Thermal compensators for waveguide DBR laser sources

A waveguide DBR light emitting device comprising:

• a semiconductor gain element having a rear reflecting facet and a substantially nonreflecting exit facet;
• an optical waveguide having an input end optically coupled to said gain element via said exit facet;
• a grating having a grating period associated with said optical waveguide to provide feedback to said gain element;
• and
• means to adjust the refractive index of said gain element to provide operation freedom of the device from longitudinal mode hopping.

A waveguide DBR light emitting device comprising:

• a semiconductor gain element having a reflecting rear facet and a substantially antireflecting exit facet;
• at least two electrical contacts formed on a surface of said gain element;
• means to adjust the current supplied to said contacts independently of one another;
• an optical waveguide having an input end optically coupled to said gain element via said exit facet;
• reflection means associated with said optical waveguide to provide feedback to said gain element.

A waveguide DBR light emitting device for single wavelength, high speed modulated operation comprising:

• a semiconductor gain element having a reflecting rear facet and a substantially antireflecting exit facet;
• an optical waveguide having an input end optically coupled to said gain element via said exit facet;
• a waveguide grating formed in said optical waveguide in close proximity to said exit facet forming a resonant cavity between said gain element rear facet, lengths of said resonant cavity, gain element and waveguide grating chosen to satisfy the relationship of:
• ##EQU10## where L.sub.BW is the length of optical bare waveguide between the antireflecting exit facet and the waveguide grating, L.sub.G is the length of the waveguide grating, L.sub.GE is the length of the gain element, K is the coupling constant of the waveguide grating, v.sub.GE is the relaxation oscillation frequency of the gain element, v.sub.DBR is the relaxation oscillation frequency of the resonant cavity, n.sub.GE is the effective refractive index of the gain element, and n.sub.W is the effective refractive index of the optical waveguide.

A waveguide DBR laser device comprising:

• a semiconductor gain element having a reflecting rear facet and a substantially antireflecting exit facet;
• an optical waveguide having an input end optically coupled to said gain element via said exit facet;
• a waveguide grating having a predetermined grating period formed in said optical waveguide in close proximity to said exit facet forming a resonant cavity between said rear facet and said grating;
• and
• means to vary the period of said grating to stabilize wavelength operation of the device between adjacently competing longitudinal modes of operation at a given operating temperature.

A waveguide DBR laser device comprising:

• a semiconductor gain element having a reflecting rear facet and a substantially antireflecting exit facet;
• an optical waveguide having an input end optically coupled to said gain element via said exit facet;
• a waveguide grating having a predetermined grating period formed in said optical waveguide in close proximity to said exit facet forming a resonant cavity between said rear facet and said grating;
• and
• means to vary the path length of said optical waveguide to stabilize the operation of said laser device between adjacent longitudinal modes of operation.

A waveguide DBR laser device for single longitudinal mode, high speed operation comprising:

• a semiconductor gain element having a reflecting rear facet and a substantially antireflecting exit facet;
• an optical waveguide having an input end optically coupled to said gain element via said exit facet;
• a waveguide grating having a predetermined grating period formed in said optical waveguide in close proximity to said exit facet forming a resonant cavity between said rear facet and said grating;
• wherein the ratio of the effective length of said waveguide to the length of said gain element is adjusted to maximize the achievable modulation rate of said gain element.

A waveguide DBR laser device for single longitudinal mode, high speed operation for modulation in excess of 2 Gb/sec comprising:

• a semiconductor gain element having a high reflecting rear facet and antireflecting exit facet;
• an optical waveguide having an input end optically coupled to said gain element via said exit facet;
• a waveguide grating having a predetermined grating period formed in said optical waveguide in close proximity to said input end forming a resonant cavity between said rear facet and said grating;
• and
• stabilization means to prevent longitudinal mode hopping between longitudinal modes of operation in said resonant cavity.

A waveguide DBR laser device for single longitudinal mode, high speed operation for modulation in excess of 2 Gb/sec comprising:

• a semiconductor gain element having a high reflecting rear facet and antireflecting exit facet;
• an optical waveguide having an input end optically coupled to said gain element via said exit facet;
• a waveguide grating having a grating period formed in said optical waveguide in close proximity to said exit facet forming a resonant cavity between said rear facet and said grating;
• and
• adjustment means to maintain lasing operation within said resonant cavity between adjacent longitudinal modes of operation.

A waveguide DBR laser device comprising:

• at least one semiconductor gain element having a reflecting rear facet and a substantially antireflecting exit facet with a plurality of emitters each capable of single longitudinal mode, high speed operation for modulation in excess of 2 Gb/sec;
• a plurality of optical waveguides each having an input end optically coupled to a respective emitter of said gain element via said exit facet;
• waveguide grating having a grating period formed in each of said optical waveguide in close proximity to said exit facet forming a plurality of resonant cavities between said rear facet and said respective gratings;
• each of said grating periods set such that each of the resonant cavities operate at a different wavelength;
• stabilization means to prevent longitudinal mode hopping in the resonant cavities between longitudinal modes;
• means to independently modulate at least some of said gain elements providing a modulated signal representative of information;
• and
• WDM means for combining individual outputs of said resonant cavities forming a single output of multiple modulated signals.

A method of operating a waveguide DBR laser device to achieve stable single longitudinal mode operation wherein the device includes a gain element having exit output and rear facets with radiation from the exit output facet coupled to an external cavity comprising an optical waveguide and a grating having a predetermined grating period formed in said waveguide to form a resonator cavity between the rear facet of the gain element and the waveguide grating capable of mode hopping between longitudinal modes of operation, the method comprising the steps of:

• determining positions of longitudinal mode hops in operation of the device over a range of applied current;
• choosing an operating temperature for the device so that it operates within a window of operation between determined longitudinal mode hops within an intended range of current operation of the device;
• and
• trimming the refractive index of the optical waveguide so that the wavelength behavior of the laser remains within the window.

A method of operating a waveguide DBR laser device to achieve stable single longitudinal mode operation wherein the device includes a gain element having exit output and rear facets with radiation from the exit output facet coupled to an external cavity comprising an optical waveguide and a grating having a predetermined grating period formed in said waveguide to form a resonator cavity between the rear facet of the gain element and the waveguide grating capable of mode hopping between longitudinal modes of operation, the method comprising the steps of:

• operating the waveguide DBR laser device below its lasing threshold of operation maximizing the coupling of laser spontaneous emission into the optical waveguide;
• determining positions of longitudinal mode hops in operation of the device over a range of applied current;
• and
• choosing an operating temperature for the device so that it operates within a window of operation between determined longitudinal mode hops within an intended range of current operation of the device.