacing. The design of a phase grating is best accomplished using automated optimization [8]. For the DS-DBR laser we have used such an approach to design a phase grating with seven reflection peaks, spaced at 6.8nm.…”

“…The DS-DBR laser uses two very different gratings in its design, one chirped grating at the front of the device and one phase grating at the rear. The phase grating [8,9] consists of a number of lengths of uniform grating separated by π-phase shifts. By the correct choice of the number and positions of the phase shifts the response of the grating can be tailored to produce a top-hat comb of reflection peaks of arbitrary number and of equal height and spacing.…”

Widely Tunable Semiconductor Laser Based on Digital Concatenated Grating With Multiple Phase Shifts

“…Tunable lasers are also key components in future optical packet and burst (OPS/OBS) switching systems to reduce the latency and increase the capacity of current optical transmission networks [2], [3]. Several typical tunable lasers have been demonstrated including the sampled-grating (SG) or superstructure grating (SSG) distributed Bragg reflector (DBR) lasers [4], [5], the grating assisted co-directional coupler with rear sampled grating reflector (GCSR) lasers [6], the digital supermode (DS) DBR lasers [7] with phase gratings [8], [9], the binary superimposed grating (BSG) DBR lasers [10] and the modulated grating Y-branch (MGY) lasers [11]. In addition, to provide a Bflat-top[ comb reflector which is ideal for tunable lasers, we have proposed the wavelength tunable digital concatenated grating (DCG) DBR laser [12].…”