A two-kappa DBR laser includes an active section, a HR mirror, a first DBR section, and a second DBR section. The HR mirror is coupled to a rear of the active section. The first DBR section is coupled to a front of the active section, the first DBR section having a first DBR grating with a first kappa κ1. The second DBR section is coupled to a front of the first DBR section such that the first DBR section is positioned between the active section and the second DBR section. The second DBR section has a second DBR grating with a second kappa κ2 less than the first kappa κ1. The two-kappa DBR laser is configured to operate in a lasing mode and has a DBR reflection profile that includes a DBR reflection peak. The lasing mode is aligned to a long wavelength edge of the DBR reflection peak.

Methods for wavelength determination of widely tunable lasers and systems thereof may be implemented with solid-state laser based photonic systems based on photonic integrated circuit technology as well as discrete table top systems such as widely-tunable external cavity lasers and systems. The methods allow integrated wavelength control enabling immediate system wavelength calibration without the need for external wavelength monitoring instruments. Wavelength determination is achieved using a monolithic solid-state based optical cavity with a well-defined transmission or reflection function acting as a wavelength etalon. The solid-state etalon may be used with a wavelength shift tracking component, e.g., a non-balanced interferometer, to calibrate the entire laser emission tuning curve within one wavelength sweep. The method is particularly useful for integrated photonic systems based on Vernier-filter mechanism where the starting wavelength is not known a-priori, or for compact widely tunable external cavity lasers eliminating the need for calibration of wavelength via external instruments.

Methods for wavelength determination of widely tunable lasers and systems thereof may be implemented with solid-state laser based photonic systems based on photonic integrated circuit technology as well as discrete table top systems such as widely-tunable external cavity lasers and systems. The methods allow integrated wavelength control enabling immediate system wavelength calibration without the need for external wavelength monitoring instruments. Wavelength determination is achieved using a monolithic solid-state based optical cavity with a well-defined transmission or reflection function acting as a wavelength etalon. The solid-state etalon may be used with a wavelength shift tracking component, e.g., a non-balanced interferometer, to calibrate the entire laser emission tuning curve within one wavelength sweep. The method is particularly useful for integrated photonic systems based on Vernier-filter mechanism where the starting wavelength is not known a-priori, or for compact widely tunable external cavity lasers eliminating the need for calibration of wavelength via external instruments.

A semiconductor optical amplifier integrated laser includes a semiconductor laser oscillator portion that oscillates laser light having a wavelength included in a gain band and a semiconductor optical amplifier portion that amplifies laser light output from the semiconductor laser oscillator portion. The semiconductor laser oscillator portion and the semiconductor optical amplifier portion have one common p-i-n structure, the common p-i-n structure includes an active layer, a cladding layer provided apart from the active layer, and a common functional layer formed in the cladding layer, and the common functional layer includes a first portion that reflects light having a wavelength within the gain band in the semiconductor laser oscillator portion and a second portion that transmits light having a wavelength within the gain band in the semiconductor optical amplifier portion.

A distributed feedback plus reflection (DFB+R) laser includes an active section, a passive section, a low reflection (LR) mirror, and an etalon. The active section includes a distributed feedback (DFB) grating and is configured to operate in a lasing mode. The passive section is coupled end to end with the active section. The LR mirror is formed on or in the passive section. The etalon includes a portion of the DFB grating, the passive section, and the LR mirror. The lasing mode of the active section is aligned to a long wavelength edge of a reflection peak of the etalon.

A two-kappa DBR laser includes an active section, a HR mirror, a first DBR section, and a second DBR section. The HR mirror is coupled to a rear of the active section. The first DBR section is coupled to a front of the active section, the first DBR section having a first DBR grating with a first kappa κ1. The second DBR section is coupled to a front of the first DBR section such that the first DBR section is positioned between the active section and the second DBR section. The second DBR section has a second DBR grating with a second kappa κ2 less than the first kappa κ1. The two-kappa DBR laser is configured to operate in a lasing mode and has a DBR reflection profile that includes a DBR reflection peak. The lasing mode is aligned to a long wavelength edge of the DBR reflection peak.

An isolator-free laser includes an etalon, an active section, and a low reflection (LR) mirror. The etalon includes a passive section of the isolator-free laser and a reflection profile. The active section is coupled end to end with the passive section. The active section has a distributed feedback (DFB) grating and a lasing mode at a long wavelength side of a reflection peak of the reflection profile. The LR mirror is formed on a front facet of the passive section. The long wavelength edge of the reflection peak of the reflection profile may have a slope greater than 0.006 GHz.sup.1. A RIN of the isolator-free laser under 20 decibels (dB) external cavity optical feedback may be less than or equal to 130 dBc/Hz.

A distributed reflector (DR) laser may include a distributed feedback (DFB) region and a distributed Bragg reflector (DBR). The DFB region may have a length in a range from 30 micrometers (m) to 100 m and may include a DFB grating with a first kappa in a range from 100 cm.sup.1 to 150 cm.sup.1. The DBR region may be coupled end to end with the DFB region and may have a length in a range from 30-300 m. The DBR region may include a DBR grating with a second kappa in a range from 150 cm.sup.1 to 200 cm.sup.1. The DR laser may additionally include a lasing mode and a p-p resonance frequency. The lasing mode may be at a long wavelength side of a peak of a DBR reflection profile of the DBR region. The p-p resonance frequency may be less than or equal to 70 GHz.

A semiconductor light-emitting device includes an active layer including quantum dots, a diffraction grating, a low-reflectance film disposed at a light-emitting end of the active layer, and a high-reflectance film disposed at another end of the active layer and having an optical reflectance higher than an optical reflectance of the low-reflectance film.

Methods for wavelength determination of widely tunable lasers and systems thereof may be implemented with solid-state laser based photonic systems based on photonic integrated circuit technology as well as discrete table top systems such as widely-tunable external cavity lasers and systems. The methods allow integrated wavelength control enabling immediate system wavelength calibration without the need for external wavelength monitoring instruments. Wavelength determination is achieved using a monolithic solid-state based optical cavity with a well-defined transmission or reflection function acting as a wavelength etalon. The solid-state etalon may be used with a wavelength shift tracking component, e.g., a non-balanced interferometer, to calibrate the entire laser emission tuning curve within one wavelength sweep. The method is particularly useful for integrated photonic systems based on Vernier-filter mechanism where the starting wavelength is not known a-priori, or for compact widely tunable external cavity lasers eliminating the need for calibration of wavelength via external instruments.