1. A microwave oven comprising:
a cavity for accommodating food to be cooked, of which at least one side defining an opening;
a door for shielding the opening selectively;
a magnetron disposed at an outside of the cavity, for generating microwave;
a waveguide for guiding the generated microwave into the cavity;
a stirrer fan disposed at an outlet of the waveguide, for scattering the microwave guided by the waveguide;
a motor fixed at an outside of the waveguide and having a shaft connected with the stirrer fan;
a screw covering part formed by modifying a portion of the waveguide to accommodate a motor fixing screw;
a convergence preventing part formed at a portion of the cavity, the convergence preventing part having a shape corresponding to the screw covering part and provided at a location corresponding to the screw covering part; and
an elevated portion formed by modifying a portion of the cavity, for uniformly distributing the microwave scattered by the stirrer fan.
2. The microwave oven according to claim 1, wherein the waveguide is provided at an upper side andor a lower side of the microwave oven.
3. The microwave oven according to claim 1, wherein the convergence preventing part is formed with a recessed shape toward an inside of the cavity.
4. The microwave oven according to claim 1, wherein the convergence preventing part is formed around the stirrer fan at the corresponding location.
5. The microwave oven according to claim 1, wherein the elevated portion protrudes toward an inside of the cavity.
6. The microwave oven according to claim 1, wherein the elevated portion is formed at an outside of the stirrer fan.
7. The microwave oven according to claim 1, wherein the elevated portion has a substantially hemispheric shape.
8. The microwave oven according to claim 1, wherein the number of the elevated portion is plural and the plurality of elevated portions are arranged facing each other around the stirrer fan.
9. The microwave oven according to claim 1, wherein the elevated portion is integrally formed with a plate of the cavity.
10. The microwave oven according to claim 1, wherein a vertical distance between the screw covering part and the convergence preventing part is equal to a vertical distance between the cavity and the waveguide.
11. A microwave radiating structure of a microwave oven comprising:
a magnetron disposed at an outside of a cavity, for generating microwave;
a waveguide for guiding the generated microwave into the cavity;
a stirrer fan disposed at an outlet of the waveguide, for scattering the microwave guided by waveguide;
a motor fixed at an outside of the waveguide and having a shaft connected with the stirrer fan; and
a convergence preventing part provided at a nearby position of the motor, the convergence preventing part being recessed toward an inside of the cavity, wherein the waveguide is modified to form a screw covering part at a position where the motor is fixed, and the convergence preventing part is formed to have a shape corresponding to the screw covering part and being provided at a location corresponding to the screw covering part.
12. The microwave radiating structure according to claim 11, wherein the number of the convergence preventing part is plural and the convergence preventing parts are arranged around the stirrer fan at the corresponding locations.
13. The microwave radiating structure according to claim 11, wherein the stirrer fan is provided at an upper side andor lower side of the cavity.
14. The microwave radiating structure according to claim 11, wherein the convergence preventing part is formed by modifying the waveguide.
15. The microwave radiating structure according to claim 11, wherein a vertical distance between the screw covering part and the convergence preventing part is equal to a vertical distance between the cavity and the waveguide.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A Raman amplifier, comprising:
a plurality of pump lasers, each pump laser arranged in a respective control loop for keeping a power of a respectively associated pump signal constant; and
a wavelength division multiplexer, wherein the pump signals are combined via the wavelength division multiplexer and are fed to a transmission fiber.
2. A Raman amplifier as claimed in claim 1, wherein each control loop further comprises an optical filter connected in series with the respectively associated pump laser for frequency stabilization.
3. A Raman amplifier as claimed in claim 1, wherein each control loop further comprises a polarization mixer connected in series with the respectively associated pump laser.
4. A Raman amplifier as claimed in claim 1, wherein each control loop further comprises a measurement coupler, a monitor diode and a regulator, such that the measurement coupler and the monitor diode control the power of the respectively associated pump signal, and a measurement signal controls an injection current of the respectively associated pump laser via the regulator.
5. A Raman amplifier as claimed in claim 1, wherein the Raman amplifier is operated in a linear area.
6. A Raman amplifier as claimed in claim 1, wherein power levels of the pump signals are set such that the Raman amplifier has a desired gain profile in a relevant wavelength band.
7. A Raman amplifier as claimed in claim 4, further comprising:
a controller for providing reference variables for all of the regulators and for setting the power levels of the pump signals for an optimum gain profile based on stored or externally supplied data or signals.
8. A Raman amplifier as claimed in claim 7, wherein the controller includes an input for a busy signal, which indicates active transmission bands, and uses stored tables to activate and switch off some of the pump lasers and sets the power levels of the pump signals for an optimum gain profile.
9. A Raman amplifier as claimed in claim 7, wherein the controller controls switching of the signal levels in the event of one of failure and a changed connection state of a transmission band.