摘要:
An SOI-based opto-electronic structure includes various electronic components disposed with their associated optical components within a single SOI layer, forming a monolithic arrangement. EMI/EMC shielding is provided by forming a metallized outer layer on the surface of an external prism coupler that interfaces with the SOI layer, the metallized layer including transparent apertures to allow an optical signal to be coupled into and out of the SOI layer. The opposing surface of the prism coupler may also be coated with a metallic material to provide additional shielding. Further, metallic shielding plates may be formed on the SOI structure itself, overlying the locations of EMI-sensitive electronics. All of these metallic layers are ultimately coupled to an external ground plane to isolate the structure and provide the necessary shielding.
摘要:
A planar optical isolator is formed within the silicon surface layer of an SOI structure. A forward-directed signal is applied to an input waveguiding section of the isolator and thereafter propagates through a non-reciprocal waveguide coupling region into an output waveguide section. A rearward-directed signal enters via the output waveguide section and is thereafter coupled into the non-reciprocal waveguide structure, where the geometry of the structure functions to couple only a small amount of the reflected signal into the input waveguide section. In one embodiment, the non-reciprocal structure comprises an N-way directional coupler (with one output waveguide, one input waveguide and N-1 isolating waveguides). In another embodiment, the non-reciprocal structure comprises a waveguide expansion region including a tapered, mode-matching portion coupled to the output waveguide and an enlarged, non-mode matching portion coupled to the input waveguide such that a majority of a reflected signal will be mismatched with respect to the input waveguide section. By cascading a number of such planar SOI-based structures, increased isolation can be achieved—advantageously within a monolithic arrangement.
摘要:
An arrangement for providing optical crossovers between waveguides formed in an SOI-based structure utilize a patterned geometry in the SOI structure that is selected to reduce the effects of crosstalk in the area where the signals overlap. Preferably, the optical signals are fixed to propagate along orthogonal directions (or are of different wavelengths) to minimize the effects of crosstalk. The geometry of the SOI structure is patterned to include predetermined tapers and/or reflecting surfaces to direct/shape the propagating optical signals. The patterned waveguide regions within the optical crossover region may be formed to include overlying polysilicon segments to further shape the propagating beams and improve the coupling efficiency of the crossover arrangement.
摘要:
An arrangement for achieving and maintaining high efficiency coupling of light between a multi-wavelength optical signal and a relatively thin (e.g., sub-micron) silicon optical waveguide uses a prism coupler in association with an evanescent coupling layer. A grating structure having a period less than the wavelengths of transmission is formed in the coupling region (either formed in the silicon waveguide, evanescent coupling layer, prism coupler, or any combination thereof) so as to increase the effective refractive index “seen” by the multi-wavelength optical signal in the area where the beam exiting/entering the prism coupler intercepts the waveguide surface (referred to as the “prism coupling surface”). The period and/or duty cycle of the grating can be controlled to modify the effective refractive index profile in the direction away from the coupling region so as to reduce the effective refractive index from the relatively high value useful in multi-wavelength coupling to the lower value associated with maintaining confinement of the optical signals within the surface waveguide structure, thus reducing reflections along the transition region.
摘要:
A coupling arrangement for allowing multiple wavelengths to be coupled into and out of a relatively thin silicon optical waveguide layer utilizes a diffractive optical element, in the form of a volume phase grating, in combination with a prism coupling structure. The diffractive optical element is formed to comprise a predetermined modulation index sufficient to diffract the various wavelengths through angles associated with improving the coupling efficiency of each wavelength into the silicon waveguide. The diffractive optical element may be formed as a separate element, or formed as an integral part of the coupling facet of the prism coupler.
摘要:
An HDMI interconnect arrangement is presented that performs a pulse-amplitude modulation (PAM) conversion of the TMDS audio/video signals in order to simultaneously transmit all three channels over a single optical fiber. The set of three audio/video TMDS channels is applied as an input to a PAM-8 optical modulator, which functions to encode the set of three channels onto an optically-modulated output signal. The modulated optical signal is thereafter coupled into an optical fiber within an active HDMI cable and transmitted to an HDMI receiver (sink). The TMDS CLK signal is not included in this conversion into the optical domain, but remains as a separate electrical signal to be transmitted along a copper signal path within the active HDMI cable.
摘要:
An HDMI interconnect arrangement is presented that performs a pulse-amplitude modulation (PAM) conversion of the TMDS audio/video signals in order to simultaneously transmit all three channels over a single optical fiber. The set of three audio/video TMDS channels is applied as an input to a PAM-8 optical modulator, which functions to encode the set of three channels onto an optically-modulated output signal. The modulated optical signal is thereafter coupled into an optical fiber within an active HDMI cable and transmitted to an HDMI receiver (sink). The TMDS CLK signal is not included in this conversion into the optical domain, but remains as a separate electrical signal to be transmitted along a copper signal path within the active HDMI cable.
摘要:
An arrangement for providing optical crossovers between waveguides formed in an SOI-based structure utilize a patterned geometry in the SOI structure that is selected to reduce the effects of crosstalk in the area where the signals overlap. Preferably, the optical signals are fixed to propagate along orthogonal directions (or are of different wavelengths) to minimize the effects of crosstalk. The geometry of the SOI structure is patterned to include predetermined tapers and/or reflecting surfaces to direct/shape the propagating optical signals. The patterned waveguide regions within the optical crossover region may be formed to include overlying polysilicon segments to further shape the propagating beams and improve the coupling efficiency of the crossover arrangement.
摘要:
An electro-optic modulator arrangement for achieving switching speeds greater than 1 Gb/s utilizes pre-emphasis pulses to accelerate the change in refractive index of the optical waveguide used to form the electro-optic modulator. In one embodiment, a feedback loop may be added to use a portion of the modulated optical output signal to adjust the magnitude and duration of the pre-emphasis pulses, as well as the various reference levels used for modulated. For free carrier-based electro-optic modulators, including silicon-based electro-optic modulators, the pre-emphasis pulses are used to accelerate the movement of free carriers at the transitions between input signal data values.
摘要:
An SOI-based photonic bandgap (PBG) electro-optic device utilizes a patterned PBG structure to define a two-dimensional waveguide within an active waveguiding region of the SOI electro-optic device. The inclusion of the PBG columnar arrays within the SOI structure results in providing extremely tight lateral confinement of the optical mode within the waveguiding structure, thus significantly reducing the optical loss. By virtue of including the PBG structure, the associated electrical contacts may be placed in closer proximity to the active region without affecting the optical performance, thus increasing the switching speed of the electro-optic device. The overall device size, capacitance and resistance are also reduced as a consequence of using PBGs for lateral mode confinement.