Abstract: A super-compact arrayed waveguide grating (AWG) wavelength division multiplexer based on a sub-wavelength grating is provided and includes an input waveguide, a first planar waveguide, an arrayed waveguide, a second planar waveguide, and the output waveguide that are sequentially connected. The input waveguide has 1 port, and the output waveguide has 8 ports. The arrayed waveguide includes 50 equivalent uniform strip waveguides with the same length difference, and each of the equivalent uniform strip waveguides is configured as a sub-wavelength grating structure, thereby forming the effect of increasing group refractive index or transmission delay based on a slow light effect. The 8 channels with a channel spacing of 200 GHz have the minimum adjacent channel crosstalk of less than ?27 dB, and the overall size is within 300×230 ?m2. In the multiplexer, the overall integration size of the device is reduced by an order of magnitude.

Abstract: An integrated photonics millimeter wave (MMW) radar communication system based on analog phase modulation scheme includes an integrated photonics MMW radar communication signal transmitter, a radar receiver, and a communication receiver. The transmitter includes a radar communication signal analog phase modulation module, an optical frequency comb (OFC) module, an electro-optic modulator (EOM), an optical shaping filter, an optical power divider, a photoelectric detector, an electric power amplifier, and a transmitting antenna that are cascaded sequentially. The radar receiver includes a radar receiving antenna, an electric low-noise amplifier (LNA), an optical phase modulator, an optical bandpass filter (BPF), a low-speed photoelectric detector, an electric low-pass filter, and a low-speed oscilloscope that are cascaded sequentially.

Abstract: A super-compact arrayed waveguide grating (AWG) wavelength division multiplexer based on a sub-wavelength grating is provided and includes an input waveguide, a first planar waveguide, an arrayed waveguide, a second planar waveguide, and the output waveguide that are sequentially connected. The input waveguide has 1 port, and the output waveguide has 8 ports. The arrayed waveguide includes 50 equivalent uniform strip waveguides with the same length difference, and each of the equivalent uniform strip waveguides is configured as a sub-wavelength grating structure, thereby forming the effect of increasing group refractive index or transmission delay based on a slow light effect. The 8 channels with a channel spacing of 200 GHz have the minimum adjacent channel crosstalk of less than -27 dB, and the overall size is within 300×230 µm2. In the multiplexer, the overall integration size of the device is reduced by an order of magnitude.

Abstract: A coherent detection-based high-speed chaotic secure transmission method includes: at a transmit terminal in a chaotic secure transmission system, optically coupling an optical chaotic carrier and transmission information by using an orthogonal basis to mask the transmission information by using a noise-like feature of the chaotic carrier, so as to obtain a chaotic masked signal; adding a fast phase disturbance and a fast polarization disturbance to the chaotic masked signal and transmitting the chaotic masked signal over an optical fiber transmission link; and at a receive terminal, obtaining the chaotic masked signal through coherent detection, compensating the chaotic masked signal for linear and nonlinear effects through digital signal processing, and using a polarization orthogonal basis- or phase orthogonal basis-based chaotic decryption algorithm to separate the chaotic carrier from the signal so as to complete decryption.

Abstract: Devices, systems and techniques for optical communication are provided based on polarization division multiplexing (PDM) to use an optical monitor channel at a distinct optical monitor wavelength to monitor optical polarization fluctuation and polarization mode dispersion during the transmission from the transmitter to the receiver to facilitate the effective demultiplexing of the two orthogonal signal channels at the receiver through automatic feedback control on a dynamic polarization controller and a polarization beam splitter.

Abstract: Systems, apparatus and methods for characterizing linear retarders using a waveplate analyzer constructed by polarization rotators. In one implementation of such an analyzer, both the retardation of the waveplate sample and the orientation of optical axis of the waveplate sample can be simultaneously measured.

Abstract: Apparatus and methods for scrambling optical modes in multimode fibers to achieve uniform light distribution in guided multi-mode light for various applications.

Abstract: Apparatus and methods for scrambling optical modes in multimode fibers to achieve uniform light distribution in guided multi-mode light for various applications.

Abstract: Differential group delay (DGD) devices and techniques based on folded optical paths. An in-line polarization monitor can be provided as a feedback for worst-case alignment without using an in-line polarizer. Polarization maintaining retro reflectors can minimize the introduced higher-order polarization effects caused by reflections between folding mirrors or prisms in conventional schemes.

Abstract: Devices and their operations to use multiple adjustable differential group delay (DGD) elements in various applications including tunable PMD emulators and compensators for producing different PMD profiles with an adjustable average DGD value.

Abstract: Techniques and devices that use polarization rotation and optical interferometry to provide optical spectrum analysis of an optical signal.

Abstract: Devices and techniques for generating and analyzing states of polarization in light using multiple adjustable polarization rotators in various applications.

Abstract: Apparatus, systems and techniques for optical communication based on polarization division multiplexing (PDM) using an optical monitor channel to facilitate the effective demultiplexing of the two orthogonal signal channels through automatic feedback control on a dynamic polarization controller and a polarization beam splitter.

Abstract: A multi-wavelength optical signal copropagates through a fiber-optic communication link with a continuous-wave ancillary wavelength having an unknown state of polarization (SOP), which is scrambled periodically in time. The instantaneous value of polarization dependent loss (PDL) in the ancillary wavelength is monitored in real time, and is used as an error signal to adjust at least one polarization controller. Polarization scrambling is performed by periodically changing the SOP with time, such that the polarization-scrambled optical signal covers approximately an entire Poincaré sphere surface, preferably uniformly, during each time period. At an optical node between fibers, an adjustable PDL compensator contains two ordered pairs each consisting of one polarization controller and one optical element introducing fixed PDL.

Abstract: Devices and techniques for generating and analyzing states of polarization in light using multiple adjustable polarization rotators in various applications.

Abstract: Tunable PMD emulators and compensators for producing different PMD profiles with an adjustable average DGD value.

Abstract: A multi-wavelength optical signal copropagates through a fiber-optic communication link with a continuous-wave ancillary wavelength having an unknown state of polarization (SOP), which is scrambled periodically in time. The instantaneous value of polarization dependent loss (PDL) in the ancillary wavelength is monitored in real time, and is used as an error signal to adjust at least one polarization controller. Polarization scrambling is performed by periodically changing the SOP with time, such that the polarization-scrambled optical signal covers approximately an entire Poincaré sphere surface, preferably uniformly, during each time period. At an optical node between fibers, an adjustable PDL compensator contains two ordered pairs each consisting of one polarization controller and one optical element introducing fixed PDL.

Abstract: Autocorrelation technique for measurement of width of optical short pulses based on polarization effects. The optical pulse is split into two orthogonal polarization states and these two replicas have a relative delay which depolarizes the pulse. By tuning the relative delay of the two replicas and measuring the degree-of-polarization (DOP) of the pulse or the induced polarimetric four-wave mixing (FWM) through nonlinear media, the pulse's temporal width can be accurately derived. The technique can be all-fiber-based, wavelength independent, cost effective, applicable to low optical power, and does not require significant optical alignment.

Abstract: Techniques and systems for dynamically controlling polarization of an optical signal by using various feedback controls, and by combining both feed-forward and feedback controls. Various dynamic control algorithms for such systems and other optical systems have been disclosed.

Abstract: Techniques for monitoring frequency-dependent parameter and optical property such as optical dispersion in a modulated optical signal with sidebands based on optical vestigial sideband filtering. Monitoring implementations for both chromatic dispersion and polarization-mode dispersion are described as examples.