Abstract: The present invention relates to a constructing method and device for an optical passive component by using an improved structure of a Mach-Zehnder interferometer. This improved structure of the Mach-Zehnder interferometer is composed of two MMI beam splitters, a curved channel waveguide and a periodic segment waveguide for being separately used as the beam-splitting components, the curved arm and the straight arm of the Mach-Zehnder interferometer. In the inventive MMI beam splitter, a sub-area in the MMI waveguide is a periodic segment waveguide having a plurality of segments. By adjusting the number of the segments of the periodic segment waveguide in the MMI waveguide, the beam-splitting ratio of the MMI beam splitter can be arbitrarily adjusted. By adjusting the segment period and the duty cycle of the straight arm of the Mach-Zehnder interferometer, the required length of the straight arm can be efficiently shortened.

Abstract: An apparatus and method for simultaneous channel and optical signal-to-noise ratio (OSNR) monitoring is adapted to function in multi-channel wavelength-division-multiplexed (WDM) optical communication systems. A polarization controller is sequentially adjusted to perform the sequential polarization control with an optical signal. A polarization-selective electro-optic modulator acts as a polarizer and provides a signal dithering to improve the detection sensitivity. A beam splitter splits the dithered optical signal into two clusters. A photodetector receives the first cluster and measures the OSNR. An optical element receives the second cluster and recognizes the channel wavelength of multiple channels. The apparatus can be packaged into a compact module and integrated on a chip. The channel monitoring covers a wide wavelength range and is tunable. The OSNR monitoring can be accurate over a wide dynamic range.

Abstract: There are disclosed a wavelength monitoring device of tunable laser sources and a method thereof. A Fabry-Perot etalon is provided to detect the wavelength drift, and furthermore, a Fabry-Perot laser diode or a light emitting diode is provided to recognize the channel of the wavelength. The wavelength drift is used to determine the junction voltage of each corresponding channel in advance. Then, the actually detected junction voltage of the diode is used to determine the channel of the wavelength, thereby accurately detecting the actual channel wavelength.

Abstract: This invention demonstrates an adjustable monolithic multi-wavelength laser diode array formed on a substrate a plurality of diode lasers, each has an active section and two mirrors with similar multiple reflectivity peaks. A phase control section can also be included in each laser for fine tuning of the laser wavelength. Each laser in the laser array can emit light at the same wavelength or can be easily tuned to form an array with multiple wavelengths. To serve as an application example of this invention, sampled grating DBR lasers are designed to form a laser array with adjustable multi-wavelength outputs. By varying from laser to laser the sampling periods of the sampled gratings in each laser, a uniformly-spaced multi-wavelength laser array can be achieved with a simple tuning mechanism. The lasers can also emit light at the same wavelength or be tuned to other wavelengths by tuning the sampled grating mirrors.

Abstract: This invention demonstrates the methods that use semiconductor laser amplifier (SLA) as a wavelength discriminator, as well as several apparatus designed using these methods. The functions of the invented apparatus include wavelength measurement, wavelength tracking, wavelength comparison, and wavelength stabilization and control of lasers. The key concept for which these methods and apparatus work is the variation of the transparent current of a SLA with the wavelength of an incident light. The transparent current of a SLA can be easily detected from the induced voltage across the diode junction when the incident light is intensity-modulated. The incident wavelength can be accurately determined by measuring the transparent current. These methods and apparatus are expected to be very useful in wavelength display for photonic instruments, wavelength control and wavelength registration for photonic networks, and wavelength stabilization for laser diodes.