摘要:
A laser device (1) comprises a ridge waveguide (2) comprising an upper cladding layer (5) and a lower cladding layer (6), between which is located an active layer (7). A ridge (8) formed in the upper cladding layer (5) defines the lateral width of a light guiding region (9) in the active layer (7). The ridge (8) is formed so that a portion (13) of the light guiding region (9) extends above the active layer (7) into the ridge (8). A plurality of lateral reflecting slots (15) extend laterally across the ridge (8) and extend into the ridge (8) to a depth sufficient to extend into the portion (13) of the light guiding region (9) which extends into the ridge (8) in order that the reflectivity of each lateral slot (15) is in the order of 2%. The combined reflectivity of the lateral slots (15) is such that the slots (15) intersect more than 20% of the total mode energy in the light guiding region (9), and this in combination with the gain of the active layer (7) is such as to facilitate lasing within the light guiding region (9) independently of the reflectivity of end facets (18,19) of the waveguide (2). Accordingly, the laser device (1) is particularly suitable for integrally forming with other optical components, for example, an optical modulator or an optical detector on a single semiconductor chip, whereby the laser device and the other optical components are formed in series on the same light guiding region (9).
摘要:
A tunable laser device (1) comprises integrally formed first and second ridge waveguides (5, 6). A longitudinally extending ridge (12) defines first and second light guiding regions (19, 20) of the first and second waveguides (5, 6) A plurality of first and second slots (27, 28) extending laterally in the ridge (12) adjacent the first and second waveguides (5, 6), produce first and second mirror loss spectra of the respective first and second waveguides (5, 6) with minimum peak values at respective first and second wavelength values. The spacing between the second slots (28) is different to that between the first slots (27) so that with one exception the minimum peak values of the first and second mirror loss spectrum occur at different wavelength values. The first and second waveguides (5, 6) are independently pumped with variable currents to selectively vary the common wavelength at which the minimum peak values of the first and second mirror loss spectra occur to produce Vernier tuning of the device.
摘要:
A tunable laser device (1) comprises integrally formed first and second ridge waveguides (5, 6). A longitudinally extending ridge (12) defines first and second light guiding regions (19, 20) of the first and second waveguides (5, 6) which communicate with each other. A plurality of first slots (27) extending laterally in the ridge (12) adjacent the first waveguide (5), and a plurality of second slots (28) extending laterally in the ridge (12) adjacent the second waveguide (6) produce first and second mirror loss spectra of the respective first and second waveguides (5, 6) with minimum peak values at respective first and second wavelength values. The first slots are equi-spaced apart to produce the first mirror loss spectrum, and the second slots (28) are also equi-spaced apart, but the spacing between the second slots (28) is different to the spacing between the first slots (27) so that the minimum peak values of the second mirror loss spectrum occur at different wavelength values to the wavelength values at which the minimum peak values of the first mirror loss spectrum occur, with the exception of one minimum peak value of each of the first and second mirror loss spectra, which coincide at a common wavelength value. The tunable laser device (1) produces light of that common wavelength value. In order to vary the wavelength value at which the minimum peak value of each of the first and second mirror loss spectra occur, currents with which the first and second waveguides (5, 6) are pumped are independently varied for varying the wavelengths at which the minimum peak values of the respective first and second mirror loss spectra occur, thereby providing Vernier tuning of the tunable laser device for producing light of selectable wavelengths.
摘要:
An initial epitaxial layer of GaN is grown on a sapphire substrate. The epitaxial layer is then etched in a reactive ion etch (RIE) chamber. This etching acts preferentially at defects, causing them to become enlarged cavities. The cavities are too large in proportion to the crystal lattice to act as defects in the usual sense, and so a further GaN epitaxial layer fills into the cavities. Thus, propagation of defects is avoided.