The present invention provides self-collimating multiwavelength lasers (MWL) including a planar gain medium with a resonance cavity defined by superimposed gratings. These laser devices are characterized by lasing wavelengths with multiple peaks in their reflectance spectra defined by the superimposed gratings. The gratings also limit beam divergence, producing self-collimated multiwavelength output, with the potential for high power. These devices can be implemented in any planar gain medium in which multi-peak gratings can be produced, including but not limited to semiconductors and doped glasses. The self-collimated MWL's disclosed herein have applications in areas such as DWDM (dense wavelength division multiplexing) communications systems, free-space uses such as interconnects, range-finding, and inter-satellite infrared communication. In one aspect the device is a multiwavelength ring cavity laser including a planar gain medium with two orthogonal pairs of supergratings (SG) A and B, which emulate the superposition of M and N single-pitch gratings respectively. SG-A has a set of M diffraction wavelengths that depends on the incident angle .theta.; a similar dependence on .phi.=.theta.-90.degree. exists for the set of N diffraction wavelengths of SG-B. Wavelength-angle pairs common to both SG-A and SG-B will be resonant within the cavity as a whole. When combined with optical gain, the result is lasing at M by N wavelengths, collimated at a well-defined output angle.
CROSS REFERENCE TO RELATED U.S. PATENT APPLICATION
This application relates to U.S. Provisional patent application, Ser. No. 60/081,964, filed on Apr. 16, 1998, entitled MULTIWAVELENGTH SELF-COLLIMATING LASERS.
A laser diode array that includes a plurality of laser stripes each separated by an unpumped region. The array includes at least one first laser stripe and at least one second laser stripe. The first laser stripe emits a first laser beam. The second laser stripe emits a second laser beam. A phase shifter is connected to the stripes so that the phase of the second laser beam is shifted to be in phase with first laser beam. The resultant output beam of the array is a high power, high quality, diffraction limited beam.
A laser system capable of producing multiple groups of output wavelengths is disclosed. In one embodiment, an optical fiber bundle doped with erbium (Er) or erbium/ytterbium (Er/Yb) is perpendicularly attached to an optical device, which serves as a guided-mode resonance feedback mirror, to form a fiber laser matrix. The optical device contains a substrate layer, a waveguide layer, and a grating layer, with non-uniform device parameters. The wavelength of the resonant light and its corresponding laser light of an individual optical fiber depends upon the parameters in the location on the optical device where the fiber is attached. In another embodiment, a plurality of active waveguides in a body are attached to an optical device to form a diode-pumped crystal laser matrix with multi-group output wavelengths. The invented laser system is capable of generating laser sources of large channel capacity for the optical network especially for the dense wavelength division multiplexing (DWDM) system.
A tunable lasing device (100) comprising a ring-shaped laser cavity (102), an optical gain element (104), a bi-directional output coupler (106) and a frequency selection means (114). The frequency selection means is generally a grating with a refractive index that determines a grating reflection frequency. Single mode laser operation is achieved where a cavity mode frequency of the ring-shaped laser cavity coincides with a grating reflection frequency. The refractive index of the grating can be modified by the injection of a variable current. In this way, the lasing frequency can be rapidly tuned between cavity mode frequencies.
The present invention provides a continuously tunable external cavity laser (ECL) with a compact form factor and precise tuning to a selected center wavelength of a selected wavelength grid. The ECL may thus be utilized in telecom applications to generate the center wavelengths for any channel on the ITU or other optical grid. The ECL does not require a closed loop feedback. A novel tuning mechanism is disclosed which provides for electrical or mechanical tuning to a known position or electrical parameter, e.g., voltage, current or capacitance, with the required precision in the selected center wavelength arising as a result of a novel arrangement of a grid generator and a channel selector. The grid generator exhibits first pass bands which correspond to the spacing between individual channels of the selected wavelength grid and a finesse which suppresses side band modes of the laser. The channel selector exhibits second pass bands differing from the first transmission bands by an amount corresponding substantially inversely with the number of channels of the selected wavelength grid. This relationship allows "vernier" tuning of the output wavelength of the laser to a selected wavelength on the wavelength grid. The finesse of the grid generator and channel selector is chosen to suppress channels adjacent to the selected channel. In an alternate embodiment of the invention a gain medium operable as a grid generator is disclosed. In an alternate embodiment of the invention a method for tuning a laser is disclosed.
The present invention relates to the tailoring the reflectivity spectrum of a SGDBR by applying digital sampling theory to choose the way each reflector is sampled. The resulting mirror covers a larger wavelength span and has peaks with a larger, more uniform, coupling constant (.kappa.) than the mirrors produced using conventional approaches. The improved mirror also retains the benefits of the sample grating approach. Additionally, most of the embodiments are relatively simple to manufacture.
