Semiconductor laser
First Claim
1. In a monomode semiconductor laser having a multilayer structure disposed between first and second electrodes for an injection current and wherein an interface between a waveguide layer and an adjacent layer is configured as a diffraction grating, the improvement wherein the diffraction grating is composed of at least two different superposed subgratings which each have a different grating constant and which each extend over the entire region of said interface disposed between said first and second electrodes, whereby said laser is switchable between at least two different emission wavelengths.
2 Assignments
0 Petitions
Accused Products
Abstract
A switchable DFB (distributed feedback) laser which includes a waveguide layer having an impressed diffraction grating composed of two or more superposed subgratings having different respective grating constants. The diffraction grating is either frequency modulated (FIG. 3a) or amplitude modulated (FIG. 3b) or is a mixed form of these two types of modulation. Each subgrating can be employed to generate an emission wavelength that is a function of the grating period. By changing the temperature or changing the injection current, the effective index of refraction of the laser is changed, thus enabling the setting of an emission wavelength which is a function of the modulated diffraction grating. The switchable DFB laser according to the present invention may be employed for optical data transmission and particularly in narrowband wavelength multiplex operation.
-
Citations
12 Claims
- 1. In a monomode semiconductor laser having a multilayer structure disposed between first and second electrodes for an injection current and wherein an interface between a waveguide layer and an adjacent layer is configured as a diffraction grating, the improvement wherein the diffraction grating is composed of at least two different superposed subgratings which each have a different grating constant and which each extend over the entire region of said interface disposed between said first and second electrodes, whereby said laser is switchable between at least two different emission wavelengths.
Specification