Optical devices for wavebands for coarse wavelength division multiplexing

Abstract

A light source (200, 300, 400, 500, 600, 700) with a first mode and a second mode, wherein the light source comprises: at least one first laser array (210, 310, 410, 510, 610, 710), wherein: in the first mode, the first laser array emits optical signals of only one first wavelength within a first coarse wavelength multiplex (CWDM) passband, the first CWDM passband being a spectrum of wavelengths containing a first CWDM wavelength; and in the second mode, the first laser array emits optical signals of at least one first wavelength within the first CWDM passband and one second wavelength within the first CWDM passband.

Description

background The term wavelength division multiplexing (WDM) can refer to technologies that combine multiple optical signals of different wavelengths on a single optical fiber. These optical signals can be transmitted simultaneously over the fiber via separate wavelength transmission channels (to illustrate the concept, these wavelength transmission channels can be thought of as separate lanes on a highway for different colors of light, e.g., one lane / transmission channel for green light, one lane / transmission channel for blue light, etc.). There are two traditional approaches to WDM: coarse wavelength division multiplexing (CWDM) and dense wavelength division multiplexing (DWDM). CWDM uses a larger wavelength separation between transmission channels than DWDM. Certain CWDM technologies, for example, can separate transmission channels with a wavelength of approximately 20 nanometers (nm) in the electromagnetic spectrum. These wavelengths can be referred to as CWDM wavelengths. CWDM-4 is an industry standard that provides a common specification for optical interconnects (e.g., pluggable optical transceiver modules) used in various applications such as data centers. The CWDM-4 standard uses four CWDM wavelengths: approximately 1271, 1291, 1311, and 1331 nm. These four wavelengths can be referred to as CWDM-4 wavelengths. DWDM generally uses a higher number of wavelength transmission channels per optical fiber than CWDM. DWDM can accommodate these additional channels by packing them more densely than in CWDM. For example, DWDM wavelengths can be spaced approximately 0.4 nm or 0.8 nm apart (i.e., 25–50 times closer than in CWDM). US 2005 / 0220397A1 relates to an optical transmission system and an optical transmission method for transmitting wavelength-division multiplexed light using an optical fiber containing a variety of optical signals of different wavelengths. US 2016 / 006536A1 concerns a signal processing method and a bidirectional ring network system with coarse wavelength multiplexing (CWDM). US 2020 / 0 044 738 A1 concerns systems and procedures relating to bidirectional CWDM micro-optics. The present invention is defined by independent claims 1, 9 and 15. Embodiments are the subject of the respective dependent claims. Brief description of the drawings The present disclosure is described in detail in accordance with one or more different examples with reference to the following figures. The figures serve only for illustration and represent only typical or exemplary examples. Fig. 1 is an example diagram showing an architecture for coarse wavelength multiplexing according to various examples of the technology currently disclosed. Fig. 2 shows an exemplary wavelength light source corresponding to various examples of the technology presented herein. Fig. 3 shows another example of a waveband light source according to various examples of the technology currently disclosed. Fig. 4 shows another example of a waveband light source according to various examples of the technology currently disclosed. Fig. 5 shows another example of a waveband light source according to various examples of the technology currently disclosed.Fig. 6 shows another example of a waveband light source according to various examples of the currently disclosed technology. Fig. 7 shows another example of a waveband light source according to various examples of the currently disclosed technology. Fig. 8 shows an example of a waveband transmitter according to various examples of the currently disclosed technology. Fig. 9 shows another example of a waveband transmitter according to various examples of the currently disclosed technology. Fig. 10 shows another example of a waveband transmitter according to various examples of the currently disclosed technology. Fig. 11 shows another example of a waveband transmitter according to various examples of the currently disclosed technology. Fig. 12 shows another example of a waveband transmitter according to various examples of the currently disclosed technology.Figure 13 shows an example of a waveband receiver according to various examples of the technology presented herein. Figure 14 shows another example of a waveband receiver according to various examples of the technology disclosed herein. Figure 15 shows another example of a waveband receiver according to various examples of the technology disclosed herein. The figures are not exhaustive and do not limit the present revelation to the exact form that is revealed. Detailed description Optical links (e.g. devices that transmit signals from one place to another using light) are frequently used in high-performance computer networks because they can achieve high bandwidth over long distances with less energy expenditure compared to electrical links. Pluggable optical transceiver modules are components in optical interconnects that can contain a coherent light source (e.g., a laser), an optical data transmitter (an optical device capable of transferring data to an optical signal by modulating the optical signal), and an optical receiver (an optical device capable of sensing modulated optical signals) in the same package. Many of these pluggable optical transceiver modules are designed to operate using the CWDM-4 standard. Specifically, they are designed to generate, modulate, and sensing a single wavelength (within a specified tolerance) per CWDM-4 passband (as used here, a CWDM or CWDM-4 passband can refer to a spectrum of wavelengths that includes a CWDM / CWDM-4 wavelength capable of passing through an optical filter). In certain technology areas, such as…In data centers, pluggable optical CDWM-4 transceiver modules are ubiquitous. Using an industry-standard 100-Gigabit (G) serializer / deserializer (SERDES), these CDWM-4 modules can achieve data transmission rates of approximately 400 gigabits per second (Gbps) (i.e., 100 G x 4 wavelength transmission channels) per optical fiber. However, future networks are expected to require higher data transmission rates (e.g., 800 Gbit / s). Unfortunately, pluggable optical CWDM-4 transceiver modules (and other CWDM-4 devices) cannot achieve these higher rates with the SERDES 100G standard. One approach to increasing the transmission rate with the current 100G SERDES standard would be to increase the number of wavelength transmission channels per fiber (since the data rate per fiber is approximately proportional to the number of transmission channels per fiber). Accordingly, certain industries (e.g., telecommunications) have moved to dense wavelength division multiplexing (DWDM). As described above, DWDM can accommodate a large number of wavelength transmission channels per fiber by packing the transmission channels more densely than CWDM. However, switching to DWDM comes at a cost. Because the wavelength transmission channels for DWDM are more densely packed, the DWDM equipment (e.g., light sources / lasers) must be more precise and therefore more expensive. Furthermore, the channel spacing in DWDM can be too narrow in certain applications, such as data centers. This is because the spectrum of the optical signal broadens when data is transmitted over it. In applications like data centers, where large data packets (i.e., "large data payloads") are transmitted over optical signals, the broadened optical signals can overlap / interfere when transmitted over densely packed transmission channels, leading to crosstalk and higher bit error rates. Against this background, examples of the technology presented here enable gentle bandwidth scaling (i.e., a higher data rate) by using a waveband architecture built around the CWDM wavelengths. This waveband architecture adds additional wavelength transmission channels (as described above, additional transmission channels can be equated with higher data rates) while maintaining backward compatibility with existing CWDM / CWDM-4 technologies (e.g., pluggable CWDM-4 optical transceiver modules). In accordance with various examples, a CWDM waveband architecture can comprise one or more CWDM wavebands. A CWDM waveband can refer to two or more wavelengths within a CWDM passband. As described above, a CWDM passband can refer to a spectrum of wavelengths that includes a CWDM wavelength capable of passing through an optical filter. Accordingly, examples of the currently disclosed technology may include waveband devices (e.g., waveband light sources, waveband transmitters, waveband receivers, waveband transceivers, etc.) designed to operate with one or more CWDM wavebands while maintaining backward compatibility with existing CWDM-4 technologies. These waveband devices may consist of readily available components used in existing CWDM-4 technologies. For example, using the CWDM waveband concepts of this disclosure and components found in silicon photonics and III-V foundry design kits (e.g., distributed feedback CWDM-4 lasers, broadband fiber chip couplers, CWDM-4 optical filters, etc.), a "waveband light source" can be constructed to operate in two modes. In the first mode, the waveband light source can generate a single wavelength per CWDM-4 passband (consistent with existing CWDM-4 technologies). In the second mode, the waveband light source can generate multiple wavelengths per CWDM-4 passband (i.e., CWDM wavebands). To illustrate the concept, a waveband light source can be constructed using eight distributed feedback CWDM-4 lasers. Two of the lasers can be calibrated to generate light in a first CWDM-4 passband (the first CWDM-4 passband can have a spectrum of wavelengths between, for example, 1 / 30 ...These two lasers can be calibrated to produce different wavelengths of light within the first CWDM-4 passband (e.g., 1264.5 nm and 1277.5 nm, respectively). Similarly, two lasers can be calibrated to produce wavelengths of light in a second CWDM-4 passband (e.g., 1284.5 nm - 1297.5 nm); two lasers can be calibrated to produce wavelengths of light in a third CWDM-4 passband (e.g., 1304.5 nm - 1317.5 nm); and two lasers can be calibrated to produce wavelengths of light in a fourth CWDM-4 passband (e.g., 1324.5 nm - 1337.5 nm). When this waveband light source operates in the first mode, one laser per waveband / passband can be switched off.Accordingly, the waveband light source can seamlessly integrate with existing CWDM-4 technologies designed to operate with a single wavelength (within a specific tolerance) per CWDM-4 passband. When this waveband light source operates in its second mode, all eight lasers can be activated. Therefore, the waveband light source can generate eight wavelengths of light within the four CWDM-4 passbands, effectively doubling the number of wavelength transmission channels used by existing CWDM-4 technologies. When combined with a waveband transmitter and receiver designed to operate with these eight wavelengths, the waveband light source can achieve a data transmission rate of approximately 800 Gbps using 100 G SERDES (i.e., 100 G x 8 wavelength transmission channels). In certain examples, a waveband transmitter can be built using components from silicon photonics and III-V foundry process design kits (e.g., high-speed Mach-Zehnder or microring modulators, broadband fiber chip couplers, etc.). This waveband transmitter can (1) modulate a single wavelength per CWDM-4 passband (which would be compatible with existing CWDM-4 technologies), and (2) modulate two or more wavelengths per CWDM-4 passband. To illustrate the concept, a waveband transmitter can be built with eight optical modulators. Two of the optical modulators can be calibrated to modulate light within a first CWDM-4 passband (e.g., 1264.5 nm - 1277.5 nm). These two optical modulators can be calibrated to modulate different wavelengths of light within the first CWDM-4 passband (e.g., 1268.5 nm and 1273.5 nm, respectively).Similarly, two optical modulators can be calibrated to modulate light wavelengths in a second CWDM-4 passband (e.g., 1284.5 nm - 1297.5 nm); two optical modulators can be calibrated to modulate light wavelengths in a third CWDM-4 passband (e.g., 1304.5 nm - 1317.5 nm); and two optical modulators can be calibrated to modulate light wavelengths in a fourth CWDM-4 passband (e.g., 1324.5 nm - 1337.5 nm). Accordingly, this waveband transmitter can be operated seamlessly with existing CWDM-4 light sources and optical receivers (in which case four of the eight optical modulators would be used). The waveband transmitter can also be used in combination with waveband light sources and waveband receivers that operate with the CWDM-4 wavebands (here all eight optical modulators can be used).As described above, the combination of waveband devices using 100 G SERDES (i.e., 100 G x 8 wavelength transmission channels) can achieve a data transmission rate of approximately 800 Gbit / s. In some examples, a waveband receiver can be built using components from silicon photonics and III-V foundry process design kits (e.g., surveillance or high-speed waveguide photodetectors, broadband fiber chip couplers, etc.). This waveband receiver can detect (1) a single modulated wavelength per CWDM-4 passband (which would be compatible with existing CWDM-4 technologies) and (2) two or more modulated wavelengths per CWDM-4 passband. To illustrate the concept, a waveband receiver can be built with eight waveguide photodetectors. Two of the waveguide photodetectors can be calibrated to detect modulated light within a first CWDM-4 passband (e.g., 1264.5 nm - 1277.5 nm). These two waveguide photodetectors can be calibrated to detect different modulated wavelengths of light within the first CWDM-4 passband (e.g. 1268.5 nm or 1273.5 nm).Similarly, two waveguide photodetectors can be calibrated to detect modulated light wavelengths in a second CWDM-4 passband (e.g., 1284.5 nm - 1297.5 nm); two waveguide photodetectors can be calibrated to detect modulated light wavelengths in a third CWDM-4 passband (e.g., 1304.5 nm - 1317.5 nm); and two waveguide photodetectors can be calibrated to detect modulated light wavelengths in a fourth CWDM-4 passband (e.g., 1324.5 nm - 1337.5 nm). Accordingly, this waveband receiver can be operated seamlessly with existing CWDM-4 light sources and optical data transmitters (using four of the eight waveguide photodetectors). The waveband receiver can also be used in combination with waveband light sources and waveband transmitters that operate with the CWDM-4 wavebands (here all eight waveguide photodetectors can be used).As described above, the combination of waveband devices using the industry standard 100 G SERDES (i.e., 100 G x 8 wavelength transmission channels) can achieve a data transmission rate of approximately 800 Gbit / s. In various examples, a waveband light source, a waveband transmitter, and a waveband receiver can be integrated into a single physical structure, such as a pluggable waveband transceiver module and an electrical integrated circuit package. As described above, the pluggable waveband transceiver module and the electrical integrated circuit package can be constructed using components used to build existing pluggable optical CWDM-4 transceiver modules. Examples of the technology presented here offer numerous advantages over existing CWDM and DWDM technologies. For instance, waveband light sources, transmitters, and receivers can be constructed using readily available components already employed in existing CWDM-4 technologies. In many cases, these components are less expensive than those used in DWDM technologies. Another advantage of the technology presented here is that it provides options for gentle bandwidth scaling for technology sectors / industries that require a larger wavelength transmission channel spacing than DWDM allows. For example, the use of DWDM may not be practical for applications with large data volumes, such as data centers (since DWDM's sub-nanometer channel spacing may be too narrow for larger data volumes / wider optical signals).However, optical waveband devices can be built that operate, for example, with two wavelength transmission channels per CWDM-4 passband. These wavelength transmission channels can be spaced approximately 4–5 nm apart (in contrast to the 0.4 or 0.8 nm channel spacing in DWDM). Accordingly, data transmission rates can be doubled, while the wavelength transmission channel spacing remains sufficiently large for larger data payloads. A third advantage of the technology presented here is its backward compatibility with existing CWDM / CWDM-4 technologies. Backward compatibility is generally advantageous for new technologies, but it is particularly important in this field because CWDM-4 devices are so ubiquitous.Accordingly, optical waveband devices that enable data transmission rates of 800 Gbit / s (or more) while maintaining interoperability with legacy CWDM-4 devices may be highly desirable for technology sectors / industries that have relied heavily on CWDM-4 devices. Figure 1 is an example diagram showing a CWDM waveband architecture in accordance with various examples of the currently disclosed technology. As shown, the CWDM waveband architecture 100 consists of four wavebands. However, in other examples, a CWDM waveband architecture may also consist of one or more wavebands. As described above, a CWDM waveband can refer to two or more wavelengths within a CWDM passband. A CWDM passband can denote a spectrum of wavelengths that includes a CWDM wavelength capable of passing through an optical filter. CWDM wavelengths can refer to a range of wavelengths approximately 20 nm apart in the electromagnetic spectrum. In certain cases, a CWDM passband can be a spectrum of wavelengths that includes a CWDM-4 wavelength. A CWDM-4 wavelength can be one of four wavelengths located approximately 20 nm apart in the electromagnetic spectrum between about 1271 nm and 1331 nm (e.g., 1271 nm, 1291 nm, 1311 nm, 1331 nm). As shown, the CWDM waveband 110 consists of two wavelengths approximately 4.3 nm apart: wavelengths 110a and 110b. In other examples, the CWDM waveband 110 can consist of any number of wavelengths spaced apart by various lengths. However, in certain applications with large amounts of data, it can be advantageous to limit a waveband to 16 or fewer wavelengths. This is because when data is transmitted over an optical signal, the optical signal becomes "broader." Consequently, wider optical signals can begin to overlap when wavelength transmission channels are packed more densely, leading to crosstalk and bit errors in data transmission. The CWDM passband for CWDM wavelength 110 is centered on the first CWDM-4 wavelength of approximately 1271 nm and is approximately 13 nm wide. In other examples, a CWDM passband may have a different width (depending on the optical filter used) and does not necessarily have to be centered on a CWDM-4 wavelength. The CWDM wavebands 120, 130, and 140 also consist of two wavelengths. Similar to the CWDM passband for the CWDM waveband 110, the CWDM passbands for the CWDM wavebands 120, 130, and 140 are each centered on one of the CWDM-4 wavelengths. As described above, waveband architectures such as waveband architecture 110 increase the number of wavelength transmission channels for CWDM-based technologies. Specifically, optical devices designed to operate with waveband architecture 100 can utilize eight wavelength transmission channels (two wavelength transmission channels per CWDM waveband / passband). This is double the number of wavelength transmission channels used by existing CWDM-4 technologies. As described above, doubling the number of wavelength transmission channels can double the data transmission rate in the examples of this technology. To illustrate the concept, if each of the depicted CWDM wavebands encompassed three wavelengths instead of two, the data transmission rates could be three times higher than those of existing CWDM-4 technologies.Optical devices designed to operate with three wavelengths per CWDM waveband (as opposed to two) may require additional components / hardware (e.g., additional lasers, additional optical modulators, additional photodetectors, etc.), which can increase manufacturing and operating costs. Furthermore, the narrower channel spacing required to provide three wavelengths per CWDM waveband may not be preferred / optimal for certain applications. Fig. 2 shows an exemplary waveband light source corresponding to various examples of the currently disclosed technology. The waveband light source 200 comprises four laser arrays, a star coupler, eight input waveguides connecting the laser arrays to the star coupler, and eight output waveguides from the star coupler. Laser arrays 210, 212, 214, and 216 can be any laser array capable of generating two or more wavelengths of light within a CWDM passband. The term "laser array" refers to an arrangement of two or more lasers on a single physical structure, such as a silicon chip. As shown, each of the laser arrays comprises two lasers, but in other examples, the laser arrays can include additional lasers. In various examples, these laser arrays can be constructed using readily available distributed feedback CWDM-4 lasers found in silicon photonics and III-V foundry process design kits. Each laser in a laser array can generate coherent light of a specific wavelength within a CWDM passband. For example, laser 210a can generate a first wavelength of light within a first CWDM passband, and laser 210b can generate a second wavelength of light within the first CWDM passband (in practice, these wavelengths may shift slightly depending on the operating temperature, but the shifts generally occur in the same direction and by the same amount, ensuring that the wavelength transmission channel spacing is maintained). Accordingly, the two wavelengths generated by laser array 210 can be referred to as the first CWDM waveband. In the same / similar manner as lasers 210a and 210b, lasers 212a / 212b, 214a / 214b, and 216a / 216b can generate different wavelengths of coherent light within a second, third, and fourth CWDM passband, respectively.Accordingly, the wavelengths generated by laser arrays 212, 214, and 216 can be designated as the second, third, and fourth CWDM wavebands, respectively. In various embodiments, these four CWDM passbands / wavebands can be CWDM-4 passbands / wavebands. In summary, each laser array of the Waveband Light Source 200 can generate its own CWDM waveband. These four CWDM wavebands can encompass eight different wavelengths (i.e., eight wavelength transmission channels). Accordingly, the Waveband Light Source 200 can simultaneously generate eight optical signals that can be transmitted on these eight different wavelength transmission channels. These optical signals are represented as λ11, λ12, λ21, λ22, λ31, λ32, λ41, and λ42. The wavelengths of the optical signals λ11 and λ12 constitute the first waveband; the wavelengths of the optical signals λ21 and λ22 the second waveband; the wavelengths of the optical signals λ31 and λ32 the third waveband; and the wavelengths of the optical signals λ41 and λ42 the fourth waveband. These eight optical signals can be collectively referred to as the optical signals λ11-λ42 or as the “optical input signals”. In certain examples, the optical signals λ11-λ42 can be passed through optical filters (not shown). As described above, these optical filters can determine / define the spectrum of wavelengths contained in a CWDM passband for a given CWDM waveband. In other words, a CWDM passband for a given CWDM waveband can be defined as the spectrum of wavelengths that can be transmitted through an optical filter without attenuation. In various examples, the optical filters used in conjunction with the waveband light source 200 can be readily available optical filters used with existing CWDM-4 technologies. After passing through optical filters, the optical signals λ11-λ42 can be transmitted to the star coupler 220 via individual waveguides (i.e., input waveguides of the star coupler 220). These waveguides can be constructed using readily available optical elements (e.g., fiber-chip couplers, optical waveguides, etc.) included in silicon photonics foundry process design kits. The star coupler 220 can be any device (or a combination of devices) that receives a given input signal and splits it into multiple output signals. As described in more detail in conjunction with FIGS. 3-5, this star coupler 220 can be a single multimode interference device (MMI) or a combination of MMIs (e.g., cascaded MMIs). As used here, an MMI can refer to a microscale structure that splits or combines optical signals (and their respective powers) in a predictable manner. The star coupler 220 can split each of the optical input signals into eight optical output signals. For example, the star coupler 220 can split the optical signal λ11 into eight optical output signals: λ11(a), λ11(b), λ11(c), λ11(d), λ11(e), λ11(f), λ11(g), λ11(h) (these optical signals can be referred to as optical signals λ11(ah) or "the optical output signals of the optical input signal λ11"). As shown, each of the optical signals λ11(ah) can be transmitted to one of the eight output waveguides of the star coupler 220. By splitting the optical signal λ11 into eight optical output signals, the star coupler 220 divides the optical power of λ11 in eight ways. In other words, the power sharing ratio between the optical input signal λ11 and each of its associated output signals is 1:8. The optical signals λ12-λ42 can be divided in the same / similar way as the optical signal λ11. The Star Coupler 220 can not only split each of the optical input signals into eight optical output signals, but also combine (i.e., multiplex) optical signals on common output waveguides. For example, the Star Coupler 220 can combine the optical output signals λ11(a), λ12(a), λ21(a), λ22(a), λ31(a), λ32(a), λ41(a), and λ42(a) on the first output waveguide. Similarly, the Star Coupler 220 can combine the optical output signals λ11(b), λ12(b), λ21(b), λ22(b), λ31(b), λ32(b), λ41(b), and λ42(b) on the second output waveguide. Optical output signals λ11(c), λ12(c), λ21(c), λ22(c), λ31(c), λ32(c), λ41(c) and λ42(c) are routed to the third output waveguide, etc. As described above, each of these optical output signals can be a power-reduced version of one of the optical input signals.For example: the optical output signals λ11(a), λ11(b) and λ11(c) are reduced-power versions of the optical input signal λ11; the optical output signals λ12(a), λ12(b) and λ12(c) are reduced-power versions of the optical input signal λ12; the optical output signals λ21(a), λ21(b) and λ21(c) are reduced-power versions of the optical input signal λ21, etc. Accordingly, each of the eight waveguides exiting the star coupler 220 can receive / transmit a reduced-power version of each of the eight optical input signals. In summary, the Star Coupler 220 can (1) split each of the optical input signals into eight reduced-power optical output signals and (2) combine the reduced-power optical output signals corresponding to each of the optical input signals on common waveguides. Accordingly, each of the eight waveguides exiting the Star Coupler 220 can receive / transmit a single beam of light consisting of eight optical output signals. Each of these eight optical output signals can be a reduced-power version of one of the optical input signals (i.e., the optical signals λ12-λ42). As described in more detail below, each of these eight output waveguides can be connected to a separate bandpass transmitter. A specific bandpass transmitter can modulate the eight optical signals (with different wavelengths) that it receives.Thus, the aggregated output signals of these eight waveband transmitters can be 64 modulated optical signals (i.e., eight waveband transmitters x eight optical signals per waveband transmitter). As described above, the modulation of an optical signal can include the transmission of data into that signal. For example, the four laser arrays of the Waveband Light Source 200 can be used to simultaneously generate 64 optical signals capable of transmitting data. This 16:1 ratio between the number of generated optical signals and the number of laser arrays can be extremely attractive to certain customers. As described above, the Waveband Light Source 200 can operate in two modes. In the first mode, the Waveband Light Source 200 can be backward compatible with existing CWDM-4 technologies. Specifically, one laser per laser array can be switched off (or jammed, etc.) so that each laser array generates optical signals with only a single wavelength per CWDM-4 passband. Accordingly, in this first mode, the four laser arrays of the Waveband Light Source 200 can be used to simultaneously generate / transmit 32 optical signals suitable for data transmission (i.e., four optical input signals split across eight different output waveguides). In contrast, in the second mode, all lasers can be "switched on" (i.e., they can operate unhindered, etc.).Accordingly, the waveband light source 200 can be used to simultaneously generate / transmit 64 optical signals that can transmit data. Fig. 3 shows another example of a waveband light source in accordance with various examples of the currently disclosed technology. The waveband light source 300 comprises four laser arrays, an 8x8 multimode interference (MMI) device, eight input waveguides connecting the laser arrays to the 8x8 MMI, and eight output waveguides of the 8x8 MMI. Fig. 3 may be identical / similar to Fig. 2, except that the generic star coupler of Fig. 2 has been replaced by the 8x8 MMI 320. As described above, an MMI can refer to a microscale structure that splits or combines optical signals (and their power) in a predictable manner. Like the star coupler 220 in Fig. 2, the 8x8 MMI 320 has eight inputs and eight outputs (hence the prefix 8x8) and combines power-reduced versions of each of the optical input signals it receives (i.e., optical signals ξ11-ξ42) on eight different output waveguides. Accordingly, the waveband light source 300, like the waveband light source 200, can generate / transmit 64 optical signals suitable for data transmission. Fig. 4 shows another example of a waveband light source according to various examples of the technology disclosed herein. The waveband light source 400 comprises four laser arrays, four 2x2 MMIs, two 4x4 MMIs, and various waveguides connecting the aforementioned components. Here, the combination of the six MMIs forming the waveband light source 400 functions in the same / similar way as the star coupler 220 and the 8x8 MMI 320 of Figs. 2 and 3. Specifically, the combination of MMIs (which can be referred to as cascaded MMIs) combines power-reduced versions of each of the optical input signals generated by the laser arrays 410, 412, 414, and 416 onto eight different output waveguides emerging from the two 4x4 MMIs. In other words, each of the eight final output waveguides of the cascaded MMI combination can receive / transmit a single beam of light consisting of eight optical output signals, each of the eight optical output signals being a power-reduced version of one of the optical input signals ς11-ς42. Accordingly, the waveband light source 400, like the waveband light sources 200 and 300, can generate 64 optical signals that can transmit data. In various examples, the cascaded MMI architecture of Fig. 4 may be preferable to the single 8x8 MMI architecture of Fig. 3, as the cascaded MMI architecture of Fig. 4 may have a smaller / shorter physical profile. Fig. 5 shows another example of a waveband light source in accordance with various examples of the currently disclosed technology. The waveband light source 500 comprises four laser arrays, four microring resonators, a 4x4 MMI, and various waveguides. A microring resonator can refer to a closed waveguide that couples an input waveguide to an output waveguide. In this case, a specific microring resonator couples a waveguide carrying optical signals generated by a first laser in a laser array to a waveguide carrying optical signals generated by a second laser in the array. In other words, the microring resonators couple waveguides of a common waveband. Similar to the other components described above, these microring resonators can be fabricated / procured from readily available silicon photonics foundry process design kits or custom-designed based on a process design kit. In the example of the waveband light source 500, the four microring resonators can serve as drop filters for optical signals of specific wavelengths. For example, the microring resonator 520 can be tuned to drop optical signals of the wavelength generated by the laser 510a (e.g., the optical signal π11). The microring resonator 520 can also be tuned to allow optical signals of other wavelengths to pass through unimpeded. Accordingly, the microring resonator 520 can output the optical signal π11 to a waveguide carrying the optical signal π12, while the optical signal π12 can pass through unimpeded. These two optical signals (which, as described above, can comprise a first CWDM waveband) can then be transmitted to the 4x4 MMI 530 via a common waveguide. The microresonators 522, 524, and 526 can be tuned in the same / similar way. Accordingly, the 4x4 MMI 530 can have four input waveguides.As described above, each of the waveguides entering 4x4 MMI 530 can transmit optical signals of a common CWDM waveband. The 4x4 MMI 530 has four input waveguides and four output waveguides (hence the prefix 4x4). Accordingly, the 4x4 MMI 530 operates somewhat differently from the star coupler 220, the 8x8 MMI 320, and the cascaded MMI combination of Fig. 4. In particular, the 4x4 MMI 530 combines power-reduced versions of the optical input signals generated by the laser arrays 510, 512, 514, and 516 on four different output waveguides. In other words, each of the optical input signals π11–π42 is split into only four output signals (whereas in Figs. 2–4, each input signal was split into eight output signals). Because each input signal is split into only four output signals, the power split ratio between input and output signals is only 1:4. This lower power division ratio may be preferred in applications that require higher power optical signals in the detection stage.Unlike the Waveband Light Sources 200, 300, and 400, which can generate / transmit 64 optical signals, the Waveband Light Sources 500 can only generate 32 optical signals suitable for data transmission. Accordingly, light sources like the Waveband Light Source 500 may compromise on data transmission density to achieve higher-power optical signals. Fig. 6 shows another example of a waveband light source in accordance with various examples of the currently disclosed technology. The waveband light source 600 comprises four laser arrays, two multiplexers (MUXs), a microring interleaver MUX, and various waveguides connecting the aforementioned components. As shown, the laser array 610 can generate optical signals of a first waveband. In particular, laser 610a can generate optical signals with a first wavelength of the first waveband (e.g., optical signal ϕ11), and laser 610b can generate optical signals with a second wavelength of the first waveband (e.g., optical signal ϕ12). Optical signals of the first wavelength of the first waveband (e.g., optical signal ϕ11) can be routed to MUX 620, and optical signals of the second wavelength of the first waveband (e.g., optical signal ϕ12) to MUX 622. Similarly, optical signals of the first wavelength of the second waveband (e.g., optical signal ϕ21) can be routed to MUX 620, and optical signals of the second wavelength of the second waveband (e.g., optical signal ϕ22) to MUX 622. Similarly, optical signals of the first wavelength of the third waveband (e.g., optical signal ϕ21) can be routed to MUX 620.Optical signals ϕ31 are routed to MUX 620, and optical signals of the second wavelength of the third waveband (e.g., optical signal ϕ32) are routed to MUX 622. Similarly, optical signals of the first wavelength of the fourth waveband (e.g., optical signal ϕ41) can be routed to MUX 620, and optical signals of the second wavelength of the second waveband (e.g., optical signal ϕ42) can be routed to MUX 622. In summary, MUX 620 can receive optical signals of the first wavelength of the CWDM wavebands (which can be referred to as "odd optical signals"), and MUX 622 can receive optical signals of the second wavelength of the CWDM wavebands (which can be referred to as "even optical signals"). As described above, a multiplexer (or MUX) can refer to an optical device that combines multiple optical signals of different wavelengths on shared optical fibers / waveguides (in other words, a MUX can combine optical signals of different wavelengths into a common beam of light that can be transmitted along a single waveguide). Accordingly, the MUXs 620 and 622 can combine the optical signals of different wavelengths that they receive on shared waveguides. Specifically, the MUX 620 can combine odd-numbered optical signals (e.g., the optical signals ϕ11, ϕ21, ϕ31, ϕ41) on a first shared waveguide. The MUX 622 can combine even-numbered optical signals (e.g., the optical signals ϕ12, ϕ22, ϕ32, ϕ42) on a second shared waveguide.Since neither of the optical signals is shared between MUXs 620 and 622 in this case, the optical signals output by the MUXs are not reduced in power. In other words, the power sharing ratio is 1:1 for MUXs 620 and 622. The MUXs 620 and 622 can be different types of MUXs. In certain embodiments, the MUXs 620 and 622 can be grid filter MUXs or array waveguide grid (AWG) MUXs, which can be constructed / procured / designed from readily available silicon photonics foundry process design kits. The waveguides emanating from MUXs 620 and 622 each lead to a microring interleaver MUX 630. A microring interleaver MUX can be an optical device that combines even multiplexed optical signals with odd multiplexed optical signals on a common fiber / waveguide. Similar to the microring resonators in Fig. 5, the microring interleaver MUX 630 can serve as a drop filter for optical signals of specific wavelengths. In particular, the microring interleaver MUX 630 can be tuned to drop odd optical signals (e.g., optical signals ϕ11, ϕ21, ϕ31, ϕ41) onto the waveguide carrying even optical signals, while allowing even optical signals (e.g., optical signals ϕ12, ϕ22, ϕ32, ϕ42) to pass through unimpeded. In this way, the MUX 630 microring interleaver can combine odd and even optical signals (e.g., optical signals ϕ11-ϕ42) on a single output waveguide. In certain examples, the Microring Interleaver MUX 630 can have a periodic free spectral range (FSR). This FSR allows the Microring Interleaver MUX 630 to "drop" optical signals with wavelengths spaced a certain distance apart. For example, the lasers 610a, 612a, 614a, and 616a can be calibrated to produce "odd" wavelengths of light spaced approximately 20 nm apart. Accordingly, the FSR of the Microring Interleaver MUX 630 can be tuned to "drop" optical signals with these odd, periodically spaced wavelengths. In certain embodiments, the interleaver MUX can be constructed from one or more microrings, Mach-Zehnder interferometers, etc. Fig. 7 shows another example of a waveband light source in accordance with various examples of the currently disclosed technology. The waveband light source 700 can be considered a general waveband light source from which the waveband light sources 200-600 can be derived. The waveband light source 700 comprises at least one first laser array, laser array 710, although the waveband light source 700 can comprise any number of laser arrays. For example, the waveband light source 700 can also comprise a second laser array (e.g., laser array 712), a third laser array (e.g., laser array 714), and a fourth laser array (e.g., laser array 716). The LaserArray 710 can be any laser array that emits optical signals of at least one first and one second wavelength within a first CWDM passband. As described above, the first CWDM passband can be a spectrum of wavelengths that includes a CWDM wavelength capable of passing through an optical filter. In certain examples, the first CWDM passband can include a CWDM-4 wavelength. In some of these examples, the first CWDM passband can contain the first CWDM-4 wavelength (i.e., approximately 1271 nm). The Laser Array 710 can be an arrangement of two or more lasers on a single physical structure, such as a silicon or InP chip. Accordingly, a first laser of the Laser Array 710 (e.g., Laser 710a) can emit optical signals of the first wavelength within the first CWDM passband. A second laser of the Laser Array 710 (e.g., Laser 710b) can emit optical signals of the second wavelength within the first CWDM passband. In certain examples, the Laser Array 710 can include additional lasers that emit optical signals of a third wavelength within the first CWDM passband, a fourth wavelength within the first CWDM passband, and so on. In various examples, the Laser Array 710 can be constructed using readily available distributed feedback CWDM-4 lasers included in silicon photonics foundry process design kits. As described above, the Waveband Light Source 700 can operate in two modes. In the first mode, the Laser Array 710 can emit optical signals of only the first wavelength within the first CWDM passband (e.g., the Laser 710b can be switched off or blocked, etc.). Accordingly, in this first mode, the Waveband Light Source 700 can operate with existing CWDM technologies that only use a single wavelength per CWDM passband. In the second mode, the Laser Array 710 can emit optical signals of at least the first and second wavelengths within the first CWDM passband. In this second mode, the Waveband Light Source 700 can work in conjunction with other Waveband devices to increase the number of wavelength transmission channels for CWDM technologies. In various examples, the waveband light source 700 can include a star coupler 720. As described above, the star coupler 720 can be any device (or a combination of devices) that splits a given input signal into multiple output signals. Accordingly, the star coupler 720 can include any device or a combination of the following: one or more multimode interference (MMI) devices; one or more optical multiplexers (e.g., microring resonators / drop filters, grating filter multiplexers, microring interleaver multiplexers, array waveguide gratings, echelle gratings, etc.); and one or more optical demultiplexers (e.g., microring resonators / drop filters, grating filter demultiplexers, microring interleaver demultiplexers, array waveguide gratings, echelle gratings, etc.). Accordingly, the star coupler 720 can receive a first optical signal (FS) from a first input waveguide when the waveband light source 700 is operating in second mode. The FS can have the first wavelength within the first CWDM passband. Similarly, the star coupler 720 can receive a second optical signal (SS) from a second input waveguide. The SS can have the second wavelength within the first CWDM passband. The star coupler 720 can receive the FS and the SS in one of the ways described in conjunction with Figures 2-6. The star coupler 720 can also receive the optical signals in other ways. Upon receiving FS and SS, the Star Coupler 720 can combine the versions of FS and SS on a common waveguide. In other words, the Star Coupler 720 can combine a first version of FS (i.e., FS1) with a first version of SS (i.e., SS1) on a first output waveguide. In some cases, FS1 may be identical to FS. In others, FS1 may be a reduced-power version of FS. SS1 may be of the same or a similar power level to SS. In certain embodiments, the star coupler 720 can combine first versions of additional optical signals with the first output waveguide. For example, the laser array 712 can emit optical signals with a first and a second wavelength within a second CWDM passband (i.e., a second CWDM waveband). Accordingly, the star coupler 720 can combine all of the following elements on the first output waveguide: FS1 (that is, the first wavelength within the first CWDM passband); SS1 (that is, the second wavelength within the first CWDM passband); a first version of a third optical signal (that can be the first wavelength within the second CWDM passband); and a first version of a fourth optical signal (that can be the second wavelength within the second CWDM passband), and so on. The 720 star coupler can combine these optical signals in any of the ways described in conjunction with Figures 2-6. The 720 star coupler can also combine these optical signals in other ways. In various scenarios, the Star Coupler 720 can split power-reduced versions of FS (as well as other optical signals) to two or more output waveguides. For example, the Star Coupler 720 can split a first power-reduced version of FS (e.g., FS1) to the first output waveguide and a second power-reduced version of FS (e.g., FS2) to a second output waveguide. In some scenarios, the first power-reduced version of the first optical signal (e.g., FS1) and the second power-reduced version of the first optical signal (e.g., FS2) can be identical. In the same / similar manner, the 720 star coupler can split power-reduced versions of other received optical signals to the first and second output waveguides. In certain examples, the 720 star coupler can split power-reduced versions of the received optical signals to additional output waveguides (e.g., a third output waveguide, a fourth output waveguide, etc.). The 720 star coupler can split the power-reduced versions of the input / received optical signals in any of the ways described in conjunction with Figures 2-6. The 720 star coupler can also split the optical signals in other ways. In certain examples, the Waveband Light Source 700 (as well as the Waveband Light Sources 200-600) can include one or more optical modulators calibrated / tuned to modulate optical signals of the emitted wavelengths. As described in more detail in conjunction with Figures 8-12, an optical modulator can be an optical device that transfers data to an optical signal by modulating the optical signal. An optical modulator can be calibrated to modulate optical signals of a specific wavelength. For example, a first optical modulator can be calibrated / tuned to modulate optical signals of the first wavelength within the first CWDM passband. Similarly, a second optical modulator can be calibrated / tuned to modulate optical signals of the second wavelength within the first CWDM passband. The optical modulators incorporated into the Waveband Light Source 700 can be of various types. For example, if the Waveband Light Source 700 emits optical signals encompassing CWDM-4 wavebands, it can utilize readily available direct modulated lasers, electroabsorption modulated lasers, and other optical modulators used with existing CWDM-4 technologies. In some cases, the optical modulators might be microring modulators. In other cases, they might be Mach-Zehnder modulators. In certain examples, the waveband light source 700 (or more precisely, its lasers and optical modulators) can modulate optical signals before they enter the star coupler 720 or after they leave the star coupler 720. In other examples, optical modulators can be integrated into the star coupler 720. In still other examples, the optical signals generated by the waveband light sources 700 can be modulated outside the waveband light source 700. Accordingly, Figures 8-12 describe examples of waveband transmitters that can externally modulate the optical signals generated by the waveband light sources 200-700. Fig. 8 shows an example of a waveband transmitter according to various examples of the technology disclosed herein. The waveband transmitter 800 comprises a waveband demultiplexer (DEMUX), four wavelength DEMUXs, eight optical modulators, four wavelength multiplexers (MUXs), a waveband MUX, and various waveguides connecting the said optical components. In general, a waveband transmitter can receive optical signals from one or more CWDM wavebands on a common waveguide. These wavebands can consist of two or more wavelengths. Here, the 800 waveband transmitter can receive eight optical signals with eight different wavelengths on a single input waveguide (i.e., optical signals θ11, θ12, θ21, θ22, θ31, θ32, θ41, θ42). These eight different wavelengths can be comprised of four CWDM wavebands, each with two wavelengths. For example, the wavelengths of optical signals θ11 and θ12 can comprise a first CWDM waveband; the wavelengths of optical signals θ21 and θ22 can comprise a second CWDM waveband; the wavelengths of optical signals θ31 and θ32 can comprise a third CWDM waveband; and the wavelengths of optical signals θ41 and θ42 can comprise a fourth CWDM waveband. In some examples, these CWDM wavebands can be CWMD-4 wavebands. In other examples, the waveband transmitter can receive 800 optical signals with a different number of CWDM wavebands (e.g.,optical signals with two wavebands, three wavebands, five wavebands, etc.). Similarly, the CWDM wavebands can consist of additional wavelengths (e.g., three wavelengths per CWDM waveband, four wavelengths per CWDM waveband, etc.). In the specific example shown in Fig. 8, the waveband transmitter 800 receives optical signals from four CWDM wavebands, each CWDM waveband consisting of two wavelengths. In other words, the waveband transmitter 800 can receive eight optical signals on a single input waveguide. Accordingly, the waveband transmitter 800 can be operated with any of the waveband light sources described in connection with Figs. 2-7. As already mentioned, each of these waveband light sources could generate eight optical signals (consisting of four CWDM wavebands, each with two wavelengths) on at least one common output waveguide. As shown, the optical signals θ11-θ42 are received by the waveband transmitter 800 and transmitted to the waveband DEMUX 810. As the counterpart to an optical MUX, an optical DEMUX (e.g., the Waveband DEMUX 810) can split a multiplexed light beam into two or more light beams based on wavelength / waveband. In other words, an optical DEMUX can receive multiple optical signals with different wavelengths / wavebands traveling through a common waveguide and split the optical signals onto separate waveguides according to wavelength / waveband. The term "waveband demultiplexer," as used here (e.g., Waveband DEMUX 810), can refer to an optical demultiplexer that splits an input light beam according to wavelength. For example, a waveband demultiplexer can split an input light beam consisting of optical signals from multiple wavebands into separate light beams consisting of optical signals from each individual waveband.In some examples, a wavelength demultiplexer may refer to an optical demultiplexer that splits a light beam according to wavelength. For instance, a wavelength demultiplexer can split a light beam consisting of optical signals of multiple wavelengths into separate light beams consisting of optical signals of a single wavelength. Waveband and wavelength demultiplexers can include, among others, grating filter demultiplexers, echelle gratings, and array waveguide gratings, which can be constructed or sourced from readily available silicon photonics foundry process design kits. Here, the waveband DEMUX 810 can split the optical signals θ11-θ42 into CWDM wavebands on four separate waveguides (i.e., the waveband DEMUX 810 can split the received single light beam into four CWDM wavebands). Specifically, the waveband DEMUX 810 can split the optical signals θ11 and θ12 onto a first waveguide; the optical signals θ21 and θ22 onto a second waveguide; the optical signals θ31 and θ32 onto a third waveguide; and the optical signals θ41 and θ42 onto a fourth output waveguide. After being divided into wavebands, the optical signals θ11-θ42 can be further divided into individual wavelengths by wavelength demuxes 820-826. Accordingly, each of the optical signals θ11-θ42 can be distributed to separate waveguides based on its respective wavelength. These waveguides can then transmit the optical signals to the optical modulators 830-837. As described above, an optical modulator can be an optical device that transmits data to an optical signal by modulating the optical signal. Each optical modulator can be calibrated to modulate optical signals of a specific wavelength. For example, optical modulator 830 can be calibrated to modulate optical signals with the wavelength of optical signal θ11, optical modulator 831 can be calibrated to modulate optical signals with the wavelength of optical signal θ12, and so on. Accordingly, optical modulators 830–837 can each assign separate data packets to optical signals θ11–θ42. These modulated optical signals can be represented as optical signals θ'11, θ'12, θ'21, θ'22, θ'31, θ'32, θ'41, and θ'42. The optical modulators 830–837 can be various types of optical modulators. For example, if the optical signals comprise θ11–θ42 CWDM-4 wavebands, the optical modulators 830–837 can be readily available optical modulators used with existing CWDM-4 technology. In some examples, the optical modulators 830–837 may be microring modulators. In other examples, they may be Mach-Zehnder or electroabsorption modulators, but this is not a limitation. The modulated optical signals θ'11- θ'42 can be directed to the wavelength MUXs 840 - 846. As described above, MUXs can refer to optical devices that combine optical signals of different wavelengths on shared waveguides. The term "wavelength multiplexer," as used here, can refer to an optical multiplexer that combines two or more beams of light according to wavelength. In other words, a wavelength multiplexer can combine a first beam of light, consisting of a first optical signal of a first wavelength, with a second beam of light, consisting of a second optical signal of a second wavelength, into a single beam of light. The term waveband multiplexer, as used here, can refer to an optical multiplexer that combines two or more beams of light according to wavelength.For example, a waveband multiplexer can combine a first light beam, consisting of optical signals from a first CWDM waveband, with a second light beam, consisting of optical signals from a second CWDM waveband, into a single light beam. Wavelength and waveband multiplexers can be, among other things, grating filter, microring, and array waveguide grating multiplexers, which can be constructed / procured from readily available silicon photonics foundry process design kits. Accordingly, wavelength multiplexers 840–846 can combine the modulated optical signals they receive (with different wavelengths) on a common waveguide. Specifically, wavelength multiplexer 840 can combine modulated optical signals θ'11 and θ'12 on a first waveguide; wavelength multiplexer 842 can combine modulated optical signals θ'21 and θ'22 on a second waveguide; wavelength multiplexer 844 can combine modulated optical signals θ'31 and θ'32 on a third waveguide; and wavelength multiplexer 846 can combine modulated optical signals θ'41 and θ'42 on a fourth waveguide. Each of these four waveguides can transmit modulated optical signals of a common waveband to waveband multiplexer 850. The Waveband MUX 850 can combine the modulated optical signals of the four wavebands onto a single output waveguide. As described below, these modulated optical signals can be passed to a waveband receiver, which detects the modulated optical signals. This can be considered equivalent to "reading / extracting" the data superimposed on the modulated optical signals. Like the waveband light sources described in conjunction with Fig. 2-6, the Waveband Transmitter 800 can also operate with existing CWDM / CWDM-4 technologies. For example, the Waveband Transmitter 800 can operate with existing CWDM-4 technologies by tuning either the even optical modulators (i.e., optical modulators 830, 832, 834, and 836) or the odd optical modulators (i.e., optical modulators 831, 833, 835, and 837) to modulate optical signals with the CWDM-4 wavelengths. Similarly, the DEMUXs and MUXs of the Waveband Transmitter 800 can be calibrated to split or combine optical signals of the CWDM-4 wavelengths. Accordingly, the Waveband Transmitter 800 can be operated with both existing CWDM-4 technologies and upscaled technologies that utilize the CWDM wavelengths of the present disclosure. Fig. 9 shows another example of a waveband transmitter according to various examples of the technology disclosed herein. The waveband transmitter 900 comprises a waveband demultiplexer (DEMUX), eight microring modulators, eight monitoring photodetectors, a waveband multiplexer (MUX), and various waveguides connecting the aforementioned optical components. Similar to the Waveband Transmitter 800, the Waveband Transmitter 900 can receive eight optical signals with eight different wavelengths on a single input waveguide (i.e., optical signals B11, B12, B21, B22, B31, B32, B41, B42). These eight different wavelengths can be comprised of four CWDM wavebands, each with two wavelengths. For example, the wavelengths of optical signals B11 and B12 can comprise a first CWDM waveband; the wavelengths of optical signals B21 and B22 can comprise a second CWDM waveband; the wavelengths of optical signals B31 and B32 can comprise a third CWDM waveband; and the wavelengths of optical signals B41 and B42 can comprise a fourth CWDM waveband. These CWDM wavebands can be CWMD-4 wavebands. In other examples, the waveband transmitter can receive 900 optical signals with a different number of CWDM wavebands.Similarly, CWDM wavebands can consist of additional wavelengths (e.g., three wavelengths per CWDM waveband, four wavelengths per CWDM waveband, etc.). Generally, a waveband transmitter (e.g., the Waveband Transmitter 900) can receive optical signals from one or more CWDM wavebands on a common waveguide. These wavebands can be composed of two or more wavelengths. As shown, optical signals B11-B42 can be received from the waveband transmitter 900 and forwarded to the waveband DEMUX 910 (the waveband DEMUX 910 can be the same / similar to the waveband DEMUX 810). Accordingly, the waveband DEMUX 910 can split the optical signals B11-B42 according to the waveband in the same / similar way as described in conjunction with Fig. 8 (i.e., the waveband DEMUX 910 can split the received single light beam into four CWDM wavebands). In particular, the waveband DEMUX 910 can split the optical signals B11 and B12 onto a first waveguide; the optical signals B21 and B22 onto a second waveguide; and the optical signals B31 and B32 onto a third waveguide. and the optical signals B41 and B42 onto a fourth waveguide. The microring modulators 930a, 930b, 932a, 932b, 934a, 934b, 936a and 936b can be coupled to these four waveguides. In particular, the microring modulators 930a and 930b can be coupled to the first waveguide, the microring modulators 932a and 932b to the second waveguide, the microring modulators 934a and 934b to the third waveguide, and the microring modulators 936a and 936b to the fourth waveguide. A microring modulator can be an optical device that transmits data to an optical signal by modulating the optical signal. Each microring modulator can be tuned to modulate optical signals of a specific wavelength while allowing optical signals of other wavelengths to pass through unimpeded. For example, microring modulator 930a can be tuned to modulate optical signals of the wavelength of optical signal B11 while allowing optical signals of other wavelengths (e.g., optical signal B12) to pass through unimpeded. Similarly, microring modulator 930b can be tuned to modulate optical signals of the wavelength of optical signal B12 while allowing optical signals of other wavelengths (e.g., optical signal B11) to pass through unimpeded. The other microring modulators shown can be tuned in the same / similar way.Accordingly, these eight microring modulators can modulate optical signals B11-B42. These modulated optical signals can be represented as modulated optical signals B'11-B'42. In various embodiments, these microring modulators can be sourced from readily available silicon photonics foundry process design kits or custom-designed. The surveillance photodetectors 920a, 920b, 922a, 922b, 924a, 924b, 926a and 926b can be coupled with the microring modulators 930a, 930b, 932a, 932b, 934a, 934b, 936a and 936b, respectively. A surveillance photodetector can refer to an optical device capable of detecting modulated or unmodulated optical signals of a specific wavelength (or wavelengths). For example, the monitoring photodetector 920a can be tuned to detect optical signals of the wavelength of the modulated optical signal Δ11, the photodetector 920b can be tuned to detect modulated optical signals of the wavelength of the modulated optical signal Δ12, the photodetector 922a can be tuned to detect modulated optical signals of the wavelength of the optical signal Δ21, etc.In this case, the monitoring photodetectors can be integrated into the 900 waveband transmitter to monitor and adjust the bias point of the modulators. These monitoring photodetectors, available in various configurations, can be sourced from readily available silicon photonics foundry process design kits or custom-designed. After modulation, the optical signals Δ'11-Δ'42 can be routed to the waveband MUX 940 (which may be identical or similar to the waveband MUX 850). In the same or similar manner as described in conjunction with Fig. 8, the waveband MUX 940 can combine the modulated optical signals of the four wavebands onto a single output waveguide. As described below, these modulated optical signals can be routed to a waveband receiver, which detects the modulated optical signals. This can correspond to "reading / extracting" the data superimposed on the modulated optical signals. Similar to the Waveband Transmitter 800, the Waveband Transmitter 900 can also be operated with existing CWDM / CWDM-4 technologies. For example, the Waveband Transmitter 900 can be combined with existing CWDM-4 technologies by tuning either the optical ring modulators "a" (i.e., the optical ring modulators 930a, 932a, 934a, and 936a) or the optical modulators "b" (i.e., the optical ring modulators 930b, 932b, 934b, and 936b) to modulate optical signals at the CWDM-4 wavelengths. Similarly, the Waveband DEMUX and Waveband MUX of the Waveband Transmitter 900 can be calibrated to split or combine optical signals at the CWDM-4 wavelengths, respectively. Accordingly, the Waveband Transmitter 900 can be operated with both existing CWDM-4 technologies and upscaled technologies that utilize the CWDM wavebands of the present disclosure. Fig. 10 shows another example of a waveband transmitter according to various examples of the currently disclosed technology. Similar to the Waveband Transmitters 800 and 900, the Waveband Transmitter 1000 can receive eight optical signals with eight different wavelengths on a single input waveguide (i.e., optical signals β11, β12, β21, β22, β31, β32, β41, β42). These eight different wavelengths can comprise four CWDM wavebands, each with two wavelengths. For example, the wavelengths of optical signals β11 and β12 can comprise a first CWDM waveband; the wavelengths of optical signals β21 and β22 can comprise a second CWDM waveband; the wavelengths of optical signals β31 and β32 can comprise a third CWDM waveband; and the wavelengths of optical signals β41 and β42 can comprise a fourth CWDM waveband. In some examples, these CWDM wavebands can be CWMD-4 wavebands. In other examples, the waveband transmitter can receive 1000 optical signals from a different number of CWDM wavebands.Similarly, CWDM wavebands can consist of additional wavelengths (e.g., three wavelengths per CWDM waveband, four wavelengths per CWDM waveband, etc.). Generally, a waveband transmitter (e.g., the Waveband Transmitter 1000) can receive optical signals from one or more CWDM wavebands on a common waveguide. These wavebands can be composed of two or more wavelengths. As described above, the first wavelengths of each CWDM waveband (i.e., the wavelengths of the optical signals β11, β21, β31, and β41) can be referred to as "odd wavelengths." The second wavelengths of each CWDM waveband (i.e., the wavelengths of the optical signals β12, β22, β32, and β42) can be referred to as "even wavelengths." As shown, optical signals β11-β42 can be received from the waveband transmitter 1000 and routed to the interleaver DEMUX 1010. An interleaver DEMUX can refer to an optical device that splits multiplexed optical signals with odd and even wavelengths onto separate waveguides. Accordingly, the interleaver DEMUX 1010 can split optical signals with odd wavelengths (e.g., optical signals β11, β21, β31, and β41) onto a first waveguide and optical signals with even wavelengths (e.g., optical signals β12, β22, β32, and β42) onto a second waveguide. The even and odd optical signals can be routed to the DEMUXs 1020 and 1022, respectively, via their respective waveguides. The DEMUXs 1020 and 1022 can then distribute the received optical signals to separate waveguides according to wavelength. Specifically, the DEMUX 1020 can distribute odd-wavelength optical signals (e.g., optical signals β11, β21, β31, and β41) to four separate waveguides according to wavelength. For example, the DEMUX 1020 can distribute the β11 optical signal to a first waveguide; the β21 optical signal to a second waveguide; the β31 optical signal to a third waveguide; and the β41 optical signal to a fourth waveguide. DEMUX 1022 can split optical signals with even wavelengths (e.g. optical signals β12, β22, β32 and β42) in the same / similar way.In various embodiments, the DEMUXs 1020 and 1022 can be, among other things, grid filters, microrings, array waveguide grids and echelle grid DEMUXs, which can be constructed / procured from readily available silicon photonics foundry process design kits. Once an optical signal of a specific wavelength is on its own waveguide, it can be directed to an optical modulator calibrated to modulate optical signals of that specific wavelength. For example, the optical signal β11 can be directed to the optical modulator 1031, which can be calibrated to modulate optical signals of the wavelength of the optical signal β11. The other optical signals can be modulated in the same / similar way. As described above, the optical modulators 1030-1037 can be various types of optical modulators. For example, if the optical signals comprise β11-β42CWDM-4 wavebands, the optical modulators 1030-1037 can be readily available optical modulators used with existing CWDM-4 technologies. In some examples, the optical modulators 1030-1037 can be microring modulators. In other examples, they can be Mach-Zehnder modulators. The odd-numbered modulated optical signals (which can be represented as β'11, β'21, β'31, and β'41) can be routed to MUX 1040, and the even-numbered modulated optical signals (which can be represented as β'12, β'22, β'32, and β'42) can be routed to MUX 1042. In the same / similar manner as described in the previous figures, MUX 1040 can combine the odd-numbered modulated optical signals on one waveguide, and MUX 1042 can combine the even-numbered modulated optical signals on another waveguide. These two waveguides can then route the modulated optical signals to the interleaver MUX 1050. An interleaver MUX can refer to an optical device that combines odd-wavelength optical signals with even-wavelength optical signals on a common waveguide. Accordingly, the Interleaver MUX 1050 can combine modulated odd-wavelength optical signals (e.g., optical signals β'11, β'21, β'31, and β'41) with modulated even-wavelength optical signals (e.g., optical signals β'12, β'22, β'32, and β'42) on a common output waveguide. As described below, these modulated optical signals can be passed to a waveband receiver, which detects the modulated optical signals. This can be considered equivalent to "reading / extracting" the data transferred onto the modulated optical signals. Similar to the Waveband Transmitters 800 and 900, the Waveband Transmitter 1000 can also be operated with existing CWDM / CWDM-4 technologies. For example, the Waveband Transmitter 1000 can be combined with existing CWDM-4 technologies by tuning either the odd-numbered optical modulators (i.e., optical modulators 1031, 1033, 1035, 1037) or the even-numbered optical modulators (i.e., optical modulators 1030, 1032, 1034, 1036) to modulate optical signals at the CWDM-4 wavelengths. Similarly, the DEMUXs and MUXs of the Waveband Transmitter 1000 can be calibrated to split or combine optical signals at the CWDM-4 wavelengths. Accordingly, the waveband transmitter 1000 can be operated with both existing CWDM-4 technologies and upscaled technologies that utilize the CWDM wavelengths of the present disclosure. Fig. 11 shows another example of a waveband transmitter according to various examples of the technology presented here. The waveband transmitter 1100 comprises a micro-ring interleaver DEMUX, two additional DEMUXs downstream of the micro-ring interleaver DEMUX, eight Mach-Zehnder modulators, two MUXs, a micro-ring interleaver MUX, and various waveguides connecting the aforementioned optical components. Similar to the 800-1000 waveband transmitters, the 1100 waveband transmitter can receive eight optical signals with eight different wavelengths on a single input waveguide (i.e., optical signals κ11, κ12, κ21, κ22, κ31, κ32, κ41, κ42). These eight different wavelengths can comprise four CWDM wavebands, each with two wavelengths. For example, the wavelengths of optical signals κ11 and κ12 can comprise a first CWDM waveband; the wavelengths of optical signals κ21 and κ22 can comprise a second CWDM waveband; the wavelengths of optical signals κ31 and κ32 can comprise a third CWDM waveband; and the wavelengths of optical signals κ41 and κ42 can comprise a fourth CWDM waveband. In some examples, these CWDM wavebands may be CWDM-4 wavebands. In other examples, the waveband transmitter can receive 1100 optical signals with a different number of CWDM wavebands.Similarly, CWDM wavebands can consist of additional wavelengths (e.g., three wavelengths per CWDM waveband, four wavelengths per CWDM waveband, etc.). Generally, a waveband transmitter (e.g., the Waveband Transmitter 1100) can receive optical signals from one or more CWDM wavebands on a common waveguide. These wavebands can consist of two or more wavelengths. As described above, the first wavelengths of each CWDM waveband (i.e., the wavelengths of the optical signals κ11, κ21, κ31, and κ41) can be referred to as "odd wavelengths." The second wavelengths of each CWDM waveband (i.e., the wavelengths of the optical signals κ12, κ22, κ32, and κ42) can be referred to as "even wavelengths." As shown, the optical signals κ11-κ42 can be received from the waveband transmitter 1100 and forwarded to the micro-ring interleaver DEMUX 1110. An interleaver DEMUX can refer to an optical device that splits multiplexed optical signals with odd and even wavelengths onto separate waveguides. The micro-ring interleaver DEMUX 1110 can serve as a drop filter for optical signals of specific wavelengths. In particular, the micro-ring interleaver DEMUX 1110 can be tuned to drop odd optical signals (e.g., optical signals κ11, κ21, κ31, κ41) onto the waveguide that carries the odd optical signals to DEMUX 1120, while allowing even optical signals (e.g., optical signals κ12, κ22, κ32, κ42) to pass through unimpeded. In this way, the microring interleaver DEMUX 1110 can split odd and even optical signals (e.g. optical signals κ11-κ42) onto separate waveguides. In certain examples, the microring interleaver DEMUX 1110 can have a periodic free spectral range (FSR). This FSR can enable the microring interleaver DEMUX 1110 to "drop" optical signals with wavelengths that are spaced a certain distance apart. For example, the FSR of the microring interleaver DEMUX can be tuned to "drop" optical signals with odd wavelengths corresponding to the wavelengths of the optical signals κ11, κ21, κ31, and κ41. In certain embodiments, these odd wavelengths can be spaced approximately 20 nm apart. The even and odd optical signals can be routed to the DEMUXs 1120 and 1122, respectively, via their respective waveguides. The DEMUXs 1120 and 1122 can then distribute the received optical signals to separate waveguides according to wavelength. Specifically, the DEMUX 1120 can distribute optical signals with odd wavelengths (e.g., optical signals κ11, κ21, κ31, κ41) to four separate waveguides according to wavelength. For example, the DEMUX 1120 can distribute the optical signal κ11 to a first waveguide, the optical signal κ21 to a second waveguide, the optical signal κ31 to a third waveguide, and the optical signal κ41 to a fourth waveguide. DEMUX 1122 can split optical signals with even wavelengths (e.g. optical signals κ12, κ22, κ32, κ42) in the same / similar way.The DEMUXs 1120 and 1122 can be, among other things, grid filters, microrings, array waveguide grids and echelle grid DEMUXs, which can be designed / engineered / procured from readily available silicon photonics foundry process design kits. An optical signal of a specific wavelength can be guided via its own waveguide to a Mach-Zehnder modulator, which is calibrated to modulate optical signals of that specific wavelength. For example, the optical signal κ11 can be guided to the optical modulator 1131, which can be calibrated to modulate optical signals of the wavelength of the optical signal κ11. The other optical signals can be modulated in the same or a similar manner. The odd-numbered modulated optical signals (which can be represented as κ'11, κ'21, κ'31, κ'41) can be routed to the MUX 1140, and the even-numbered modulated optical signals (which can be represented as κ'12, κ'22, κ'32, κ'42) to the MUX 1142. In the same / similar manner as described in the preceding figures, the MUX 1140 can combine the odd-numbered modulated optical signals on one waveguide, and the MUX 1142 can combine the even-numbered modulated optical signals on another waveguide. These two waveguides can then transmit the modulated optical signals to the microring interleaver MUX 1150. A microring interleaver MUX can be an optical device that combines optical signals with odd and even wavelengths on a common fiber / waveguide. The 1150 microring interleaver MUX can act as a drop filter for optical signals of specific wavelengths. In particular, the 1150 microring interleaver MUX can be tuned to drop odd-wave modulated optical signals (e.g., κ'11, κ'21, κ'31, κ'41) onto the waveguide carrying even-wave modulated optical signals, while allowing even-wave modulated optical signals (e.g., κ'12, κ'22, κ'32, κ'42) to pass through unimpeded. In this way, the microring interleaver MUX 1150 can combine odd and even modulated optical signals (e.g., the optical signals κ'11-κ'42) on a single output waveguide.As described below, these modulated optical signals can be forwarded to a waveband receiver, which detects the modulated optical signals. This can correspond to the "reading / extracting" of the data imprinted on the modulated optical signals. In certain examples, the Microring Interleaver MUX 1150 can have a periodic free spectral range (FSR). This FSR can enable the Microring Interleaver MUX 1150 to "drop" optical signals with wavelengths spaced a certain distance apart. For example, the FSR of the Microring Interleaver DEMUX can be tuned to "drop" optical signals with odd wavelengths corresponding to the wavelengths of the modulated optical signals κ'11, κ'21, κ'31, and κ'41. In certain embodiments, these odd wavelengths can be spaced approximately 20 nm apart. Similar to the 800-1000 waveband transmitters, the 1100 waveband transmitter can also be operated with existing CWDM / CWDM-4 technologies. For example, the 1100 waveband transmitter can be combined with existing CWDM-4 technologies by tuning either the odd-numbered optical modulators (i.e., optical modulators 1131, 1133, 1135, 1137) or the even-numbered optical modulators (i.e., optical modulators 1130, 1132, 1134, 1136) to modulate optical signals at the CWDM-4 wavelengths. Similarly, the 1100 waveband transmitter's DEMUXs and MUXs can be calibrated to split or combine optical signals at the CWDM-4 wavelengths. Accordingly, the Waveband Transmitter 1100 can work with both existing CWDM-4 technologies and upscaled technologies that utilize the CWDM wavebands of the present disclosure. Fig. 12 shows another example of a bandwave transmitter according to various examples of the technology disclosed herein. The bandwave transmitter 1200 can be considered a general bandwave transmitter from which the bandwave transmitters 800-1100 can be derived. The waveband transmitter 1200 can comprise the following: a combination of one or more optical demultiplexers 1210; at least one first optical modulator 1220 and one second optical modulator 1222; and a combination of one or more optical multiplexers 1230. These components can be interconnected via different waveguides. The combination of one or more optical multiplexers 1210 can split an input light beam into at least one first post-demultiplex light beam and a second post-demultiplex light beam. The input light beam can contain at least one first optical signal (FS) and one second optical signal (SS). The FS can be a first wavelength of a first CWDM waveband, and the SS can be a second wavelength of the first CWDM waveband. The first CWDM waveband can include at least the first and second wavelengths within a first CWDM passband. The first CWDM passband can include a spectrum of wavelengths that contains a first CWDM wavelength capable of passing through an optical filter. In various examples, the input light beam can contain optical signals of additional CWDM wavebands (e.g., optical signals of a second CWDM waveband, optical signals of a third CWDM waveband, etc.) or optical signals of additional wavelengths within the first CWDM passband / waveband (e.g.,an optical signal with a third wavelength within the first CWDM passband, an optical signal with a fourth wavelength within the first CWDM passband, etc.). A post-demultiplexed light beam can refer to a light beam that has been split by one or more optical demultiplexers (this can include a light beam that was first split by an optical demultiplexer and then combined with another light beam by an optical multiplexer). The first post-demultiplexed light beam can contain at least FS. In various examples, the first post-demultiplexed light beam can contain optical signals with additional wavelengths. For example, in the Waveband Transmitter 900, the first post-demultiplexed light beam would contain FS and SS (whose wavelengths comprise the first and second wavelengths of the first CWDM waveband, respectively). Similarly, the second post-demultiplexed light beam in the Waveband Transmitter 900 would comprise a third optical signal and a fourth optical signal, the third and fourth optical signals being the first and second wavelengths of a second CWDM waveband, respectively. The second post-demultiplexed light beam can contain at least one optical signal with a wavelength other than FS. In certain examples, such as the 800, 1000, and 1100 waveband transmitters, the second post-demultiplexed light beam can include SS. In other examples, such as the 900 waveband transmitter, SS can instead be part of the first post-demultiplexed light beam. Accordingly, the at least one optical signal with a wavelength other than FS can be, for example, a third optical signal, a fourth optical signal, and so on. The third optical signal can have the first wavelength of a second CWDM waveband, the fourth optical signal can have the second wavelength of the second CWDM waveband, and so forth. The combination of one or more optical multiplexers 1210 can split the input light beam into additional post-demultiplex light beams. For example, the combination of one or more optical multiplexers 1210 can split the input light beam into the first post-demultiplex light beam, the second post-demultiplex light beam, a third post-demultiplex light beam, and so on. In certain embodiments, each of these post-demultiplex light beams can include optical signals of a separate CWDM waveband. For example, the first post-demultiplex light beam can include optical signals of a first CWDM waveband, the second post-demultiplex light beam can include optical signals of a second CWDM waveband, the third post-demultiplex light beam can include optical signals of a third CWDM waveband, and so on. The combination of one or more optical demultiplexers 1210 can include any number and any type of optical demultiplexer. For example, the combination of one or more optical demultiplexers 1210 in accordance with the waveband transmitter 800 can include a waveband demultiplexer and several wavelength demultiplexers. As used here, a waveband demultiplexer can refer to an optical demultiplexer that splits an input light beam according to wavelengths. Thus, for example, a waveband demultiplexer can split an input light beam consisting of optical signals from several wavebands into separate light beams consisting of optical signals from each waveband. In some examples, a wavelength demultiplexer can refer to an optical demultiplexer that splits a light beam according to wavelengths.For example, a wavelength demultiplexer can split a light beam consisting of optical signals of multiple wavelengths into separate light beams consisting of optical signals of a single wavelength. Wavelength and waveband demultiplexers can be, among other things, grating filters, microring demultiplexers, array waveguide grating demultiplexers, or echelle grating demultiplexers, which can be designed, constructed, and procured from readily available silicon photonics foundry process design kits. In another example, the combination of one or more optical demultiplexers 1210 in accordance with the waveband transmitter 900 can comprise a single waveband demultiplexer (which can also be designed / constructed / procured from readily available silicon photonics foundry process design kits). In certain examples (e.g., waveband transmitters 1000 or 1100), the combination of one or more optical demultiplexers 1210 can also include interleaver demultiplexers (which can split an input light beam into a first light beam consisting of optical signals with odd wavelengths and a second light beam consisting of optical signals with even wavelengths) and microring interleaver demultiplexers. As described above, a microring interleaver demultiplexer can be a special type of interleaver demultiplexer that acts as a "drop" filter for optical signals with odd wavelengths or optical signals with even wavelengths that are periodically spaced apart on the electromagnetic spectrum. A first optical modulator (i.e., optical modulator 1220) can modulate the first post-demultiplexed light beam by modulating FS. As described above, an optical modulator can be an optical device that transfers data to an optical signal by modulating the optical signal. An optical modulator can be calibrated to modulate optical signals of a specific wavelength. For example, optical modulator 1220 can be calibrated to modulate optical signals with the wavelength of FS (i.e., the first wavelength of the first CWDM waveband). The optical modulator 1220 can be any type of optical modulator. For example, if FS is a first CWDM-4 wavelength, the optical modulator 1220 can be a readily available optical modulator used with existing CWDM-4 technologies. In some examples, the optical modulator 1220 can be a microring modulator tuned to modulate optical signals at the wavelength FS. In other examples, the optical modulator 1220 can be a Mach-Zehnder modulator. A second optical modulator (i.e., optical modulator 1222) can modulate the second post-demultiplexed light beam by modulating the one or more optical signals that have a wavelength other than FS. Like optical modulator 1220, optical modulator 1222 can be any type of optical modulator. Accordingly, optical modulator 1222 can be calibrated / tuned to modulate optical signals of the wavelength of the one or more optical signals that have a wavelength other than FS. For example, if the one or more optical signals that have a wavelength other than FS is SS, optical modulator 1222 can be calibrated / tuned to modulate optical signals of the second wavelength of the first CWDM waveband.In contrast, the optical modulator 1222 can be calibrated / tuned to modulate optical signals of the first wavelength of the second CWDM waveband if the at least one optical signal that has a wavelength other than FS is a third optical signal that is a first wavelength of a second CWDM waveband. In certain cases, the CWDM 1200 waveband transmitter can consist of additional optical modulators. Accordingly, each optical modulator can be calibrated / tuned to modulate optical signals of different wavelengths within various CWDM passbands. A combination of one or more optical multiplexers 1230 can combine the modulated first post-demultiplex light beam and the modulated second post-demultiplex light beam into a modulated output light beam. The combination of one or more optical multiplexers 1230 can include any number and any type of optical multiplexer. For example, the combination of one or more optical multiplexers 1230 in accordance with the waveband transmitter 800 can include several wavelength multiplexers and a waveband multiplexer. A wavelength multiplexer can refer to an optical multiplexer that combines wavelengths. For example, a wavelength multiplexer can combine a first light beam, consisting of a first optical signal of a first wavelength, with a second light beam, consisting of a second optical signal of a second wavelength, into a single light beam. The term "waveband multiplexer," as used here, can refer to an optical multiplexer that combines wavebands.In other words, a waveband multiplexer can combine a first light beam, consisting of optical signals from a first CWDM waveband, with a second light beam, consisting of optical signals from a second CWDM waveband, into a single light beam. Wavelength and waveband multiplexers can include, among others, grating filter, microring, array waveguide grating, and echelle grating multiplexers, which can be designed, constructed, and procured from readily available silicon photonics foundry process design kits. In another example, the combination of one or more optical multiplexers 1230 corresponding to the waveband transmitter 900 can comprise a single waveband multiplexer (which can also be designed / constructed / procured from readily available silicon photonics foundry process design kits). In certain examples (e.g., waveband transmitters 1000 or 1100), the combination of one or more optical multiplexers 1230 can also be interleaver multiplexers (which can combine a first light beam from optical signals of odd wavelengths with a second light beam from optical signals of even wavelengths into a common light beam) and microring interleaver multiplexers (which can be a specific type of interleaver multiplexer that acts as a "drop" filter either for optical signals with odd wavelengths or for optical signals with even wavelengths that have a periodic interval between them). Similar to the 800-1100 waveband transmitters, the 1200 waveband transmitter can also operate with existing CWDM / CWDM-4 technologies. For example, the 1200 waveband transmitter can be combined with existing CWDM-4 technologies by tuning at least the first optical modulator 1220 to modulate optical signals of a first CWDM-4 wavelength. Likewise, the combination of one or more demultiplexers 1210 and the combination of one or more multiplexers 1230 can be calibrated to split or combine optical signals of the CWDM-4 wavelengths. Accordingly, the 1200 waveband transmitter can be operated with both existing CWDM-4 technologies and scaled technologies that utilize the CWDM wavebands of this disclosure. Fig. 13 shows an example of a waveband receiver according to various examples of the technology disclosed herein. The waveband receiver 1300 can consist of a polarization beam splitter, a polarization rotator, two waveband demultiplexers, eight wavelength demultiplexers, eight phase shifters, eight waveguide photodetectors, and various waveguides connecting the aforementioned components. In general, a bandpass receiver can detect modulated optical signals from one or more CWDM wavebands received from a common waveguide. These wavebands can consist of two or more wavelengths. As described above, by detecting modulated optical signals, a bandpass receiver can read / extract the data superimposed on the modulated optical signals. Here, the bandpass receiver 1300 can receive eight modulated optical signals with eight different wavelengths on a single input waveguide (i.e., the optical signals ψ'11, ψ'12, ψ'21, ψ'22, ψ'31, ψ'32, ψ'41, ψ'42). These eight different wavelengths can consist of four CWDM wavebands, each with two wavelengths.For example, the wavelengths of the optical signals ψ'12 and ψ'21 can comprise a first CWDM waveband; the wavelengths of the optical signals ψ'21 and ψ'22 can comprise a second CWDM waveband; the wavelengths of the optical signals ψ'31 and ψ'32 can comprise a third CWDM waveband; and the wavelengths of the optical signals ψ'41 and ψ'42 can comprise a fourth CWDM waveband. In some examples, these CWDM wavebands can be CWDM-4 wavebands. In other examples, the waveband receiver can receive 1300 modulated optical signals with a different number of CWDM wavebands (e.g., optical signals with two wavebands, three wavebands, five wavebands, etc.). Similarly, the CWDM wavebands can consist of additional wavelengths (e.g., three wavelengths per CWDM waveband, four wavelengths per CWDM waveband, etc.). In the specific example shown in Fig. 13, the waveband receiver 1300 receives optical signals from four CWDM wavebands, each CWDM waveband consisting of two wavelengths. In other words, the waveband receiver 1300 can receive eight optical signals on a single input waveguide. Accordingly, the waveband receiver 1300 can operate with any of the waveband light sources and waveband transmitters described in conjunction with Figs. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 to 12. As a reminder, each of these waveband light sources can generate optical signals with eight different wavelengths (consisting of four CWDM wavebands, each with two wavelengths), and each of the waveband transmitters can modulate optical signals with these eight wavelengths. In various examples, the 1300 waveband receiver can implement a polarization diversity scheme. Polarization is a property of transverse waves (e.g., electromagnetic waves) that specifies the geometric orientation of the oscillations. In a transverse wave, the direction of oscillation is perpendicular to the direction of wave motion. An electromagnetic wave such as light consists of a coupled oscillating electric field and an oscillating magnetic field, which are always perpendicular to each other. When light travels in an optical waveguide, its polarization can generally rotate. Therefore, when the 1300 waveband receiver receives the modulated optical signals ψ'11-ψ'42, these signals typically have an unknown polarization. In other words, the orientation of the oscillating electric and magnetic fields of these optical signals may be unknown. In general, the response of optical receivers is polarization-dependent. In other words, an optical receiver may respond more strongly to one polarization than to another. Optical waveguides are also typically polarization-dependent, and photonic integrated circuits are more easily designed for a single polarization. Accordingly, many photonic integrated circuits, especially those in silicon PDKs, are polarization-dependent, and the optical elements built from these waveguides are optimized for a single polarization. In most cases, they are optimized for TE mode. Accordingly, the waveguide 1302 can exhibit a polarization dependency. In other words, the waveguide 1302 can have two modes. The first mode can be a transverse-electrical (TE) mode. The oscillating electromagnetic fields of the modulated optical signals ψ'11–ψ'42 can partially excite the TE mode. This TE mode can have a known polarization state (e.g., a "horizontal" polarization state). The second mode can be a transverse-magnetic (TM) mode. The oscillating electromagnetic fields of the modulated optical signals ψ'11–ψ'42 can partially excite this TM mode. This TM mode can have a known polarization state (e.g., a "vertical" polarization state). As part of the polarization diversity scheme of the 1300 waveband receiver, these two modes can be spatially separated onto two separate waveguides. Accordingly, the waveguide 1302 can guide modulated optical signals ψ'11-ψ'42 to the polarization beam splitter 1310. A polarization beam splitter can refer to an optical device that spatially divides a light beam (e.g., the light beam consisting of modulated optical signals ψ'11-ψ'42) into two physically separate light beams that have known, mutually orthogonal polarization states. Accordingly, the polarization beam splitter 1310 can split the light beam with the modulated optical signals ψ'11-ψ'42 into two separate light beams. The first light beam can contain the TE mode of the input light beam (i.e., the "horizontal" polarization state) and can continue to propagate along the waveguide 1304 (which may only have a single TE mode). The second light beam can contain the TM mode of the input light beam (i.e.,the “vertical” polarization state) and can continue to propagate along waveguide 1306 (which may only exhibit the single TM mode). The modulated optical signals of this first light beam can be represented as modulated optical signals ψ'11(TE)- ψ'42(TE). The modulated optical signals of the second light beam can be represented as optical signals ψ'11(TM)- ψ'42(TM) (not shown). In certain examples, the waveguide 1306 can transmit modulated optical signals ψ'11(TM)- ψ'42(TM) to the polarization rotator 1320. A polarization rotator can refer to an optical device that rotates the polarization state of a light beam. Accordingly, the polarization rotator 1320 can rotate the polarization state of the modulated optical signals ψ'11(TM)- ψ'42(TM) by 90 degrees, so that they also propagate in TE mode. The rotated modulated optical signals can be represented as ψ'11(TE')- ψ'42(TE') and can propagate along the waveguide 1308 in TE mode. After splitting the polarization beam (and in certain examples, polarization rotation), the modulated optical signals of known polarization can be directed to waveband demultiplexers. In particular, waveguide 1304 can transmit modulated optical signals ψ'11(TE)- ψ'42(TE) to waveband demultiplexer 1330, and waveguide 1308 can transmit modulated optical signals ψ'11(TE')- ψ'42(TE') to waveband demultiplexer 1332. The waveband demultiplexers 1330 and 1332 can be the same as / similar to the waveband demultiplexers described in connection with the previous figures. Accordingly, the waveband demultiplexer 1330 can split modulated optical signals ψ'11(TE)- ψ'42(TE) according to wavebands (i.e., modulated optical signals ψ'11(TE) and ψ'12(TE) can be split onto a first waveguide; modulated optical signals ψ'21(TE) and ψ'22(TE) can be split onto a second waveguide, etc.). In the same / similar way, the waveband demultiplexer 1332 can split modulated optical signals ψ'11(TE')- ψ'42(TE') according to waveband (i.e., modulated optical signals ψ'11(TE') and ψ'12(TE') can be split onto a first waveguide; modulated optical signals ψ'21(TE') and ψ'22(TE') can be split onto a second waveguide, etc.). After splitting the modulated optical signals into wavebands, the modulated optical signals can be routed to wavelength demultiplexers 1340–1347. These wavelength demultiplexers can be the same as or similar to those described in connection with the previous figures. Accordingly, the wavelength demultiplexers can split the modulated optical signals into wavelengths. For example, wavelength demultiplexer 1340 can split the modulated optical signals ψ'11(TE) and ψ'12(TE) into two separate waveguides; wavelength demultiplexer 1341 can split the modulated optical signals ψ'21(TE) and ψ'22(TE) into two separate waveguides, and so on.In the same / similar way, the wavelength demultiplexer 1344 can split modulated optical signals ψ'11(TE') and ψ'12(TE') onto two separate waveguides; the wavelength demultiplexer 1345 can split modulated optical signals ψ'21(TE') and ψ'22(TE') onto two separate waveguides, etc. Once the modulated optical signals ψ'11(TE)-ψ'42(TE) (i.e., the optical signals transmitted along waveguide 1304) have been split onto their own separate waveguides, they can be directed to the waveguide photodetectors 1360-1367. A waveguide photodetector can refer to an optical device capable of detecting a modulated optical signal when implemented in a waveguide. In certain examples, the waveguide photodetectors can be calibrated to detect modulated optical signals of a specific wavelength. For example, waveguide photodetector 1360 can be calibrated to detect modulated optical signals with the wavelength of the modulated optical signal ψ'11(TE) (i.e., the first wavelength of the first CWDM waveband).In the same / similar way, the waveguide photodetector 1361 can be calibrated to detect modulated optical signals of the wavelength of the modulated optical signal ψ'12(TE) (i.e., the second wavelength of the first CWDM waveband); the waveguide photodetector 1362 can be calibrated to detect modulated optical signals of the wavelength of the modulated optical signal ψ'21(TE) (i.e., the first wavelength of the second CWDM waveband); the waveguide photodetector 1363 can be calibrated to detect modulated optical signals with the wavelength of the modulated optical signal ψ'22(TE) (i.e., the second wavelength of the second CWDM waveband), etc. In the same / similar manner, modulated optical signals ψ'11(TE')- ψ'42(TE') (i.e., the optical signals transmitted along waveguide 1308) can be transmitted to and detected by waveguide photodetectors 1360-1367. For example, waveguide photodetector 1360 can be calibrated to detect modulated optical signals with the wavelength of the modulated optical signal ψ'11(TE') (i.e., the first wavelength of the first CWDM waveband). In the same / similar manner, waveguide photodetector 1361 can be calibrated to detect modulated optical signals with the wavelength of the modulated optical signal ψ'12(TE') (i.e., the second wavelength of the first CWDM waveband). The waveguide photodetector 1362 can be calibrated to detect modulated optical signals of the wavelength of the modulated optical signal ψ'21(TE')(d.h, the first wavelength of the second CWDM waveband); the waveguide photodetector 1363 can be calibrated to detect modulated optical signals of the wavelength of the modulated optical signal ψ'22(TE')(i.e. the second wavelength of the second CWDM waveband) etc. Accordingly, the waveguide photodetectors 1360 - 1367 can detect modulated optical signals ψ'11(TE)- ψ'42(TE) and ψ'11(TE')- ψ'42(TE'), which can correspond to reading / extracting the data supplied to them. In certain examples, one (or both) of the modulated optical signals ψ'11(TE)- ψ'42(TE) and the modulated optical signals ψ'11(TE')- ψ'42(TE') can be transmitted by one of the phase shifters 1370-1377 before being detected by the waveguide photodetectors 1360-1367. A phase shifter can refer to an optical device that shifts the phase of an optical signal. Accordingly, the waveband receiver 1300 can include phase shifters to account for any polarization modal dispersion in optical fibers and time delays that arise from the modulated optical signals taking different paths to the waveguide photodetectors (e.g., the waveguide 1308 can be longer than the waveguide 1304).For example, modulated optical signals ψ'11(TE') can be passed through the phase shifter 1370 before being directed to the waveguide photodetector 1360. This ensures that the modulated optical signal ψ'11(TE') has the same phase as the modulated optical signal when both are detected by the waveguide photodetector 1360. It may be desirable for the modulated optical signals to have the same phase and to arrive at the same time when detected to ensure that the waveguide photodetectors receive the same data stream from the left and right. Similar to the 800-1200 waveband transmitters, the 1300 waveband receiver can also operate with existing CWDM / CWDM-4 technologies. For example, the 1300 waveband receiver can be combined with existing CWDM-4 technologies by calibrating / tuning the following components: the 1360 waveguide photodetector for detecting modulated optical signals of a first CWDM-4 wavelength; the 1362 waveguide photodetector for detecting modulated optical signals of a second CWDM-4 wavelength; the 1364 waveguide photodetector for detecting modulated optical signals of a third CWDM-4 wavelength; and the 1366 waveguide photodetector for detecting modulated optical signals of a fourth CWDM-4 wavelength. Similarly, the other optical components of the Waveband Receiver 1300 can be calibrated / tuned to operate with these CWDM-4 wavelengths.Accordingly, the Waveband Receiver 1300 can work with both existing CWDM-4 technologies and upscaled technologies that utilize the CWDM wavelengths of the present disclosure. Similar to the waveband devices described above, the waveband receiver 1300 can be built from many readily available components found in silicon photonics and III-V foundry process design kits (e.g., broadband fiber chip couplers, CWDM-4 waveguide photodetectors, etc.). Fig. 14 shows another example of a waveband receiver according to various examples of the currently disclosed technology. The waveband receiver 1400 can consist of a polarization beam splitter, a polarization rotator, two waveband demultiplexers, eight microring resonators / drop filters, various phase shifters, eight waveguide photodetectors, and various waveguides connecting the aforementioned components. Like the Waveband Receiver 1300, the Waveband Receiver 1400 can detect modulated optical signals from one or more CWDM wavebands received from a common waveguide. These wavebands can consist of two or more wavelengths. As described above, by detecting modulated optical signals, a waveband receiver can read / extract the data transmitted on the modulated optical signals. Here, the 1400 waveband receiver can receive eight modulated optical signals with eight different wavelengths on a single input waveguide (i.e., modulated optical signals φ'11, φ'12, φ'21, φ'22, φ'31, φ'32, φ'41, φ'42). These eight different wavelengths can consist of four CWDM wavebands, each with two wavelengths. For example, the wavelengths of the optical signals φ'11 and φ'12 can comprise a first CWDM waveband; the wavelengths of the optical signals φ'21 and φ'22 can comprise a second CWDM waveband; the wavelengths of the optical signals φ'31 and φ'32 can comprise a third CWDM waveband; and the wavelengths of the optical signals φ'41 and φ'42 can comprise a fourth CWDM waveband. In various examples, these CWDM wavebands can be CWMD-4 wavebands.In other examples, the waveband receiver 1400 can receive modulated optical signals with a varying number of CWDM wavebands (e.g., optical signals with two wavebands, three wavebands, five wavebands, etc.). Likewise, the CWDM wavebands can consist of additional wavelengths (e.g., three wavelengths per CWDM waveband, four wavelengths per CWDM waveband, etc.). In the specific example shown in Fig. 14, the waveband receiver 1400 receives modulated optical signals from four CWDM wavebands, each CWDM waveband consisting of two wavelengths. In other words, the waveband receiver 1400 can receive eight optical signals on a single input waveguide. Accordingly, the waveband receiver 1400 can operate with any of the waveband light sources and waveband transmitters described in conjunction with Figs. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 to 12. As a reminder, each of these waveband light sources can generate optical signals with eight different wavelengths (consisting of four CWDM wavebands, each with two wavelengths), and each of the waveband transmitters can modulate optical signals with these eight wavelengths. Like the Waveband Receiver 1300, the Waveband Receiver 1400 can also implement a polarization diversity scheme. Accordingly, the waveguide 1402 can exhibit polarization dependence. In other words, the waveguide 1402 can have two modes. The first mode can be a transverse electric (TE) mode. The oscillating electric fields of the modulated optical signals φ'11-φ'42 can partially excite this TE mode. This TE mode can have a known polarization state (e.g., a "horizontal" polarization state). The second mode can be a transverse magnetic (TM) mode. The oscillating magnetic fields of the modulated optical signals φ'11-φ'42 can partially excite this TM mode. This TM mode can have a known polarization state (e.g., a "vertical" polarization state). As part of the polarization diversity scheme of the waveband receiver 1400, these two modes can be spatially separated onto two separate waveguides. Accordingly, waveguide 1402 can transmit modulated optical signals φ'11-φ'42 to polarization beam splitter 1410. Polarization beam splitter 1410 can split the light beam containing the modulated optical signals φ'11-φ'42 into two separate light beams. The first light beam can contain the TE mode of the input light beam (i.e., the "horizontal" polarization state) and can continue to propagate along waveguide 1404 (which may only have a single TE mode). The second light beam can contain the TM mode of the input light beam (i.e., the "vertical" polarization state) and can continue to propagate along waveguide 1406 (which may only have the single TM mode). The modulated optical signals of this first light beam can be represented as modulated optical signals φ'11(TE)-φ'42(TE).The modulated optical signals of the second light beam can be represented as optical signals φ'11(TM)- φ'42(TM) (not shown). In certain examples, the waveguide 1406 can transmit modulated optical signals φ'11(TM)- φ'42(TM) to the polarization rotator 1420. Accordingly, the polarization rotator 1420 can rotate the polarization state of the modulated optical signals φ'11(TM)- φ'42(TM) by 90 degrees, so that they also propagate in TE mode. The rotated modulated optical signals can be represented as φ'11(TE')- φ'42(TE') and can propagate along the waveguide 1408 in TE mode. After splitting the polarization beam (and in certain examples, polarization rotation), the modulated optical signals of known polarization can be directed to waveband demultiplexers. In particular, waveguide 1404 can transmit the modulated optical signals φ'11(TE)- φ'42(TE) to waveband demultiplexer 1430, and waveguide 1408 can transmit the modulated optical signals φ'11(TE')- φ'42(TE') to waveband demultiplexer 1432. The waveband demultiplexers 1430 and 1432 can be the same as or similar to the waveband demultiplexers described in connection with the previous figures. Accordingly, the waveband demultiplexer 1430 can split the modulated optical signals φ'11(TE) to φ'42(TE) according to the waveband. In particular, modulated optical signals φ'11(TE) and φ'12(TE) can be split onto waveguide 1440; modulated optical signals φ'21(TE) and φ'22(TE) can be split onto waveguide 1442; modulated optical signals φ'31(TE) and φ'32(TE) can be split onto waveguide 1444. Modulated optical signals φ'41(TE) and φ'42(TE) can be split onto the waveguide 1446. Similarly, the waveband demultiplexer 1432 can split modulated optical signals φ'11(TE') and φ'42(TE') according to the waveband.In particular, modulated optical signals φ'11(TE') and φ'12(TE') can be split on waveguide 1440; modulated optical signals φ'21(TE') and φ'22(TE') can be split on waveguide 1442; modulated optical signals φ'31(TE') and φ'32(TE') can be split on waveguide 1444; and modulated optical signals φ'41(TE') and φ'42(TE') can be split on waveguide 1446. As described above, each of the waveguides 1440–1446 can transmit modulated optical signals of a common CWDM waveband after demultiplexing. In particular, waveguide 1440 can transmit modulated optical signals of the first CWDM waveband (i.e., modulated optical signals φ'11(TE), φ'12(TE), φ'11(TE'), and φ'12(TE')); waveguide 1442 can transmit modulated optical signals of the second CWDM waveband (i.e., modulated optical signals φ'21(TE), φ'22(TE), φ'21(TE'), and φ'22(TE')). The waveguide 1444 can transmit modulated optical signals of the third CWDM waveband (i.e., modulated optical signals φ'31(TE), φ'32(TE), φ'31(TE') and φ'32(TE')); and the waveguide 1446 can transmit modulated optical signals of the fourth CWDM waveband (i.e., modulated optical signals φ'41(TE), φ'42(TE), φ'41(TE') and φ'42(TE')). Two microring resonators can be located next to each of the waveguides 1440–1446. As described above, a microring resonator can refer to a closed waveguide that couples an input waveguide to an output waveguide. Here, the microring resonators couple waveguides 1440–1446 to the waveguides containing waveguide photodetectors 1460–1467. Specifically: microring resonator 1450 couples waveguide 1440 to the waveguide containing waveguide photodetector 1460; microring resonator 1451 couples waveguide 1440 to the waveguide containing waveguide photodetector 1461; microring resonator 1452 couples waveguide 1442 to the waveguide containing waveguide photodetector 1462. The microring resonator 1453 couples the waveguide 1442 to the waveguide containing the waveguide photodetector 1463;Microring resonator 1454 couples waveguide 1444 to the waveguide containing waveguide photodetector 1464; microring resonator 1455 couples waveguide 1444 to the waveguide containing waveguide photodetector 1465; microring resonator 1456 couples waveguide 1446 to the waveguide containing waveguide photodetector 1466; and microring resonator 1457 couples waveguide 1446 to the waveguide containing waveguide photodetector 1467. Similar to the other components described above, these microring resonators can be designed / procured from readily available silicon photonics and III-V foundry process design kits. In the example of the waveband receiver 1400, the eight microring resonators can serve as blocking filters for optical signals of specific wavelengths. For example, the microring resonator 1450 can be tuned to "drop" modulated optical signals of the first wavelength of the first CWDM waveband (e.g., modulated optical signals φ'11(TE) and φ'11(TE')) while allowing modulated optical signals of other wavelengths to pass through unimpeded. Accordingly, the microring resonator 1450 can project modulated optical signals φ'11(TE) and φ'11(TE') onto the waveguide containing the waveguide photodetector 1460, while allowing modulated optical signals φ'12(TE) and φ'12(TE') to pass through unimpeded. In the same / similar way, the microring resonator 1451 can project modulated optical signals φ'12(TE) and φ'12(TE') onto the waveguide containing the waveguide photodetector 1461, while allowing modulated optical signals φ'11(TE) and φ'11(TE') to pass through unhindered.The microring resonators 1452 - 1457 can be tuned in the same / similar way so that they “drop” modulated optical signals of one wavelength per CWDM waveband while allowing modulated optical signals of other wavelengths to pass through unhindered. Accordingly, the waveguide photodetector 1460 can detect modulated optical signals φ'11(TE) and φ'11(TE'); the waveguide photodetector 1461 can detect modulated optical signals φ'12(TE) and φ'12(TE'); the waveguide photodetector 1462 can detect modulated optical signals φ'21(TE) and φ'21(TE'); the waveguide photodetector 1463 can detect modulated optical signals φ'22(TE) and φ'22(TE'); the waveguide photodetector 1464 can detect modulated optical signals φ'31(TE) and φ'31(TE'); the waveguide photodetector 1465 can detect modulated optical signals φ'32(TE) and φ'32(TE'); Waveguide photodetector 1466 can detect modulated optical signals φ'41(TE) and φ'41(TE'); and waveguide photodetector 1467 can detect modulated optical signals φ'42(TE) and φ'42(TE'). As described above, detecting a modulated optical signal can correspond to reading / extracting the data transmitted on it. In certain examples, one (or both) of the modulated optical signals φ'11(TE)- φ'42(TE) and the modulated optical signals φ'11(TE')- φ'42(TE') can be transmitted by phase shifters (PS) located on the same waveguides as the waveguide photodetectors 1460-1467 before being detected by the waveguide photodetectors 1460-1467. These phase shifters can be used to compensate for any polarization modal dispersion in optical fibers and time delays that arise from the modulated optical signals taking different paths to the waveguide photodetectors (e.g., waveguide 1408 may be longer than waveguide 1404). Similar to the Waveband Receiver 1300, the Waveband Receiver 1400 can also operate with existing CWDM / CWDM-4 technologies. For example, the Waveband Receiver 1400 can be combined with existing CWDM-4 technologies by calibrating / tuning the following: the Waveguide Photodetector 1460 to detect modulated optical signals of a first CWDM-4 wavelength; the Waveguide Photodetector 1462 to detect modulated optical signals of a second CWDM-4 wavelength; the Waveguide Photodetector 1464 to detect modulated optical signals of a third CWDM-4 wavelength; and the Waveguide Photodetector 1466 to detect modulated optical signals of a fourth CWDM-4 wavelength. Similarly, the other optical components of the Waveband Receiver 1400 can be calibrated / tuned to operate with these CWDM-4 wavelengths.Accordingly, the Waveband Receiver 1400 can work with both existing CWDM-4 technologies and upscaled technologies that utilize the CWDM wavelengths of the present disclosure. Similar to the waveband devices described above, the waveband receiver 1400 can be built from many readily available components found in silicon photonics and III-V foundry process design kits (e.g., broadband fiber chip couplers, CWDM-4 waveguide photodetectors, etc.). Fig. 15 shows another example of a waveband receiver according to various examples of the technology disclosed herein. The waveband receiver 1500 can be considered a general waveband receiver from which the waveband receivers 1300 and 1400 can be derived. The waveband receiver 1500 can comprise the following: a first combination of one or more optical demultiplexers 1510 and at least one first optical photodetector 1520. These components can be interconnected by different waveguides. In certain examples, the waveband receiver 1500 can also comprise a polarization beam splitter 1530, a polarization rotator 1540, optical phase shifters (not shown), and other optical devices / components (e.g., a second combination of one or more optical demultiplexers 1512, a second optical photodetector 1522, etc.). The first combination of one or more optical demultiplexers 1510 can split a first version of a modulated input light beam into at least one first post-demultiplex light beam and one second post-demultiplex light beam. The first version of the modulated input light beam can include at least one first version of a first modulated optical signal (FMS1) and one first version of a second modulated optical signal (SMS1). FMS1 can be a first wavelength within a first CWDM passband, and SMS1 can be a second wavelength within the first CWDM passband. As described above, the first CWDM passband can include a spectrum of wavelengths that contains a CWDM wavelength capable of passing through an optical filter. In certain examples, the first CWDM passband can include the first CWDM-4 wavelength. FMS1 can refer to or be derived from a first modulated optical signal (FMS) in various ways. In some examples, FMS1 can be identical to FMS. In other examples, FMS1 can be the transverse electrical (TE) mode of FMS or the transverse magnetic (TM) mode of FMS. In still other examples, FMS1 can be a TM mode of FMS that has been rotated by 90 degrees so that it propagates in the TE mode. As described above, FMS can be a modulated version of a first optical signal (FS). FS can be one of the modes shown in conjunction with Figures 8-12. SMS1 can be in the same / similar relationship to SMS. The first post-demultiplexed light beam can contain at least FMS1. As described above, a post-demultiplexed light beam can refer to a light beam that has been split by one or more optical demultiplexers. In various examples, the first post-demultiplexed light beam can contain additional modulated optical signals of different wavelengths. For example, in the case of the Waveband Receiver 1400 (which may be derived from the Waveband Receiver 1500), the first post-demultiplexed light beam would also contain the first version of the second modulated optical signal (i.e., SMS1). The second post-demultiplexed light beam can contain at least one first version of a modulated optical signal having a wavelength other than FMS1. In certain examples (e.g., Waveband Receiver 1300), the first version of the modulated optical signal having a wavelength other than FMS1 can be SMS1. In other examples (e.g., Waveband Transmitter 1400), the first version of the modulated optical signal having a wavelength other than FMS1 can be a first version of a third modulated optical signal (not shown). In some of these examples, the first version of the third modulated optical signal can be a first wavelength within a second CWDM passband. The first optical photodetector (i.e., the optical photodetector 1520) can detect the first post-demultiplexed light beam by detecting FMS1. An optical photodetector can refer to an optical device capable of detecting a modulated optical signal. An optical photodetector can be calibrated to detect modulated optical signals of a specific wavelength. For example, the optical photodetector 1520 can be calibrated to detect modulated optical signals of the wavelength of FMS1 (i.e., the first wavelength within the first CWDM passband). The first optical photodetector 1520 can be various types of optical photodetectors, including a waveguide photodetector. As described above, the 1500 waveband receiver can include additional components. For example, the 1500 waveband receiver can include a 1530 polarization beam splitter. The 1530 polarization beam splitter can split the modulated input light beam into a first version and a second version. The second version can comprise at least a second version of the first modulated optical signal (FMS2) and a second version of the second modulated optical signal (SMS2). In certain examples, the first version of the modulated input light beam can be the TE mode of the modulated input light beam, and the second version of the modulated input light beam can be the TM mode of the modulated input light beam. In some of these examples, the waveband receiver 1500 can include a polarization inverter 1540 that rotates the second version of the modulated input light beam by 90 degrees so that it also propagates in the TE mode. In examples where the waveband receiver 1500 splits the modulated input light beam into a first and a second version of the modulated input light beam, the waveband receiver 1500 can include a second combination of one or more optical demultiplexers 1512 that splits the second version of the modulated input light beam into a third post-demultiplex light beam and a fourth post-demultiplex light beam. The third post-demultiplex light beam can contain at least FMS2. In various examples, the third post-demultiplex light beam can contain additional modulated optical signals with different wavelengths. For example, in the case of the Waveband Receiver 1400 (which may be derived from the Waveband Receiver 1500), the third post-demultiplex light beam would also contain the second version of the second modulated optical signal (i.e., SMS2). The fourth post-demultiplex light beam can include at least one second version of a modulated optical signal having a wavelength different from FMS2. In certain examples (e.g., Waveband Receiver 1300), the second version of the single modulated optical signal having a wavelength different from FMS2 can be SMS2. In other examples (e.g., Waveband Transmitter 1400), the second version of the single modulated optical signal having a wavelength different from FMS2 can be a second version of a third modulated optical signal (not shown). In some of these examples, the second version of a third modulated optical signal can be a first wavelength within a second CWDM passband. The 1500 waveband receiver can also include additional optical photodetectors. For example, the 1500 waveband receiver can have a second optical photodetector 1522 that detects modulated optical signals with a different wavelength than FMS1 and FMS2. The second optical photodetector can, for example, be calibrated to detect modulated optical signals of a second wavelength of the first CWDM passband (e.g., SMS1 and SMS2), a first wavelength of a second CWDM passband, and so on. Similar to the 1300 and 1400 bandpass receivers, the 1500 bandpass receiver can also operate with existing CWDM / CWDM-4 technologies. For example, the 1500 bandpass receiver can be combined with existing CWDM-4 technologies by calibrating / tuning the first optical photodetector 1520 to detect modulated optical signals of a first CWDM-4 wavelength. Additional optical photodetectors that may be included in the 1500 bandpass receiver can also be calibrated to detect modulated optical signals with CWDM-4 wavelengths. Similarly, the other optical components of the 1500 bandpass receiver (e.g., the combination of one or more demultiplexers) can be calibrated / tuned to operate with these CWDM-4 wavelengths.Accordingly, the Waveband Receiver 1500 can work with both existing CWDM-4 technologies and upscaled technologies that utilize the CWDM wavebands of the present disclosure. Furthermore, the Waveband Receiver 1500, similar to the Waveband Devices described above, can be built using many readily available components from silicon photonics and III-V Foundry process design kits (e.g., broadband fiber chip couplers, CWDM-4 waveguide photodetectors, etc.). As used herein, the term "or" can be understood in both an inclusive and an exclusive sense. Furthermore, the description of resources, processes, or structures in the singular is not to be understood as excluding the plural. Conditional expressions such as "may" or "could" are generally intended, unless explicitly stated otherwise or understood differently in context, to indicate that certain examples include certain features, elements, and / or steps, while other examples do not. Unless explicitly stated otherwise, the terms and expressions used in this document, as well as their variations, are to be understood as open rather than restrictive. Adjectives such as "conventional," "traditional," "normal," "standard," "known," and terms with similar meanings are not to be understood as limiting the described subject matter to a specific period or to an item available at a particular time, but should be understood as encompassing conventional, traditional, normal, or standard technologies that may be available or known now or at any time in the future.The presence of expansive words and phrases such as "one or more", "at least", "but not limited to" or similar phrases in some cases is not to be understood as implying that the narrower case is intended or required when such expansive phrases are not present.

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