Amplified spontaneous emission light source

Abstract

An amplified spontaneous emission (ASE) light source is disclosed. The ASE light source includes a superluminescent light emitting diode (SLED) chip and a beam modification assembly coupled to the SLED chip. The SLED chip emits two light beams in transverse electric (TE) polarization mode. The beam modification assembly receives the light beams and rotates the TE polarization mode of one light beam to transverse magnetic (TM) polarization mode. Further, the light beam having the TM polarization mode is combined with the light beam having the TE polarization mode into a combined light beam. The combined light beam is outputted from the ASE light source. The combined light beam is non-polarized.

Description

AMPLIFIED SPONTANEOUS EMISSION LIGHT SOURCECROSS-REFERENCE TO RELATED APPLICATIONS / INCORPORATION BY REFERENCE

[0001] This Patent Application makes reference to, claims priority to, and claims the benefit of US provisional application 63 / 614,982 filed December 27, 2023, the contents of which is hereby incorporated herein by reference in its entirety.FIELD

[0002] Various embodiments of the disclosure relate to light sources. More particularly, amplified spontaneous emission light sources.BACKGROUND

[0003] The amplified spontaneous emission (ASE) light source is a wide broadband coherent light source, with application space in optical spectral sensing, such as optical tomography, fiber-optic gyroscope, spectrum detection, and the like.

[0004] The wide bandwidth high optical power emission can be typically achieved from erbium- doped optical fibers. The erbium ions are fused within the optical fiber core and they can be excited by high-energy photons. A broadband optical spectrum is then emitted upon relaxation of the erbium ions from higher energy states through spontaneous emission. This erbium-doped fiberbased ASE light source requires a 980 nanometer (nm) laser light source as an optical pump to drive the ASE emission from the doped fiber. Arising from the energy states of the erbium dopant, the emission spectrum resides between 1528 to 1564nm.

[0005] A similar optical emission spectrum can be achieved using a semiconductor-based light source. Optical emission can be achieved by pumping electrons into a quantum well layer where the electron-hole carriers in the device recombine, releasing optical energy in the process. The optical waveguides are terminated with an optical absorber at the back facet and an anti-reflection (AR) coating at the front facet. The front facet is also angled to further suppress any back-reflection of the spontaneous photon-emitted light. The design of the quantum well layer structure and the active waveguide is critical to achieving spontaneous emission across a wide spectral bandwidth. Such devices are classified as superluminescent light emitting diode (SLED) or amplified spontaneous emission (ASE) light sources. Due to the wide tailorable bandgap of the III-V semiconductor material, the emission spectrum can be extended out of C-band applications.

[0006] Comparing the erbium-doped fiber-based ASE sources with semiconductor-based ASE sources, the power efficiency of fiber-based ASE is limited by the power consumption of the 980nm optical pump. The fiber-based ASE source has a larger form factor as compared to the semiconductor-based ASE source due to the need for various optical splitter and filter components. Due to the semiconductor epitaxial structure of the quantum well, the output of the typical SLED is characteristically dominant in the transverse electric (TE) polarization mode. Hence, functionally, the SLED is unable to act as a replacement for the erbium-doped fiber-based applications that require a non-polarized light source. The intrinsic degree of polarization of an SLED can be reduced by a combination of, and not limited to, strained quantum well design, number of quantum wells, and quantum well thickness. However, optimization for a low degree of polarization introduces trade-offs with lower optical power and a narrower gain spectrum. Additionally, an output power of an SLED module falls short of matching with the erbium-doped fiber-based ASE source.

[0007] In light of the foregoing, there is a need for a technical solution that overcomes the above- mentioned problems.SUMMARY

[0008] An amplified spontaneous emission light source is provided substantially as shown in, and / or described in connection with, at least one of the figures, as set forth more completely in the claims.

[0009] In an embodiment of the present disclosure, an amplified spontaneous emission (ASE) light source is disclosed. The ASE light source may include a superluminescent light emitting diode (SLED) chip and a beam modification assembly that is optically coupled to the SLED chip. The SLED chip may be configured to emit a first light beam and a second light beam. The first and second light beams are emitted in a first polarization mode. The beam modification assembly may be configured to receive the first light beam and the second light beam and rotate the first polarization mode of the first light beam to a second polarization mode. The beam modification assembly may be further configured to combine the first light beam having the second polarization mode with the second light beam having the first polarization mode into a third light beam and output the third light beam.

[0010] In another embodiment, an ASE light circuit is disclosed. The ASE light circuit may include a plurality of ASE light sources and a set of mirrors optically coupled to the plurality of ASE light sources. Each ASE light source of the plurality of ASE light sources comprises an SLED chip and a beam modification assembly that is optically coupled to the SLED chip. The SLED chip may be configured to emit a first light beam and a second light beam. The first and second light beams are emitted in a first polarization mode. Further, the set of mirrors may be configured to receive the third light beam from each ASE light source of the plurality of ASE light sources and combine thethird light beam from each ASE light source of the plurality of ASE light sources to a fourth light beam. The set of mirrors may be configured to output the fourth light beam.

[0011] In yet another embodiment, a method of amplified spontaneous emission (ASE) in an ASE light source is disclosed. The method may include emitting a first light beam and a second light beam, by a superluminescent light emitting diode (SLED) chip of the ASE light source. The first and second light beams are emitted in a first polarization mode. The method may further include receiving, by a beam modification assembly of the ASE light source, the first light beam and the second light beam. Further, the method may include rotating, by the beam modification assembly, the first polarization mode of the first light beam to a second polarization mode. Additionally, the method may include combining, by the beam modification assembly, the first light beam having the second polarization mode with the second light beam having the first polarization mode into a third light beam. The method may further include outputting, by the beam modification assembly, the third light beam.

[0012] In some embodiments, the SLED chip may include a first SLED configured to emit the first light beam, and a second SLED configured to emit the second light beam.

[0013] In some embodiments, the ASE light source may further include a submount coupled to the SLED chip. The first SLED is assembled on the submount such that the emitted first light beam is orthogonal to the submount. Similarly, the second SLED is assembled on the submount such that the emitted second light beam is orthogonal to the submount.

[0014] In some embodiments, the submount is a heat dissipating submount.

[0015] In some embodiments, the ASE light source may further include a thermoelectric cooler coupled to the SLED chip and configured to cool the SLED chip.

[0016] In some embodiments, the beam modification assembly may include an array of microlenses configured to receive the first light beam and the second light beam, and collimate the first light beam and the second light beam.

[0017] In some embodiments, the beam modification assembly may further include a half-wave plate optically coupled to the array of micro-lenses and configured to rotate the first polarization mode of the first light beam to the second polarization mode. The first light beam is collimated into the half-wave plate from the array of micro-lenses.

[0018] In some embodiments, the beam modification assembly may further include a beam deflector optically coupled to the half-wave plate, and a polarization beam combiner optically coupled to the beam deflector and the array of micro-lenses. The beam deflector is configured todeflect the first light beam with the second polarization mode to the polarization beam combiner. The polarization beam combiner is configured to receive the first light beam and second light beam, combine the first light beam and the second light beam into the third light beam, and output the third light beam.

[0019] In some embodiments, the first light beam is deflected to the polarization beam combiner at a right angle.

[0020] In some embodiments, the beam modification assembly may further include a clear glass optically coupled to the array of micro-lenses and the polarization beam combiner. The clear glass is configured to guide the second light beam from the array of micro-lenses to the polarization beam combiner.

[0021] In some embodiments, a high-reflection coating is deposited between the half- wave plate and the clear glass to prevent cross-talk between the first light beam and the second light beam.

[0022] In some embodiments, the array of micro-lenses may include a first micro-lens configured to collimate the first light beam to the half-wave plate and a second micro-lens configured to collimate the second light beam to the clear glass.

[0023] In some embodiments, the third light beam is a non-polarized light beam.

[0024] In some embodiments, a degree of polarization of the third light beam is low in comparison to degree of polarizations of the first and second light beams.

[0025] In some embodiments, the degree of polarization of the third light beam is less than 0.1.

[0026] In some embodiments, the third light beam has a polarization extinction ratio of less than 0.9 decibels.

[0027] In some embodiments, the first polarization mode corresponds to transverse electric mode and the second polarization mode corresponds to transverse magnetic mode.

[0028] In some embodiments, the fourth light beam is a non-polarized light beam.

[0029] These and other features and advantages of the present disclosure may be appreciated from a review of the following detailed description of the present disclosure, along with the accompanying figures in which like reference numerals refer to like parts throughout.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings illustrate the various embodiments of systems, methods, and other aspects of the disclosure. It will be apparent to a person skilled in the art that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. In some examples, one element may be designed as multiple elements, or multiple elements may be designed as one element. In some examples, an element shown as an internal component of one element may be implemented as an external component in another, and vice versa.

[0031] Various embodiments of the present disclosure are illustrated by way of example, and not limited by the appended figures, in which like references indicate similar elements, and in which:

[0032] FIG. 1 illustrates an amplified spontaneous emission (ASE) light source in accordance with an embodiment of the present disclosure;

[0033] FIG. 2 illustrates a schematic block diagram of the ASE light source in accordance with an embodiment of the present disclosure;

[0034] FIG. 3 illustrates a top view of the ASE light source in accordance with an embodiment of the present disclosure;

[0035] FIG. 4 illustrates a schematic block diagram of an ASE light circuit in accordance with an embodiment of the present disclosure; and

[0036] FIG. 5 represents a flowchart that illustrates a method of amplified spontaneous emission in the ASE light source in accordance with an embodiment of the present disclosure.

[0037] Further areas of applicability of the present disclosure will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description of exemplary embodiments is intended for illustration purposes only and is, therefore, not intended to necessarily limit the scope of the present disclosure.DETAILED DESCRIPTION

[0038] The present disclosure is best understood with reference to the detailed figures and description set forth herein. Various embodiments are discussed below with reference to the figures. However, those skilled in the art will readily appreciate that the detailed descriptions given herein with respect to the figures are simply for explanatory purposes as the methods and systems may extend beyond the described embodiments. In one example, the teachings presented and the needs of a particular application may yield multiple alternate and suitable approaches to implement thefunctionality of any detail described herein. Therefore, any approach may extend beyond the particular implementation choices in the following embodiments that are described and shown.

[0039] References to “an embodiment”, “another embodiment”, “yet another embodiment”, “one example”, “another example”, “yet another example”, “for example”, and so on, indicate that the embodiment(s) or example(s) so described may include a particular feature, structure, characteristic, property, element, or limitation, but that not every embodiment or example necessarily includes that particular feature, structure, characteristic, property, element or limitation. Furthermore, repeated use of the phrase “in an embodiment” does not necessarily refer to the same embodiment.

[0040] Various embodiments of the present disclosure disclose an amplified spontaneous emission (ASE) light source. The ASE light source includes a superluminescent light emitting diode (SLED) chip and a beam modification assembly coupled to the SLED chip. The SLED chip emits two light beams in transverse electric (TE) polarization mode. The beam modification assembly receives the light beams and rotates the TE polarization mode of one light beam to transverse magnetic (TM) polarization mode. Further, the light beam having the TM polarization mode is combined with the light beam having the TE polarization mode into a combined light beam. The combined light beam is outputted from the ASE light source. The combined light beam is non-polarized. The present invention addresses limitations of existing systems such as power output, polarization stability, spectral range, and compactness. By leveraging the SLED chip that includes two SLEDs, the combined light beam with high optical power and a low degree of polarization in comparison to conventional systems is achieved by the disclosed ASE light source. Additionally, the form factor of the disclosed ASE light source is less in comparison to the form factors of existing ASE erbium- doped fiber-based light sources.

[0041] FIG. 1 illustrates an amplified spontaneous emission (ASE) light source 100 in accordance with an embodiment of the present disclosure. ASE refers to a process in which light is generated and amplified based on spontaneous emission of photons. The ASE light source 100 may include a superluminescent light emitting diode (SLED) chip 102 and a beam modification assembly 104. The SLED chip 102 may be configured to emit a first light beam FB and a second light beam SB. The first light beam FB and the second light beam SB may be emitted in a first polarization mode.

[0042] Polarization mode of a light beam refers to an orientation and behavior of an electric field vector of the light beam as the light beam propagates through space or a medium. The polarization mode describes how the electric field oscillates relative to the direction of propagation of the light beam. The polarization mode may correspond to a transverse electric (TE) mode or a transverse magnetic (TM) mode. In the TE mode, the electric field vector of the light beam is perpendicular to a direction of the propagation of the light beam. In the TM mode, a magnetic field vector of thelight beam is perpendicular to the direction of the propagation of the light beam. The first polarization mode corresponds to the TE mode.

[0043] The beam modification assembly 104 may be optically coupled to the SLED chip 102. The beam modification assembly 104 may be configured to receive the first light beam FB and the second light beam SB from the SLED chip 102. Further, the beam modification assembly 104 may be configured to rotate the first polarization mode of the first light beam FB to a second polarization mode. The second polarization mode may correspond to the TM mode. The beam modification assembly 104 may be further configured to combine the first light beam FB having the second polarization mode with the second light beam SB having the first polarization mode into a third light beam TB.

[0044] In other words, the first light beam FB with TM mode is combined with the second light beam SB with TE mode. Thus, the third light beam TB corresponds to a non-polarized light beam. Additionally, a degree of polarization of the third light beam TB is low in comparison to degree of polarizations of the first and second light beams FB and SB. Further, the beam modification assembly 104 may be configured to output the third light beam TB. The ASE light source 100 is further explained in detail in conjunction with FIG. 2.

[0045] FIG. 2 illustrates a schematic block diagram of the ASE light source 100 in accordance with an embodiment of the present disclosure. Referring to FIG. 2, the SLED chip 102 may include a first SLED 202 and a second SLED 204. An SLED refers to a type of LED that emits incoherent light with high intensity over a broad spectrum. The first SLED 202 may be configured to emit the first light beam FB and the second SLED 204 may be configured to emit the second light beam SB. The first light beam FB and the second light beam SB are emitted in the first polarization mode.

[0046] The ASE light source 100 may further include a submount 206 coupled to the SLED chip 102. The first SLED 202 is assembled on the submount 206 such that the emitted first light beam FB is orthogonal to the submount 206. Similarly, the second SLED 204 is assembled on the submount 206 such that the emitted second light beam is orthogonal to the submount 206. Additionally, the submount 206 is made of thermally conductive material, thereby the submount 206 facilitates dissipation of heat generated by the SLED chip 102 during the emission of the first and second light beams FB and SB. In other words, the submount 206 is a heat dissipating submount. In some embodiments, the submount 206 may facilitate routing of electrical drive currents to the SLED chip 102 via conductive traces or bonding pads.

[0047] The beam modification assembly 104 may include an array of micro-lenses 208, a half-wave plate 210, a beam deflector 212, a clear glass 214, and a polarization beam combiner 216. The beammodification assembly 104 may modify spatial and polarization characteristics of the first and second light beams FB and SB to output the third light beam TB. The third light beam has high power and a low degree of polarization (DOP) compared to the light beam outputted by conventional ASE light sources.

[0048] The array of micro-lenses 208 may be optically coupled to the SLED chip 102 and configured to receive the first and second light beams FB and SB from the SLED chip 102. The array of micro-lenses 208 may be further configured to collimate the first light beam FB and the second light beam SB. The first light beam FB and the second light beam SB emitted from the SLED chip may be divergent in nature, thus the array of micro-lenses 208 collimates the first and second light beams FB and SB in a horizontal direction. The array of micro-lenses 208 may include a first micro-lens 208a and a second micro-lens 208b. The first micro-lens 208a may be optically coupled to the first SLED 202 and the second micro-lens 208b may be optically coupled to the second SLED 204. Further, the first micro-lens 208a may be configured to receive the first light beam FB and collimate the first light beam FB. Similarly, the second micro-lens 208b may be configured to receive the second light beam SB and collimate the second light beam SB. The first micro-lens 208a may collimate the first light beam FB into the half-wave plate 210. Further, the second micro-lens 208b may collimate the second light beam SB into the clear glass 214.

[0049] The half- wave plate 210 may be optically coupled to the array of micro-lenses 208. Particularly, the half-wave plate 210 may be optically coupled to the first micro- lens 208a. The half-wave plate 210 is an optical device that modifies a polarization mode of a light beam passing through it. The half- wave plate 210 may be configured to rotate the first polarization mode of the first light beam FB to the second polarization mode. In other words, the first micro-lens 208a may rotate the TE mode of the first light beam FB to the TM mode. The half-wave plate 210 rotates the first polarization mode to the second polarization mode by introducing a phase shift of 180 degrees (or 7i radians) between two perpendicular polarization components of the first light beam FB. The half-wave plate 210 may be made of birefringent crystals such as quartz, calcite, mica, or the like.

[0050] The beam deflector 212 may be optically coupled to the half- wave plate 210 and configured to receive the first light beam FB with the second polarization mode from the half-wave plate 210. The beam deflector 212 may be further configured to deflect the first light beam FB with the second polarization mode to the polarization beam combiner 216. The first light beam FB is deflected to the polarization beam combiner 216 at a right angle. In other words, the beam deflector 212 may deflect the first light beam FB by 90 degrees. The deflection of the first light beam FB is achieved through the principle of total internal reflection in the beam deflector 212 to ensure precise alignment with minimal energy loss. Examples of the beam deflector 212 may include a turningprism, a turning mirror, or the like. Further, the beam deflector 212 may be manufactured from optical grade materials such as BK7 glass or fused silica, known for high transparency and low scattering properties.

[0051] The clear glass 214 may be optically coupled to the array of micro-lenses 208. Particularly, the clear glass 214 may be optically coupled to the second micro-lens 208b and configured to receive the second light beam SB collimated by the second micro-lens 208b. The clear glass 214 may be further configured to guide the second light beam SB from the second micro-lens 208b to the polarization beam combiner 216.

[0052] The polarization beam combiner 216 may be optically coupled to the beam deflector 212 and the clear glass 214. The polarization beam combiner 216 may be configured to receive the first light beam FB and the second light beam SB. Further, the polarization beam combiner 216 may be configured to combine the first light beam FB and the second light beam SB into the third light beam TB. The polarization beam combiner 216 may be further configured to output the third light beam TB. As the first light beam FB has the second polarization mode and the second light beam SB has the first polarization mode, the third light beam TB has a low degree of polarization. In an example, the degree of polarization of the third light beam TB is less than 0.1. Additionally, in an example, the third light beam TB has a polarization extinction ratio of less than 0.9 decibels.

[0053] As the first SLED 202 and the second SLED 204 can be designed to emit light beyond C- band spectrum, L-band spectrum, and O-band spectrum, the ASE light source 100 can be realized to emit the third light beam TB beyond the C-band spectrum, the L-band, and the O-band. Thus, the ASE light source 100 is operable in a wide spectrum in comparison to conventional erbium- doped ASE light source which cannot operate beyond the C-band spectrum.

[0054] The ASE light source 100 may further include a thermoelectric cooler (TEC) 218 coupled to the SLED chip 102. The TEC 218 may be configured to cool the SLED chip 102. The submount 206 along with the SLED chip 102 may be assembled on the TEC 218. The TEC 218 may regulate the temperature of the SLED chip 102 and the submount 206. Thermal stability is achieved in the ASE light source 100 based on the TEC 218 as the TEC 218 maintains the thermal stability of the SLED chip 102 under varying environmental conditions. The TEC 218 may operate using the Peltier effect, which transfers heat away from the SLED chip 102 to a heat sink (not shown). As the temperature of the SLED chip 102 is stabilized, thermal drift that could otherwise affect the wavelength, power, and polarization characteristics of the third light beam TB is prevented. In some embodiments, the TEC 218 may be integrated with a feedback control system that facilitates precise temperature adjustments based on real-time monitoring of the temperature of the SLED chip 102.

[0055] In numerous embodiments, the ASE light source 100 may be assembled in a 14-pin butterfly package. The ASE light source 100 may be utilized in applications such as optical tomography, fiber-optic gyroscope, spectrum detection, and the like.

[0056] In numerous additional embodiments, a pigtailed fiber optic may be coupled to the ASE light source 100 to receive the third light beam TB. In an example, the third light beam TB may be directed into a single-mode fiber for use in an optical coherence tomography system or a multimode fiber for telecommunication testing. In further additional embodiments, third light beam TB may be outputted by way of free-space emission.

[0057] In a variety of embodiments, the polarization of the third light beam TB may be actively controlled by varying respective drive currents of the first SLED 202 and the second SLED 204, thereby directly adjusting TM mode and TE mode optical powers to be combined to form a final optical power of the third light beam TB. In other words, the ASE light source 100 facilitates active polarization control of the third light beam TB.

[0058] In many embodiments, modulation of each of the TE mode and TM mode components of the third light beam TB may be realized by independent current drive of the first SLED 202 and the second SLED 204. Independent modulation control of each eigen TE and TM polarization modes enables encoding of separate signals in each polarization modes.

[0059] FIG. 3 illustrates a top view 300 of the ASE light source 100 in accordance with an embodiment of the present disclosure. The top view 300 illustrates the first SLED 202 and the second SLED 204 assembled on the submount 206 such that the first light beam FB and the second light beam SB are orthogonal to the submount 206. Additionally, the top view 300 illustrates the diverging nature of the first and second light beams FB and SB emitted from the first SLED 202 and the second SLED 204, respectively. Further, the first micro-lens 208a collimates the first light beam FB to the half-wave plate 210 and the second micro- lens 208b collimates the second light beam SB to the clear glass 214.

[0060] The half-wave plate 210 may include an anti-reflection coating 302 deposited on a backside of the half-wave plate 210 to prevent reflection of the collimated first light beam FB with the second polarization mode. Further, a high reflection coating 304 may be deposited between the half-wave plate 210 and the clear glass 214 to prevent crosstalk between the first light beam FB and the second light beam SB. Further, the beam deflector 212 may include a highly reflective surface 306 to deflect the first light beam FB to the polarization beam combiner 216.

[0061] In some embodiments, the half-wave plate 210 is coupled to the clear glass 214, and the beam deflector 212 is coupled to the polarization beam combiner 216 to achieve mechanical stability and robustness in the ASE light source 100.

[0062] The first SLED 202 and second SLED 204 are assembled on the submount 206 with a predetermined separation between the first SLED 202 and second SLED 204 to match a period of the array of micro-lenses 208 for facilitating collimation of the first and second light beams FB and SB. The period of the array of micro-lenses 208 refers to a distance between the centers of two adjacent micro-lenses (e.g., the first micro-lens 208a and the second micro-lens 208b) in the array of microlenses 208. In an example, the period of the array of micro-lenses 208 is 0.250 millimeters.

[0063] In numerous embodiments, an anti-reflection coating is deposited on, output facets of the first and second SLEDs 202 and 204, an outer surface of the beam deflector 212, an outer surface of the polarization beam combiner 216, front and back surfaces of the array of micro-lenses 208, and front and back surfaces of the half-wave plate 210, to prevent loss of light due to reflection and enhance transmission efficiency of the ASE light source 100.

[0064] FIG. 4 illustrates a schematic block diagram of an ASE light circuit 400 in accordance with an embodiment of the present disclosure. The ASE light circuit 400 may include a plurality of ASE light sources 402 and a set of mirrors 404. The plurality of ASE light sources 402 may include a first ASE light source 402a, a second ASE light source 402b, a third ASE light source 402c, a fourth ASE light source 402d, . . . , and an nth ASE light source 402n. Each ASE light source of the plurality of ASE light sources 402 may be structurally and functionally similar to the ASE light source 100. Thus, each ASE light source of the plurality of ASE light sources 402 comprises an SLED chip and a beam modification assembly that is optically coupled to the SLED chip.

[0065] The SLED chip may be configured to emit a fourth light beam and a fifth light beam. The fourth and fifth light beams are emitted in the first polarization mode. The beam modification assembly may be configured to receive the fourth light beam and the fifth light beam and rotate the first polarization mode of the fourth light beam to the second polarization mode. The beam modification assembly may be further configured to combine the fourth light beam having the second polarization mode with the fifth light beam having the first polarization mode into a sixth light beam and output the sixth light beam. The set of mirrors 404 may be optically coupled to the plurality of ASE light sources 402 and configured to receive the sixth light beam from each ASE light source of the plurality of ASE light sources 402. The set of mirrors 404 may be further configured to combine the sixth light beam from each ASE light source of the plurality of ASE light sources 402 to a combined light beam and output the combined light beam. The combined light beam is a non-polarized light beam with a low degree of polarization and high power.

[0066] FIG. 5 represents a flowchart 500 (e.g., a method 500) that illustrates a method of amplified spontaneous emission in the ASE light source 100 in accordance with an embodiment of the present disclosure. At 502, the method 500 includes emitting the first light beam FB and the second light beam SB by the SLED chip 102 of the ASE light source 100. The first light beam FB and the second light beam SB are emitted in the first polarization mode.

[0067] At 504, the method 500 further includes receiving, by the beam modification assembly 104, the first light beam FB and the second light beam SB from the SLED chip 102. At 506, the method 500 includes rotating, by the beam modification assembly 104, the first polarization mode of the first light beam FB to the second polarization mode.

[0068] At 508, the method 500 further includes combining, by the beam modification assembly 104, the first light beam FB having the second polarization mode with the second light beam SB having the first polarization mode into the third light beam TB. At 510, the method 500 further includes outputting, by the beam modification assembly 104, the third light beam TB. The third light beam TB is non-polarized and has a low degree of polarization.

[0069] The present invention provides an ASE light source 100 that emits the third light beam TB which has a low degree of polarization and high optical power compared to light beams emitted by conventional ASE light sources. Additionally, the ASE light source 100 can emit an ASE light beam in a wide spectrum compared to conventional erbium-doped ASE light sources as the ASE light source 100 is realized by the first SLED 202 and the second SLED 204 that operate in a wide spectrum. Furthermore, the ASE light source 100 is compact and has a smaller form factor compared to conventional erbium-doped ASE light sources.

[0070] The ASE light source 100 may be applicable in various fields requiring stable, precise, and tailored ASE light sources. In telecommunications, the low degree of polarization optical output outputted by the ASE light source ensures reduced polarization-dependent losses, making it suitable for fiber optic communication networks and wavelength division multiplexing. In optical sensing, the ASE light source 100 may be utilized in fiber optic gyroscopes, interferometric systems, and strain sensors, where polarization-stable and thermally consistent light sources are critical. The ASE light source 100 is also highly suitable for biomedical imaging, including optical coherence tomography, where broadband low-coherence light sources are essential for achieving high- resolution imaging. Additionally, the compact design of the ASE light source 100 allows customization for use in industrial meteorology, laser calibration systems, and signal processing applications, where precise beam shaping and polarization control are required.

[0071] In the claims, the words ‘comprising’, ‘including’, and ‘having’ do not exclude the presence of other elements or steps than those listed in a claim. The terms “a” or “an,” as used herein, are defined as one or more than one. Unless stated otherwise, terms such as “first” and “second” are used to arbitrarily distinguish between the elements such terms describe. Thus, these terms are not necessarily intended to indicate temporal or other prioritization of such elements. The fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to advantage.

[0072] While various exemplary embodiments of the disclosed system and method have been described above it should be understood that they have been presented for purposes of example only, not limitations. It is not exhaustive and does not limit the disclosure to the precise form disclosed. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the present disclosure, as described.

Claims

CLAIMSWhat is claimed is:

1. An amplified spontaneous emission (ASE) light source, comprising: a superluminescent light emitting diode (SLED) chip configured to: emit a first light beam and a second light beam, wherein the first and second light beams are emitted in a first polarization mode; and a beam modification assembly that is optically coupled to the SLED chip and configured to: receive the first light beam and the second light beam; rotate the first polarization mode of the first light beam to a second polarization mode; combine the first light beam having the second polarization mode with the second light beam having the first polarization mode into a third light beam; and output the third light beam.

2. The ASE light source of claim 1, wherein the SLED chip comprises: a first SLED configured to emit the first light beam; and a second SLED configured to emit the second light beam.

3. The ASE light source of claim 2, further comprising a submount coupled to the SLED chip, wherein the first SLED is assembled on the submount such that the emitted first light beam is orthogonal to the submount, and wherein the second SLED is assembled on the submount such that the emitted second light beam is orthogonal to the submount.

4. The ASE light source of claim 3, wherein the submount is a heat dissipating submount.

5. The ASE light source of claim 1, further comprising a thermoelectric cooler coupled to the SLED chip and configured to cool the SLED chip.

6. The ASE light source of claim 1, wherein the beam modification assembly comprises an array of micro-lenses configured to: receive the first light beam and the second light beam; and collimate the first light beam and the second light beam in a horizontal direction.

7. The ASE light source of claim 6, wherein the beam modification assembly further comprisesa half-wave plate optically coupled to the array of micro-lenses and configured to rotate the first polarization mode of the first light beam to the second polarization mode, and wherein the first light beam is collimated into the half-wave plate from the array of micro-lenses.

8. The ASE light source of claim 7, wherein the beam modification assembly further comprises a beam deflector optically coupled to the half-wave plate, and a polarization beam combiner optically coupled to the beam deflector and the array of micro-lenses, wherein the beam deflector is configured to deflect the first light beam with the second polarization mode to the polarization beam combiner, and wherein the polarization beam combiner is configured to: receive the first light beam and the second light beam; combine the first light beam and the second light beam into the third light beam; and output the third light beam.

9. The ASE light source of claim 8, wherein the first light beam is deflected to the polarization beam combiner at a right angle.

10. The ASE light source of claim 8, wherein the beam modification assembly further comprises a clear glass optically coupled to the array of micro-lenses and the polarization beam combiner, and wherein the clear glass is configured to guide the second light beam from the array of micro-lenses to the polarization beam combiner.

11. The ASE light source of claim 10, wherein a high-reflection coating is deposited between the half-wave plate and the clear glass to prevent cross-talk between the first light beam and the second light beam.

12. The ASE light source of claim 10, wherein the array of micro-lenses comprises: a first micro-lens configured to collimate the first light beam to the half- wave plate; and a second micro-lens configured to collimate the second light beam to the clear glass.

13. The ASE light source of claim 1, wherein the third light beam is a non-polarized light beam.

14. The ASE light source of claim 1, wherein a degree of polarization of the third light beam is low in comparison to degree of polarizations of the first and second light beams.

15. The ASE light source of claim 14, wherein the degree of polarization of the third light beam is less than 0.1.

16. The ASE light source of claim 1, wherein the third light beam has a polarization extinction ratio of less than 0.9 decibels.

17. The ASE light source of claim 1, wherein the first polarization mode corresponds to transverse electric mode and the second polarization mode corresponds to transverse magnetic mode.

18. An amplified spontaneous emission (ASE) light circuit, comprising: a plurality of ASE light sources, wherein each ASE light source of the plurality of ASE light sources comprises: a superluminescent light emitting diode (SLED) chip configured to: emit a first light beam and a second light beam, wherein the first and second light beams are emitted in a first polarization mode; and a beam modification assembly that is optically coupled to the SLED chip and configured to: receive the first light beam and the second light beam; rotate the first polarization mode of the first light beam to a second polarization mode; combine the first light beam having the second polarization mode with the second light beam having the first polarization mode into a third light beam; and output the third light beam; and a set of mirrors optically coupled to the plurality of ASE light sources and configured to: receive the third light beam from each ASE light source of the plurality of ASE light sources; combine the third light beam from each ASE light source of the plurality of ASE light sources to a fourth light beam; and output the fourth light beam.

19. The ASE light source of claim 18, wherein the fourth light beam is a non-polarized light beam.

20. A method of amplified spontaneous emission (ASE) in an ASE light source, the method comprising: emitting a first light beam and a second light beam, by a superluminescent light emitting diode (SLED) chip of the ASE light source, wherein the first and second light beams are emitted in a first polarization mode;receiving, by a beam modification assembly of the ASE light source, the first light beam and the second light beam; rotating, by the beam modification assembly, the first polarization mode of the first light beam to a second polarization mode; combining, by the beam modification assembly, the first light beam having the second polarization mode with the second light beam having the first polarization mode into a third light beam; and outputting, by the beam modification assembly, the third light beam.

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